Effect of Debinding Method and Sintering Atmosphere on Fused Filament Fabrication Printed 17-4PH Stainless Steel at Intermediate Sintering Temperatures

Effect of Debinding Method and Sintering Atmosphere on Fused Filament Fabrication Printed 17-4PH Stainless Steel at Intermediate Sintering Temperatures | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effect of Debinding Method and Sintering Atmosphere on Fused Filament Fabrication Printed 17-4PH Stainless Steel at Intermediate Sintering Temperatures Nur Farrahain Nadia Ahmad This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7828599/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Fused filament fabrication (FFF) of 17-4PH stainless steel provides a cost-effective route for producing complex components, but the final properties strongly depend on debinding and sintering. Unsuitable conditions may cause incomplete binder removal, oxidation, and poor densification; thus, optimized debinding strategies and atmosphere selection are essential to balance strength, stiffness, and toughness. Existing studies on FFF 17-4PH limited, particularly regarding the comparative influence of debinding method, and sintering atmosphere. This study aimed to study solvent–thermal debinding combined with sintering at ~ 1100°C under argon and vacuum atmospheres. Characterization included dimensional and mass changes, microstructural evolution, and mechanical testing. Vacuum-sintered specimens exhibited 7–13% linear shrinkage, 74.4% relative density, and 25.6% porosity, achieving superior tensile performance: 112 GPa Young’s modulus, 40.6 MPa yield strength, 167 MPa ultimate strength, and 0.629 strain at break. By contrast, argon-sintered specimens showed only ~ 1% shrinkage, reduced density (55.7%), and higher porosity (44.3%), resulting in tensile properties nearly 25-fold lower. Load-bearing model predictions agreed with experiments with a correction factor of 1.426. Despite higher strength, vacuum-sintered specimens suffered toughness limitations due to voids and carbon-induced embrittlement, causing brittle fracture under impact. Conversely, argon-sintered specimens, though weaker, displayed more uniform porosity and reduced internal stresses, enabling better energy absorption during Charpy testing. These findings highlight a trade-off: thermal debinding alone is unsuitable for this filament, while combining solvent with controlled thermal profiling is recommended. Vacuum sintering improves strength and stiffness, whereas argon sintering enhances impact tolerance, emphasizing the importance of atmosphere selection. fused filament fabrication 17 − 4 PH stainless steel debinding sintering mechanical propertie Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1 Introduction Metal Injection Molding (MIM) is commonly used as an alternative to conventional manufacturing methods such as casting, welding, and even machining, particularly for producing metal complex-shaped components. However, from a manufacturing perspective, MIM can be both time-consuming and expensive, especially for small production runs (Bankapalli et al., 2023 ). One of major limitations in MIM is the need for a dedicated mold for each part design. Designing and manufacturing a new mold can take weeks or even months, and any design changes require a completely new mold, further extending lead times and escalating costs (increase cost per unit). These delays can disrupt production schedules and increase overall manufacturing expenses, particularly when tight deadlines must be met. To address these limitations, Metal Additive Manufacturing (MAM) has emerged as a promising solution, offering superior design flexibility, shorter lead times, and potential cost advantages for low- to medium-volume production (Armstrong et al., 2022 ). There are several options of metal AM (ISO/ASTM 52900) like powder bed fusion (PBF), binder jetting (BJ), directed energy deposition (DED) and material extrusion (ME) technologies (Cao et al., 2023 ; Tebianian et al., 2023 ). PBF selectively melts or sinters thin powder layers using a high-energy source, enabling near-full density, high-resolution parts with excellent mechanical properties (Gong et al., 2021 ; Madhavadas et al., 2022 ). BJ deposits a liquid binder onto a powder bed layer by layer, with the green parts subsequently strengthened through post-processing, making it suitable for large, low-cost, and functionally integrated components (Lores Erazo et al., 2019 ; Zhu et al., 2025 ). DED feeds metal powder or wire directly into a melt pool generated by a laser, electron beam, or plasma arc, allowing large build volumes than PBF and efficient component repair (Özel et al., 2023 ; Svetlizky et al., 2021 ). In ME, semi-liquid, semi-solid, or solid form feedstock are extruded through a nozzle and deposited onto a substrate in a controlled manner (Suwanpreecha & Manonukul, 2022b ). While AM technologies offer geometric freedom in producing metallic parts, they face key drawbacks, including high capital cost and operational cost (due to expensive raw powders, metal powder quality control via gas or plasma atomization techniques (Sæterbø & Solvang, 2023 ) and energy demand) (Strong et al., 2018 ), strict safety requirements, and microstructural variations from rapid thermal cycling that affect final mechanical properties (Kok et al., 2018 ) include residual stresses, thermal cracks, and anisotropy (LeBrun et al., 2015 ). To address these challenges, researchers and industry are developing additive manufacturing processes that produce metallic components more affordably and sustainably. Fused Filament Fabrication (FFF) is categorized under material extrusion-based techniques, a developed technology that use the existing plastic FFF technology to metal. In metal FFF, a metal powder (mixed with a thermoplastic binder) filament is extruded to form a green part, can then be transformed into a dense metal part using debinding and sintering cycles. Debinding to remove the binder, and finally, high temperature sintering to densify the metal (Jacob et al., 2024 ; Singh et al., 2021 ). This procedure provides one of the more accessible and secure beginnings into metal AM, as the powder particle is encapsulated in a polymer, creating a lower risk of powder handling (Costa et al., 2023 ). Metal FFF is increasingly recognized as a convenient and cost-effective approach for prototyping and low-volume metal part production, though with the trade-offs of requiring a secondary sintering step and experiencing considerable shrinkage during densification (Léonard & Tammas-Williams, 2022 ). 17-4PH is a precipitation-hardened martensitic stainless steel is well-known due to its outstanding strength and resistance to corrosion (García-Hernández et al., 2024 ; Zhang & Roch, 2022 ), driving its widespread use in sectors such as marine, petrochemical, nuclear, and aerospace (Suwanpreecha & Manonukul, 2022a ). Conventional manufacturing and post-processing of 17 − 4 PH stainless steel can achieve properties suitable for industrial applications; however, due to its high hardness, 17-4PH steel exhibits poor machinability, making it challenging to shape into complex structures (Joo et al., 2018 ; Sivaiah & Chakradhar, 2017 ) and exhibit significant variance in microstructure (Lai et al., 2020 ). Research on FFF of 17 − 4 PH stainless steel is still limited. Tosto et al. ( 2021 ) highlighted the lack of studies on FFF-printed 17 − 4 PH,and Jones et al. ( 2023 ) reviewed the mechanical properties of 17 − 4 PH parts produced by additive manufacturing, focusing on Markforged’s MetalX™; however, they did not address debinding methods or sintering atmospheres. Moreover, Markforged and other commercial platforms do not disclose binder compositions or detailed processing parameters, leaving a knowledge gap in optimizing post-processing for functional performance.The quality of FFF metal parts depends on feedstock characteristics (such as metal loading, polymer type, and additives) and processing conditions (Jacob et al., 2024 ). However, the effects of debinding methods and sintering atmospheres on densification, microstructure, and mechanical properties of 17 − 4 PH FFF parts are not well understood, representing a key research gap. Therefore, this study focuses on FFF-printed 17 − 4 PH stainless steel, specifically investigating debinding methods (solvent and thermal) and sintering atmospheres using vacuum and argon. The effects of these processes on characteristics, including dimensional and mass changes, microstructural evolution, and mechanical properties, are systematically analyzed. 2 Material and Method 2.1 Sample preparation FFF printing was performed using a commercially available 17 − 4 PH stainless steel filament, consisting of approximately ~ 60 vol% powder metal (≈ 80 wt%, detail composition Table 1 ) with powder particle sizes of 10–45 µm embedded in a polymer binder system. 17 − 4 PH were printed and sintered in outsourcing using a Metal X printer with a 0.4 mm hard steel nozzle to withstand filament abrasiveness, using a 0.2 mm layer height to balance resolution and build time, followed the printing settings specified by Markforged. Key printing parameters are summarized in Table 2 . Table 1 Chemical composition of the 17 − 4 PH stainless steel sample under study Element Cr Ni Cu Si Mn Nb C P S Fe Composition (%) 15 − 17.5 3 − 5 3 − 5 1 (max) 1 (max) 0.15–0.45 0.07 0.04 (max) 0.03 (max) Bal. Note: Chromium (Cr); Nickel (Ni); Copper (Cu); Silicon (Si); Manganese (Mn); Niobium (Nb); Carbon (C); Phosphorous (P); Sulfur (S); Iron (Fe) Table 2 Parameter for 17 − 4 PH stainless steel FFF printing process (Markforged) Parameter Value Rationale Extruder temperature 250°C Optimal flow without binder degradation 220°C (Kedziora et al., 2022 ) Print bed temperature 100°C Promotes adhesion and minimizes warping 115°C (Kedziora et al., 2022 ) Printing speed 30 mm/s (perimeters), 40 mm/s (infill) Ensures proper filament deposition Infill 100% (solid) Ensures any porosity is from the process, not design Infill pattern Rectilinear (0°/90° alternating) Creates fully solid parts Perimeters 2–3 outlines Ensures clean shape Cooling Minimal or off Prevents thermal gradients Filament preparation Dried at ~ 50°C for 4 hours Removes moisture to prevent defects Tensile specimens were printed in the ASTM D638 Type V dogbone geometry (n = 6 per condition), while impact specimens were sub-sized according to ASTM E23 for Charpy testing (n = 6 per condition) (Fig. 1 ). All samples were produced in the same batch under consistent print runs with identical parameters to ensure uniformity. After printing, the green parts were allowed to cool to room temperature on the build plate before being carefully removed. 2.2 Debinding process Debinding is carried out to eliminate the binder while preserving the geometry of the green part, and complete removal is required since residual carbon can hinder sintering and deteriorate the final quality. Two debinding method used as variables: solvent debinding and thermal debinding. Solvent debinding was carried out by immersing the green parts in a hexane bath at 60°C for 4 h inside a closed glass vessel, with gentle magnetic stirring to ensure uniform exposure. The debinding duration was determined by part thickness, as reported by (Zhang & Roch, 2022 ). A targeted mass loss of 3.5–4 wt% was set as the criterion for effective extraction. After treatment, the specimens (brown parts) exhibited extensive extraction of the soluble binder fraction, while retaining the backbone polymer and metallic powder, resulting in a leaner texture and duller surface finish. After solvent debinding of 17 − 4 PH stainless steel specimens, the resulting brown parts were air-dried to remove residual hexane, followed by oven drying at 50°C for 2 hours. This step was necessary to minimize internal gas evolution during subsequent heating, thereby reducing the risk of deformation or cracking. The ratio of weight loss in each step to the total weight was used to evaluate the binder removal rate and efficiency throughout the debinding process. Thermal debinding was carried out in a tube furnace under either argon or vacuum atmosphere to remove the remaining backbone polymer from the binder system. A controlled heating profile was applied, with a ramp rate of 5°C/min from 20°C to 550°C for 96 min, followed by a 45 min dwell (holding time) at the peak temperature. A slower heating rate within the critical temperature range enhances binder removal from the brown parts because it allows sufficient time for the polymer binder to gradually decompose and diffuse out, thereby reducing internal gas pressure. This controlled decomposition minimizes stress concentration, which in turn reducing surface cracking. Additionally, uncontrolled and rapid decomposition of the binder may occur if volatile by-products accumulate within the part, incurring the risk of sudden combustion from trapped gases. This phenomenon not only causes localized overheating but also generates internal pressure, which can damage the part. By promoting gradual gas release, the debinding process prevents abrupt binder degradation and preserves the structural stability of the brown part prior to sintering (Raza et al., 2023 ; Supriadi et al., 2017 ). 2.3 Sintering Process After debinding, the brown parts were sintered two different furnace systems: an OTF-1200X tube furnace for high-vacuum sintering (< 5 × 10⁻⁵ bar) and a Nabertherm LT 9/11/HA furnace for sintering under an argon atmosphere (constant flow ~ 0.15L/min). The sintering cycle was designed to enhance solid-state diffusion bonding of the 17 − 4 PH stainless steel particles, besides preventing grain coarsening and unwanted surface reaction. Conventional sintering of 17-4PH stainless steel at 1300–1350°C entails high energy consumption and environmental impact, prompting interest in intermediate-temperature sintering (~ 1100°C) to balance densification, dimensional accuracy, and mechanical and corrosion performance with reduced processing costs. All process parameters were standardized to ensure reproducibility, with atmosphere processing condition being the only variable (Table 3 ). Table 3 Sintering constant parameters for FFF-printed 17 − 4 PH stainless steel Parameter Value Rationale Heating rate 10°C/min (from 550°C to 1100°C) Ensures efficient transition into sintering zone while avoiding overshoot Sintering hold time 180 minutes (3 hours) Allows for sufficient particle bonding and densification Cooling rate Furnace cooling under same atmosphere (no heating) Prevents thermal shock and controls shrinkage or distortion Sample placement Alumina setters with alumina powder spacing Prevents sticking and distortion Initial atmosphere Argon flush up to 550°C Carries away binder vapors safely The heating rate was set at 10°C/min, start from 550°C (Zhang & Roch, 2022 ) to the peak sintering temperature (1100°C). An isothermal holding time was 3 h at 1100°C facilitated particle diffusion and densification. After sintering completed, the specimens were cooled to room temperature within the same furnace and atmosphere (vacuum or argon) to minimize thermal gradients and prevent distortion or microcracking. To preserve part integrity during sintering, the specimens were placed on alumina ceramic setters, with a separating layer of alumina powder to prevent adhesion to the baseplate. 2.4 Method of analysis 2.4.1 Material Characterization Dimensional and mass changes were evaluated across three processing stages—the as-printed FFF green parts, the brown parts obtained after solvent and thermal debinding, and the final sintered components—and subsequently compared and analyzed. This evaluation provides insight into the extent of densification, dimensional stability, material flow, and mass loss during each stage, enabling detection of potential defects such as warping or distortion. Furthermore, monitoring these changes helps correlate processing behavior with the final mechanical performance and structural integrity of the sintered components. In order to analyze the internal microstructure of the sintered samples and their composition, microstructural characterization was carried out using optical microscopy (OLYMPUS BX53 M) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) (Hitachi SU8020). Sintered specimens from the vacuum and argon specimen were sectioned to obtain cross-sections using a low-speed diamond saw, mounted in conductive phenolic resin, and polished sequentially with silicon carbide papers (P240–P1200) followed by diamond suspensions. SEM imaging was at maximum backscattered electron (BSE) mode between 15 kV and about 15 mm working distance, which gave the pore morphology a good depth of field. Porosity percentage was determined as the average of three measurements taken from three distinct areas of each sample, by calculating the area fraction of pores, with an estimated error margin of 1–2%. Porosity measurements were conducted based on SEM image analysis using threshold-based binarization techniques in ImageJ. The porosity (P) was calculated as the percentage of black (void) pixels to total pixel area, representing pore volume fraction. 2.4.2 Mechanical characterization Sintered specimens were fabricated according to ASTM D638 Type V geometry and subjected to uniaxial tensile testing. All tests were conducted using a Shimadzu EZ-X universal testing machine equipped with a 5 kN load cell, at a constant crosshead speed of 5 mm/min, corresponding to an approximate strain rate of 0.002 s⁻¹. Testing was performed at ambient laboratory conditions (~ 25°C) following the relevant ASTM standards. Fracture toughness was evaluated via Charpy V-notch impact tests in accordance with ASTM E23. Prior to testing, each sintered bar was machined to introduce a standard V-notch. Tests were performed using a pendulum-type Charpy impact tester with a 50 J hammer at room temperature. 3 Result and Discussion 3.1 Debinding Behavior of 17-4PH Stainless Steel Green Parts Since the as-printed green parts contain approximately 20 vol% polymer binder, debinding process is essential for binder removal in order to allow effective sintering and metallurgical bonding between metal particles while preserving structural integrity (Tafti et al., 2021 ). Two debinding method involving solvent debinding and thermal debinding were evaluated. To ensure comparability, the constant parameters across all experiments included the green part geometry and the binder system composition. A preliminary weight-loss experiment was conducted to validate solvent debinding performance. A green specimen was halved, with one half immersed in room-temperature (RT) hexane and the other in hexane at 60°C. Samples were removed hourly for four hours, dried, and weighed. After four hours of immersion, hexane at 60°C produced a weight loss exceeding 6%, surpassing the target threshold, whereas room-temperature hexane achieved only 4.5% weight loss for binder removal, indicating significantly lower efficiency. Although solvent debinding at 60°C efficiently removes the soluble binder fraction mainly at the surface, its penetration into the interior of the compact is limited by diffusion. As a result, binder extraction occurs more rapidly at the surface while significant amounts of the backbone binder remain trapped inside the part. Solvent treatment alone cannot achieve homogeneous debinding throughout the specimen, which must be decomposed through subsequent controlled thermal debinding to decompose the remaining binder uniformly, prevent internal defects such as blistering, cracking, or warping during sintering and preserve part integrity (Lotfizarei et al., 2023 ). Ni et al. ( 2018 ) similarly reported that solvent-assisted debinding produces an interconnected pore structure that facilitates gas escape and enables efficient thermal removal of residual binder. Based on these findings, a 24-hour immersed in 60°C hexane was adopted as the solvent debinding condition for subsequent thermal debinding for the actual specimen size. In contrast, direct thermal debinding led to catastrophic failure, as shown in Fig. 2 . The specimens exhibited severe over-burning, extensive oxidation, gas-induced internal cracking, and surface blistering. These results underscore the necessity of a solvent-assisted step to enable gradual binder removal and to prevent internal pressure buildup that compromises structural integrity. Thermal debinding alone was therefore unsuitable for 17-4PH stainless steel green parts, primarily due to their high polymer content (~ 20 vol%). During direct thermal debinding, the ~ 20 vol% polymer binder present in the green parts decomposes rapidly under high heating rates, releasing a large volume of volatile gases in a short time. Because sufficient porosity has not yet developed to release the gases, internal pressure build up leading to cracking, blistering, and distortion of the fragile brown body (Gonzalez-Gutierrez et al., 2018 ). Furthermore, uncontrolled oxidation during debinding can cause volatile gases to ignite or react excessively with oxygen, resulting in extensive surface oxidation and over-burning (Zissel et al., 2025 ). This phenomenon arises from rapid binder decomposition, excessive oxygen availability, and poor gas diffusion, which trigger localized reactions and structural damage. In addition, incomplete gas diffusion through the limited porosity may generate hot spots with concentrated combustion, further intensifying over-burning effects. Such catastrophic outcomes are consistently reported when solvent-assisted debinding is omitted, as the solvent step is essential for creating interconnected porosity (Basir et al., 2024 ; Hwang & Hsieh, 1996 ) that allows gases to diffuse out gradually during subsequent thermal debinding. Additionally, recent work by Basir et al. ( 2024 ) shows that these solvent-generated pores are essential for efficient binder removal—enabling 99% removal and yielding high-density parts after sintering in yttria-stabilized zirconia/316L systems. These results confirm that a staged debinding strategy is necessary for high-polymer-content feedstocks. Solvent extraction first removes the soluble binder fraction and generates open porosity, while thermal debinding subsequently eliminates the backbone binder throughout the interior. This combined approach ensures complete binder removal, mitigates defect formation, and preserves the integrity of the brown body for sintering. 3.2 Densification analysis Dimensional and mass changes were evaluated across three processing stages: the as-printed FFF green parts, the brown parts obtained after solvent and subsequent thermal debinding, and the final sintered parts. Since solvent-assisted debinding successfully removed the soluble binder fraction and prevented internal cracking, this approach was adopted in the study. Two types of sintering atmospheres were employed: vacuum and argon. Two-dimensional specimens were prepared following ASTM E23 for tensile testing and ASTM D638 TypeV for Charpy impact test. 3.2.1 Dimensional analysis of sintered parts Table 4 summarizes the dimensional changes of the sintered parts under both atmospheres, using the brown parts as the baseline reference. The corresponding results are also presented in graphical form in Fig. 3 (A) for clearer comparison of vacuum- and argon-sintered parts. Vacuum-sintered Charpy specimens (ASTM E23) exhibited shrinkage of − 7.8% in length and − 7.1% in width, while the height remained unchanged. The corresponding volume decreased from 4.93 cm³ (brown part) to 4.22 cm³, representing a − 14.4% reduction. Similarly, vacuum-sintered tensile specimens (ASTM D638 Type V3) showed more pronounced shrinkage, with − 13% in both length and width, while the height remained stable. Their volume decreased from 3.45 cm³ (brown part) to 2.60 cm³, corresponding to a − 24.6% reduction. The obtained 7–13% vacuum-sintered shrinkage lies within the expected range of ~ 6–14% (Go et al., 2024 ; Gonzalez-Gutierrez et al., 2018 ; Kedziora et al., 2022 ; Pellegrini et al., 2024 ) for 17-4PH stainless steel, particularly at intermediate sintering temperatures (≈ 1100–1300°C) where densification in moderate condition (~ 70–85% of theoretical density (TD)). The shrinkage occurred confirming that substantial pore elimination occurred under vacuum conditions. These findings confirm that the present results are consistent with prior studies and reflect moderate densification under vacuum conditions. Argon-sintered samples exhibited dimensional expansion and, in some cases, only minimal shrinkage (≤ 4%). This behavior arises because the argon-sintered environment provides an inert atmosphere that prevents further oxidation but does not remove oxygen already present within the part. During sintering, as pore channels close, trapped oxygen or unreduced oxides can become confined within partially or fully sealed pores, generating internal pressure that can cause dimensional local expansion (swelling), as supported by the EDX results presented in Section 3.4. Table 5 presents the mass of 17-4PH stainless steel specimens at different stages: as-printed green, brown (after debinding), and sintered (Fig. 3 (B)). After solvent debinding, all specimens’ loss approximately 2.7 − 3.7 wt%, indicating consistent with removal of the soluble binder fraction. Vacuum-sintered specimen exhibited a small mass increase of approximately ~ 3 wt%, consistent with uniform shrinkage (7–13%) and isotropic densification, indicating effective pore elimination, following the relationship \(\:\frac{\varDelta\:m}{{m}_{o}}={\rho\:}_{o}\left(\frac{△V}{{V}_{o}}\right)\:\) where densification accounts for the apparent mass increase per unit volume (Kazior, 2023 ). In contrast, argon-sintered specimens showed a larger mass gain of 16–18% due to the formation of an oxide scale during sintering, which follows parabolic oxidation kinetics \(\:\varDelta\:{m}^{2}={k}_{p}t\) , where \(\:\varDelta\:m\) is the mass changes, k p represents the chromium oxide (Cr 2 O 3 ) growth rate constant, indicating formation of approximately 15–20 µm oxide scale thickness (Hryha & Wendel, 2018 , 2019 ) and t is oxidation times. This equation indicates that the mass gain due to oxidation increases with the square root of time, leading to a thicker oxide layer over time. It also correlates with parabolic Cr 2 O 3 scale growth following \(\:\varDelta\:m={k}_{p}{t}^{1/2}\) kinetics where the scale adds mass while preventing inter-particle diffusion through formation of oxide barriers at particle interfaces. The key findings and underlying mechanisms for 17-4PH stainless steel specimens subjected to vacuum and argon sintering are summarized in Table 6 . Table 4 Dimensional changes of 17-4PH stainless steel specimens after sintering Specimen Sintering Atmosphere Length, L (cm) Width, W (cm) Height, H (cm) Volume, V (cm 3 ) ∆L (%) ∆W (%) ∆H (%) ∆V (%) ASTM E23 (For Charpy test) Initial 6.40 0.70 1.10 4.93 − − − − Vacuum 5.90 0.65 1.10 4.22 −7.8 −7.1 0.0 −14.4 Argon 6.50 0.80 1.20 6.24 1.6 14.3 9.1 26.6 ASTM D638 Type V (For Tensile test) Initial 7.50 1.15 0.40 3.45 − − − − Vacuum 6.50 1.00 0.40 2.60 −13.3 −13.0 0.0 −24.6 Argon 7.50 1.10 0.50 4.13 0 −4.3 25 19.6 Table 5 Mass of 17-4PH stainless steel specimens after printing, debinding and sintering, relative to the as-printed green, brown and sintered-parts Specimen ASTM E23 ASTM D638 Type V Mass, m (g) ∆m (%) Mass, m (g) ∆m (%) Green part (After printing) 25.586 − 14.416 − Brown part (After debinding) Vacuum 24.908 −2.6 13.886 −3.7 Argon 25.095 −1.9 13.953 −3.2 Sintered part Vacuum 25.610 2.8 14.399 3.7 Argon 29.850 18.9 16.285 16.7 Table 6 Summary of findings and underlying mechanisms for vacuum-sintered and argon-sintered 17-4PH stainless steel specimens. Atmosphere Dimensional changes Mass changes Mechanism Vacuum-sintered 7–13% uniform shrinkage Small net mass gain ( ~ + 3%) Vacuum extract the oxygen in the furnace and within the parts, allowing grain-boundaries diffusion close the void and attribute affective pore elimination. Argon-sintered Swelling (19.6% increase in volume) Large net mass gain ( ~ + 16%) Argon prevents further oxidation during sintering, but residual oxygen can still occupy pores and become physically enclosed once particle necks close, counteracting densification. This trapped oxygen reacts with chromium to form a Cr₂O₃ oxide scale, increasing the part’s mass and locking oxide films at particle boundaries. 3.3 Microstructural Characterization In order to investigate the microstructural result during sintering, including necking formation, pore morphology, and particle coalescence which are critical for understanding mechanical integrity and sintering efficiency, scanning electron microscopy (SEM) was performed on vacuum-sintered and argon-sintered specimen that had undergone prior solvent followed by thermal debinding. Micrographs were captured at 10,000× magnification using an acceleration voltage of 15.0 kV and a working distance of 10.5 mm. Particle and pore dimensions were measured using the SEM calibration scale (1 cm = 5 µm). The neck formation between particles exhibited a clear dependence on the sintering atmosphere. Vacuum-sintered specimens showed a neck growth ratio exceeding unity (1.06), indicating progression beyond initial particle contact to intermediate-stage sintering where neck enlargement promotes the development of continuous metallic pathways between adjacent particles, as evidenced in Fig. 4 (A), Observation 1. According to classical sintering theory (Mazlan et al., 2023 ), values > 1.0 suggest that surface diffusion and grain boundary migration have progressed sufficiently to enable load-bearing connections. This reflects effective particle coalescence and densification facilitated by unhindered atomic diffusion. In contrast, argon-sintered specimens displayed a lower neck growth ratio (0.75), characteristic of arrested sintering at the initial contact stage. The reduced neck growth under argon is attributed to residual oxygen and oxide layers at particle interfaces, which hinder atomic transport, combined with internal gas pressure that opposes capillary-driven densification. Consequently, argon-sintered specimens exhibited higher porosity (44.35%) and lower densification (55.65%) compared to vacuum-sintered samples. This comparison highlights that vacuum provides an environment conducive to neck growth and intermediate-stage densification, whereas argon, although inert, can limit neck development due to oxide barriers and restricted atomic mobility. In terms of pore morphology, vacuum-sintered specimens exhibited the pores in exhibited a spherical morphology with an average diameter of 6.31 µm, indicative of surface energy minimization typical of advancing densification (Fig. 4 (A), Observation 2). Pore rounding occurs when sufficient atomic mobility exists to minimize surface curvature based on Young-Laplace equation \(\:\varDelta\:P=2\gamma\:/r\) , where \(\:\gamma\:\) is surface energy and r is pore radius (Şahin et al., 2022 ). The calculated localized porosity of 25.6% corresponds to a densification level of 74.4%, confirming that partial sintering had occurred while significant residual porosity remained. During sintering, pores naturally tend to round to minimize surface energy. However, if atomic diffusion is limited, this rounding is hindered, and pores remain angular ((Fig. 4 (A), Observation 3). Accordingly, argon-sintered specimens retained angular pore morphologies, indicating restricted atomic mobility and limited surface energy minimization. According to Herring's scaling law which describes the relationship between pore size and diffusion distances required for spheroidization; larger pores require longer diffusion paths to become rounded. Pore spheroidization requires diffusion distances proportional to pore size, but oxide films at particle interfaces impede the necessary mass transport (Pellegrini et al., 2024 ). The larger, more interconnected pores suggest that densification was hindered and the sintering process terminated before pore isolation could occur (Fig. 4 (B)). The higher porosity (44.35%) and lower densification (55.65%) in argon-sintered specimens highlight the combined effects of oxide barrier formation and restricted atomic transport, which limit neck growth and overall densification. As summarized in Table 7 , vacuum-sintered specimens achieved superior bonding and densification compared to argon-sintered ones. Vacuum sintering promoted neck growth, pore rounding, and effective densification, while argon sintering was less effective due to restricted diffusion. Specifically, vacuum-sintered samples showed a higher neck growth ratio (1.06 vs. 0.75), smaller particle size (15.38 µm vs. 19.48 µm), and lower porosity (25.60% vs. 44.35%), leading to higher densification (74.40% vs. 55.65%). In addition, they contained smaller, rounded pores, whereas argon-sintered specimens retained irregular pores and weaker particle bonding. Table 7 Comparison of microstructural parameters for vacuum-sintered and argon-sintered 17-4PH stainless steel specimens. Item Vacuum-sintered Argon-sintered Average neck length (µm) 16.250 14.61 Average particle diameter (µm) 15.375 19.48 Neck growth ratio 1.06 0.75 Average pore diameter (µm) 6.31 − Total pore area (µm 2 ) 63.97 − Average particle cross-sectional area (µm 2 ) 185.67 − Calculated porosity (%) 25.60 44.35 Corresponding densification (%) 74.40 55.65 3.4 Energy-Dispersive X-ray Spectroscopy (EDX) analysis The elemental composition of the near-surface region was verified by conducting EDX analysis on specimens sintered under both vacuum and argon conditions. The obtained results are presented in Fig. 4 , and a detailed comparison is provided in Table 8 . The presence of the expected 17 − 4 PH alloying elements (Fe, Cr, and Nb) in vacuum-sintered specimen confirmed that the alloy identity was preserved after sintering under vacuum conditions. For the 17-4PH bulk composition is dominated by Fe (~ 60–70 wt%) together with Cr, Ni, Cu, and Nb as alloying elements. In contrast, the EDX measurement of the vacuum-sintered specimen revealed a significantly lower Fe content (12.44 wt%). This apparent discrepancy arises from the limitation of EDX as a near-surface analytical technique, with a typical penetration depth of only ~ 1–2 µm. In porous microstructures, the interaction volume of the electron beam is further reduced by the presence of pore walls and voids, causing the analysis to underrepresent the true matrix composition. Consequently, the deviation between the bulk composition and the EDX results does not indicate elemental depletion but rather reflects the influence of porosity and the shallow sampling depth of EDX (He et al., 2018 ). EDX analysis revealed a significantly higher carbon concentration on the surface (1.99wt%), indicating enrichment with carbon-based residues from the polymeric binder, in agreement with the findings from Tosto et al. ( 2021 ). The carbon content increased from 0.07 wt% before sintering to 27.89 wt% after sintering, highlighting that the binder was not completely removed during the process. Under vacuum conditions, rapid gas evolution can result in the entrapment of carbonaceous residues within closed pores, thereby preventing their complete elimination. This phenomenon has been reported in previous studies, which demonstrated that vacuum processing is prone to carbon retention in the microstructure (Singh et al., 2021 ). The presence of residual carbon is particularly significant, as it may locally modify the alloy chemistry, deteriorate corrosion resistance, and the influence of the interlayer bonding strength which compromise the mechanical performance of the sintered component (Tosto et al., 2021 ). The detected phosphorus content (2.06 wt%) is likely derived from binder additives and may represent a potential source of embrittlement, as phosphorus segregation to grain boundaries is known to reduce cohesive strength (Coulson, 2018 ). In contrast, the low oxygen content and the preservation of the chromium signal showed that oxidation was minimal, thereby validating the protective effect of the vacuum atmosphere during sintering. For the argon-sintered specimen, the high oxygen content and the absence of key alloying elements such as Cr and Nb indicate surface oxidation and incomplete sintering reactions. The substantial oxygen level (4.70 wt%) observed despite the nominally inert atmosphere showed that residual oxygen in the furnace system (estimated at < 0.1%) was sufficient to oxidize chromium at sintering temperatures. Thermodynamic calculations support this observation, as the formation of Cr₂O₃ has a Gibbs free energy of approximately − 540 kJ/mol at 1100°C, providing a strong driving force for oxidation even under low oxygen partial pressures (Zhu et al., 2023 ). The absence of Cr, Nb, and Ni signals in the EDX spectra is therefore more plausibly attributed to masking by surface oxide layers rather than elemental depletion. Oxide scales with thicknesses of 2–5 µm can effectively attenuate the signals from the underlying metallic phases, which is consistent with the low total mass return (23.28%) recorded (Hryha & Wendel, 2019 ). The formation of such oxide barriers explains the arrested sintering behaviour and the deterioration of mechanical properties subsequently observed. Table 8 EDX elemental composition of vacuum- and argon-sintered specimen Element Vacuum-sintered Argon-sintered Mass (%) Atom (%) Notes Mass (%) Atom (%) Notes Fe 12.44 37.46 Base metal; signal likely affected by surface porosity 14.81 37.55 Base metal; surface signal captured Cr 5.04 16.29 Corrosion-resistant element 0.00 0.00 Not detected; below detection or oxidized Nb 2.87 5.20 Strengthening alloying element 0.00 0.00 Not detected; below detection or oxidized P 2.06 11.21 May cause brittleness 0.00 0.00 Not detected; below detection or oxidized C 1.99 27.89 Indicate residual carbon from binder 0.64 7.52 Residual binder presence S 0.24 1.28 Potential embrittlement risk 2.89 12.78 Impurity; possible embrittlement Cu 0.19 0.49 Minor contamination 0.22 0.48 Minor contamination Ni 0.06 0.16 Expected in 17-4PH but very low value here 0.00 0.00 Not detected; below detection or oxidized O − − − 4.70 41.62 Indicates surface oxidation Mn − − − 0.02 0.05 Tracing alloy element 3.5 Mechanical characterization Tensile and Charpy impact tests were conducted to evaluate the mechanical properties of FFF-printed 17 − 4 PH stainless steel specimens sintered under two different atmospheres: argon and vacuum. 3.5.1 Tensile test Using Image J, the porosity of the vacuum-sintered specimen was determined to be 25.6%, corresponding to a real load-bearing area of 14.06 mm², slightly less than the measured 15 mm². Applying a correction factor of approximately 1.067, the adjusted tensile properties were 119.8 GPa for Young’s modulus, 43.3 MPa for yield strength, and 179.0 MPa for ultimate tensile strength. In comparison, the argon-sintered specimen exhibited a higher porosity of 44.35%, resulting in a real load-bearing area of 10.52 mm². With a correction factor of about 1.426, the corresponding tensile properties were 68.4 GPa, 2.17 MPa, and 5.53 MPa for Young’s modulus, yield strength, and ultimate tensile strength, respectively. Even after accounting for these corrections, the measured values remained substantially lower than those reported by Markforged, likely due to the presence of porosity acting as stress concentrators, which promoted premature failure (Tosto et al., 2021 ). FFF specimens exhibited a similar reduction in mechanical properties relative to injection-molded samples (Cicala et al., 2018 ; Tosto et al., 2020 ; Tronvoll et al., 2018 ) The vacuum-sintered specimens exhibited yielding behaviour, with a yield strength of 40.6 MPa and measurable ductility (0.629% elongation), indicating the successful development of metallic bonding. This pattern is indicative of intermediate sintering, when particle interfaces achieve enough cohesion to enable partial plastic deformation before failing (Wu et al., 2002 ). The smooth progression of the stress–strain curve further confirms a relatively uniform load distribution through the developed neck network. By contrast, the argon-sintered specimens failed prematurely in a brittle manner, showing negligible ductility (0.014% elongation). Their irregular and jagged stress–strain profile indicates non-uniform load transfer and the progressive fracture of individual particle contacts, behaviour associated with oxide barrier formation that obstructs metallurgical bonding (Brytan, 2017 ). The tensile strength of the vacuum-sintered specimens (167.86 MPa) represents approximately 15% of the tensile strength of wrought 17 − 4 PH stainless steel (~ 1100 MPa) (Table 9 ), which is consistent with the expectations for early-stage sintering at sub-optimal temperatures. The significant impact in tensile response between vacuum and argon conditions underscores the critical influence of sintering atmosphere. Vacuum sintering facilitated bonding and densification, yielding improved tensile performance, whereas argon sintering promoted oxidation and incomplete binder removal, leading to severe embrittlement. The tensile properties, as derived from the stress–strain curves shown in Fig. 6 , are compared, and a summary of the mechanical performance under both sintering conditions is presented in Table 10 . Table 9 Material properties as indicated by the manufacturer’s data sheet of Markforged 17-4PH SS (Kedziora et al., 2022 ) Parameter 17-4PH (XY) 1 Yield strength (MPa) 800 Ultimate tensile strength (MPa) 1050 Modulus 170 Elongation (%) 5 Hardness 30 HRC 1 No values for the Z direction are given by the manufacturer. The data were extracted from the technical data sheet released by Desktop Metal with their Studio System™. In order to compare the results of this study with other works on 17 − 4 PH FFF specimens, Table 10 summarizes the details, and the normalized data are presented in graphical form (Fig. 7 ). The normalization was performed by dividing the obtained values by the volume of the initial standard geometry, assuming a bar-shaped specimen defined by its length, width, and thickness. Vacuum sintering significantly enhances the normalized yield strength, achieving an improvement of approximately 25 times compared to argon-sintered specimens. However, the yield strength of vacuum-sintered parts remains lower than values reported in other FFF studies. Specimens sintered in argon exhibit minimal yield strength, likely due to poor densification and oxidation during processing. Abe et al. ( 2021 ) reported a normalized ultimate strength of 1.0 MPa, ~ 11 times higher than the vacuum-sintered specimens in this work while other studies report values in the range of 0.1–0.4 MPa. The excellence performance in Abe et al. is attributed to their custom fabrication of the binder system and optimized debinding and sintering procedures. Regarding normalized modulus, vacuum-sintered specimens in this study achieved ~ 0.046 GPa, the highest among the compared studies. This indicates that vacuum sintering substantially improves stiffness and modulus relative to argon-sintered specimens and prior FFF work, suggesting enhanced particle bonding. While vacuum-sintered specimens exhibit limited ductility, their performance remains within the range reported in other studies. Table 10 Overview of tensile properties for 17 − 4 PH SS produced using FFF additive manufacturing First author AM type Binder Powder (%) Specimen dimension (mm) Debinding Sintering YieldStr. (MPa) Ultimate Tensile Str. (MPa) Modulus (GPa) Elongation (%) Strain at break (Zhang & Roch, 2022 ) FFF PTB 64 (Purity > 98% D50 28 µm) Tensile L: 100, W: 10, G: 32, H: 6 Solvent: Acetone at 50°C for 5h 1360°C of 1h, quenched to RT under N 2 gas flow (30 l/ min) + annealed at 550°C for 4h 1007 1212 175 5–9.5 (Romero et al., 2025 ) FFF PTB Not disclosed Tensile L: 150, W: 20, H: 3 Charpy L: 55, G: 27.5, H: 10 Solvent debinding using Opteon™ SF79 for 12–13 h Sinter-1 furnace under argon with 3% hydrogen to limit oxidation. Sintering occurred near 1100 ◦C over a 27-h cycle 780 1141 149 2.4 (Kedziora et al., 2022 ) FFF PTB Not disclosed Tensile L: 110, W:13, G: 38, H: 3 Charpy L: 55, G: 27.5, H: 10 In-house with the default parameters recommended by Markforged In-house with the default parameters recommended by Markforged 441.0 ± 55.4 495.9 ± 77.0 142 ± 65 0.4 ± 0.1 (Abe et al., 2021 ) FFF POM, PP, PW 60 Tensile L: 44.7, W:10.47, G: 24.7, H: 2 Thermal: 600°C in N 2 gas for 2hr 1280°C for 2 h (Ar gas) - 880 - 2.4 (Tosto et al., 2021 ) FFF PTB Not disclosed Tensile L: 100, W: 10, G: 32, H: 6 Charpy L: 55, G: 27.5, H:10 In-house with the default parameters recommended by Markforged In-house with the default parameters recommended by Markforged 443.00 ± 6.90 497.40 ± 9.90 108.00 ± 6.90 0.79 ± 0.05 This work FFF PTB 60 Tensile L: 63.5, W: 9.53, G: 6.53, H: 4 Charpy L: 55, G: 27.5, H:10 Thermal or Solvent debinding 1100°C for 3 h (Vacuum) 40.63 167.86 112.34 0.629 This work FFF PTB 60 Tensile L: 63.5, W: 9.53, G: 6.53, H: 4 Charpy L: 55, G: 27.5, H:10 Thermal or Solvent debinding 1100°C for 3 h (Argon gas) 1.52 3.88 48 0.014 PTB = proprietary thermoplastic binder (unspecified composition), polyoxymethylene (POM), polypropylene (PP), and paraffin wax (PW). 3.5.2 Charpy impact test The most unexpected finding in the Charpy impact test was that the vacuum-sintered specimen fractured catastrophically, completely fragmenting and failed to produce a measurable impact resistance; therefore, no results could be reported. Similarly, Kedziora et al. ( 2022 ) reported no measurable values for FFF-printed specimens in their study. In contrast, the argon-sintered sample absorbed 0.7 J before fracturing. Although the absorbed energy was low, the specimen remained structurally intact, consistent with a brittle fracture influenced by porosity and surface oxidation. This paradoxical result highlights the difference between quasi-static and dynamic loading: while vacuum sintering improved tensile properties due to better densification, it also introduced processing-related defects. The presence of residual carbon from incomplete binder removal can lead to carbide precipitation or can react with chromium in 17-4PH, forming chromium carbides at grain boundaries. This local chromium depletion weakens grain boundaries, causing intergranular embrittlement. Vacuum sintering increased shrinkage and tensile properties under quasi-static load, however, toughness depends on defect tolerance. With pre-existing voids and carbon-induced embrittlement a microstructure prone to cleavage-type cracks, where cracks propagate rapidly along crystallographic planes. This made the specimen incapable of absorbing dynamic impact energy, leading to catastrophic fragmentation with no measurable toughness (Fig. 8 ). Densification in argon-sintered specimens is slightly lower than in vacuum-sintered samples, resulting in reduced tensile strength. However, the residual porosity is more uniform and less severe, and internal stresses are lower due to gentler binder burnout. These factors allow the specimen to absorb energy during the Charpy impact test. Overall, the results indicate a trade-off between sintering atmospheres. 4 Conclusion This study investigated 17-4PH stainless steel parts fabricated via FFF, focusing on the effects of different debinding methods (solvent and thermal) and sintering atmospheres (vacuum and argon). Thermal debinding alone was found unsuitable for this filament; a sequential approach combining solvent debinding with controlled thermal profiling is recommended. Vacuum sintering promoted effective densification, with 7–13% linear shrinkage and 74.4% relative density, while argon-sintered specimens exhibited minimal shrinkage (~ 1%) and lower relative density (55.65%). Vacuum sintering facilitated bonding and densification, yielding improved tensile performance, whereas argon sintering promoted oxidation and incomplete binder removal, leading to severe embrittlement. Vacuum sintering facilitated particle bonding and densification, achieving a porosity of 25.6% and resulting in enhanced tensile performance. However, toughness was limited due to pre-existing voids and carbon-induced embrittlement, which promoted cleavage-type crack propagation and catastrophic fragmentation under dynamic loading. In contrast, argon-sintered specimens exhibited higher porosity (44.35%), lower densification, and reduced tensile strength, but their more uniform residual porosity and lower internal stresses from gentler binder burnout allowed them to absorb energy during Charpy impact testing. Overall, these results highlight a trade-off between sintering atmospheres: vacuum sintering maximizes strength and stiffness, whereas argon sintering improves energy absorption and reduces brittleness. This study provides critical guidance for selecting processing routes in FFF 17-4PH components to balance mechanical performance and structural integrity. Declarations Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Contribution The author wrote the main manuscript text. Other co-author will be include later. 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(2022). Fused filament fabrication and sintering of 17-4PH stainless steel. Manufacturing Letters , 33 , 29-32. https://doi.org/10.1016/j.mfglet.2022.06.004 Zhu, B., Li, R., Yuan, T., Li, W., Cai, D., & Kang, N. (2025). Metal binder jetting additive manufacturing: An overview of the process, materials and reinforcement methods. Journal of Alloys and Compounds , 1037 , 182196. https://doi.org/10.1016/j.jallcom.2025.182196 Zhu, P., He, X., Guan, H., Zhang, Z., Zhang, T., & Qu, X. (2023). Investigation on the Attainment of High-Density 316L Stainless Steel with Selective Laser Sintering. Materials (Basel) , 17 (1). https://doi.org/10.3390/ma17010110 Zissel, K., Bernardo, E., Forêt, P., & Hryha, E. (2025). Impact of oxygen content on debinding of binder jetted 17-4 PH stainless steel: Part II – Sintering. Powder Metallurgy , 68 (1), 16-28. https://doi.org/10.1177/00325899241307871 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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Ahmad","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyklEQVRIiWNgGAWjYJCCDyDCgIGxAcIiAjDOgGkBsgxI0sLAwMxDjBZzidyHDT/33JM3Zz/c9ti27U80g9gZ/PosZ6QbNvY8Kzbc2ZPYbpzbZpDbIJ2DX4vBjTT2BzwHEhg3HEhskyZWC2PjnwMJ9hvOP2yTtiRWSzPQlsQNN4C2MBKl5cwzxmaZAwnJG248bJPsOQf0jnRaAX4tx4EOe3MgwXbD+fRnEj/K5HL7pZM34NWCCdgYOIiLT2TA/oBkLaNgFIyCUTCsAQCODkqcbYgIWwAAAABJRU5ErkJggg==","orcid":"","institution":"Universiti Teknologi Malaysia","correspondingAuthor":true,"prefix":"","firstName":"Nur","middleName":"Farrahain Nadia","lastName":"Ahmad","suffix":""}],"badges":[],"createdAt":"2025-10-10 15:38:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7828599/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7828599/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":95197958,"identity":"f7510acc-391c-43d6-9e98-73e711a264c9","added_by":"auto","created_at":"2025-11-05 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16:33:43","extension":"html","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":186678,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/80632525f0d99d3fef8a323c.html"},{"id":95197945,"identity":"a050ddca-4176-45e5-ae59-1b9af3cda030","added_by":"auto","created_at":"2025-11-05 11:46:49","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":262724,"visible":true,"origin":"","legend":"\u003cp\u003eTensile specimens (ASTM D638 Type V) and impact specimens (sub-sized, ASTM E23)\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/b1cdfaccefb9a25b19dd7a5b.jpeg"},{"id":95227182,"identity":"2a4438df-9cef-4f4d-83a1-e0f0a6fefc92","added_by":"auto","created_at":"2025-11-05 16:32:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":567373,"visible":true,"origin":"","legend":"\u003cp\u003eFailure of 17-4PH SS green part subjected to direct thermal debinding without a prior solvent-assisted step\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/b177cf579cdf0f1a5220aac8.png"},{"id":95197944,"identity":"447cd529-7dd9-445f-a1f6-c265f9bf3505","added_by":"auto","created_at":"2025-11-05 11:46:49","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":60556,"visible":true,"origin":"","legend":"\u003cp\u003eDimensional and mass changes for 17-4PH stainless steel specimens\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/6e8a6d6816b0cc72f0540a5b.png"},{"id":95228265,"identity":"6811521c-66e8-4ed9-96e6-fdfeac034225","added_by":"auto","created_at":"2025-11-05 16:33:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":574065,"visible":true,"origin":"","legend":"\u003cp\u003eSEM Micrograph of (A) Vacuum-sintered (B) Argon-sintered 17-4PH specimen at 10,000× magnification.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/85d3cea1a11d2cb6480580bf.png"},{"id":95197948,"identity":"866e956a-40d3-422c-89d0-7562bd5354fb","added_by":"auto","created_at":"2025-11-05 11:46:49","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":391734,"visible":true,"origin":"","legend":"\u003cp\u003eElemental Composition by Mass Percentage of Vacuum- and Argon-sintered specimen\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/24ec280d10457574eee691b9.png"},{"id":95197949,"identity":"2d01d53f-218d-4777-8721-a4deb5e59fe6","added_by":"auto","created_at":"2025-11-05 11:46:49","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":355428,"visible":true,"origin":"","legend":"\u003cp\u003eStress-strain curve and its mechanical properties comparison for (a) Yield strength (b) Ultimate tensile strength (c) Young modulus (d) fracture strength of vacuum and argon-sintered 17-4PH\u003c/p\u003e","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/e2b73885161ccf16154cb91f.jpeg"},{"id":95197953,"identity":"b016ef40-0614-4d45-840a-fb3c3b4ed4ba","added_by":"auto","created_at":"2025-11-05 11:46:49","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":120626,"visible":true,"origin":"","legend":"\u003cp\u003eComparison normalized tensile properties of FFF printed 17-4PH\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/88259d5458312938bc3ff9bd.png"},{"id":95197956,"identity":"978da4e3-e60f-4b5f-be9e-446d1460e40b","added_by":"auto","created_at":"2025-11-05 11:46:50","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":241522,"visible":true,"origin":"","legend":"\u003cp\u003eFractured Charpy Sample Sintered in Vacuum Atmosphere Showing Brittle Failure and Surface Cracking\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/98fe8d9a4b4b087410e10910.png"},{"id":96990759,"identity":"8c17693c-435e-4708-ba8c-4c44d585f7db","added_by":"auto","created_at":"2025-11-28 11:09:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4225114,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7828599/v1/5b8efb8b-3f3b-4a62-bea1-b072e69d1b6c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of Debinding Method and Sintering Atmosphere on Fused Filament Fabrication Printed 17-4PH Stainless Steel at Intermediate Sintering Temperatures","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eMetal Injection Molding (MIM) is commonly used as an alternative to conventional manufacturing methods such as casting, welding, and even machining, particularly for producing metal complex-shaped components. However, from a manufacturing perspective, MIM can be both time-consuming and expensive, especially for small production runs (Bankapalli et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). One of major limitations in MIM is the need for a dedicated mold for each part design. Designing and manufacturing a new mold can take weeks or even months, and any design changes require a completely new mold, further extending lead times and escalating costs (increase cost per unit). These delays can disrupt production schedules and increase overall manufacturing expenses, particularly when tight deadlines must be met. To address these limitations, Metal Additive Manufacturing (MAM) has emerged as a promising solution, offering superior design flexibility, shorter lead times, and potential cost advantages for low- to medium-volume production (Armstrong et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). There are several options of metal AM (ISO/ASTM 52900) like powder bed fusion (PBF), binder jetting (BJ), directed energy deposition (DED) and material extrusion (ME) technologies (Cao et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Tebianian et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). PBF selectively melts or sinters thin powder layers using a high-energy source, enabling near-full density, high-resolution parts with excellent mechanical properties (Gong et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Madhavadas et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). BJ deposits a liquid binder onto a powder bed layer by layer, with the green parts subsequently strengthened through post-processing, making it suitable for large, low-cost, and functionally integrated components (Lores Erazo et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Zhu et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). DED feeds metal powder or wire directly into a melt pool generated by a laser, electron beam, or plasma arc, allowing large build volumes than PBF and efficient component repair (\u0026Ouml;zel et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Svetlizky et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In ME, semi-liquid, semi-solid, or solid form feedstock are extruded through a nozzle and deposited onto a substrate in a controlled manner (Suwanpreecha \u0026amp; Manonukul, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2022b\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWhile AM technologies offer geometric freedom in producing metallic parts, they face key drawbacks, including high capital cost and operational cost (due to expensive raw powders, metal powder quality control via gas or plasma atomization techniques (S\u0026aelig;terb\u0026oslash; \u0026amp; Solvang, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) and energy demand) (Strong et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), strict safety requirements, and microstructural variations from rapid thermal cycling that affect final mechanical properties (Kok et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) include residual stresses, thermal cracks, and anisotropy (LeBrun et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). To address these challenges, researchers and industry are developing additive manufacturing processes that produce metallic components more affordably and sustainably. Fused Filament Fabrication (FFF) is categorized under material extrusion-based techniques, a developed technology that use the existing plastic FFF technology to metal. In metal FFF, a metal powder (mixed with a thermoplastic binder) filament is extruded to form a green part, can then be transformed into a dense metal part using debinding and sintering cycles. Debinding to remove the binder, and finally, high temperature sintering to densify the metal (Jacob et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Singh et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). This procedure provides one of the more accessible and secure beginnings into metal AM, as the powder particle is encapsulated in a polymer, creating a lower risk of powder handling (Costa et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Metal FFF is increasingly recognized as a convenient and cost-effective approach for prototyping and low-volume metal part production, though with the trade-offs of requiring a secondary sintering step and experiencing considerable shrinkage during densification (L\u0026eacute;onard \u0026amp; Tammas-Williams, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e17-4PH is a precipitation-hardened martensitic stainless steel is well-known due to its outstanding strength and resistance to corrosion (Garc\u0026iacute;a-Hern\u0026aacute;ndez et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Zhang \u0026amp; Roch, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), driving its widespread use in sectors such as marine, petrochemical, nuclear, and aerospace (Suwanpreecha \u0026amp; Manonukul, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2022a\u003c/span\u003e). Conventional manufacturing and post-processing of 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel can achieve properties suitable for industrial applications; however, due to its high hardness, 17-4PH steel exhibits poor machinability, making it challenging to shape into complex structures (Joo et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Sivaiah \u0026amp; Chakradhar, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) and exhibit significant variance in microstructure (Lai et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Research on FFF of 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel is still limited. Tosto et al. (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) highlighted the lack of studies on FFF-printed 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH,and Jones et al. (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) reviewed the mechanical properties of 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH parts produced by additive manufacturing, focusing on Markforged\u0026rsquo;s MetalX\u0026trade;; however, they did not address debinding methods or sintering atmospheres. Moreover, Markforged and other commercial platforms do not disclose binder compositions or detailed processing parameters, leaving a knowledge gap in optimizing post-processing for functional performance.The quality of FFF metal parts depends on feedstock characteristics (such as metal loading, polymer type, and additives) and processing conditions (Jacob et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). However, the effects of debinding methods and sintering atmospheres on densification, microstructure, and mechanical properties of 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH FFF parts are not well understood, representing a key research gap.\u003c/p\u003e\u003cp\u003eTherefore, this study focuses on FFF-printed 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel, specifically investigating debinding methods (solvent and thermal) and sintering atmospheres using vacuum and argon. The effects of these processes on characteristics, including dimensional and mass changes, microstructural evolution, and mechanical properties, are systematically analyzed.\u003c/p\u003e"},{"header":"2 Material and Method","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Sample preparation\u003c/h2\u003e\u003cp\u003eFFF printing was performed using a commercially available 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel filament, consisting of approximately\u0026thinsp;~\u0026thinsp;60 vol% powder metal (\u0026asymp;\u0026thinsp;80 wt%, detail composition Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) with powder particle sizes of 10\u0026ndash;45 \u0026micro;m embedded in a polymer binder system. 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH were printed and sintered in outsourcing using a Metal X printer with a 0.4 mm hard steel nozzle to withstand filament abrasiveness, using a 0.2 mm layer height to balance resolution and build time, followed the printing settings specified by Markforged. Key printing parameters are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eChemical composition of the 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel sample under study\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"11\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElement\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCr\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNi\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCu\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eSi\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMn\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNb\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eC\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eS\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eFe\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComposition (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15\u0026thinsp;\u0026minus;\u0026thinsp;17.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u0026thinsp;\u0026minus;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u0026thinsp;\u0026minus;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (max)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1 (max)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.15\u0026ndash;0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.04 (max)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.03 (max)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eBal.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"11\"\u003eNote: Chromium (Cr); Nickel (Ni); Copper (Cu); Silicon (Si); Manganese (Mn); Niobium (Nb); Carbon (C); Phosphorous (P); Sulfur (S); Iron (Fe)\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eParameter for 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel FFF printing process (Markforged)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRationale\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExtruder temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e250\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eOptimal flow without binder degradation\u003c/p\u003e\u003cp\u003e220\u0026deg;C (Kedziora et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrint bed temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e100\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePromotes adhesion and minimizes warping\u003c/p\u003e\u003cp\u003e115\u0026deg;C (Kedziora et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrinting speed\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 mm/s (perimeters), 40 mm/s (infill)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEnsures proper filament deposition\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInfill\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e100% (solid)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEnsures any porosity is from the process, not design\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInfill pattern\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRectilinear (0\u0026deg;/90\u0026deg; alternating)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCreates fully solid parts\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePerimeters\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u0026ndash;3 outlines\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEnsures clean shape\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCooling\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMinimal or off\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePrevents thermal gradients\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFilament preparation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDried at ~\u0026thinsp;50\u0026deg;C for 4 hours\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRemoves moisture to prevent defects\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eTensile specimens were printed in the ASTM D638 Type V dogbone geometry (n\u0026thinsp;=\u0026thinsp;6 per condition), while impact specimens were sub-sized according to ASTM E23 for Charpy testing (n\u0026thinsp;=\u0026thinsp;6 per condition) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). All samples were produced in the same batch under consistent print runs with identical parameters to ensure uniformity. After printing, the green parts were allowed to cool to room temperature on the build plate before being carefully removed.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Debinding process\u003c/h2\u003e\u003cp\u003eDebinding is carried out to eliminate the binder while preserving the geometry of the green part, and complete removal is required since residual carbon can hinder sintering and deteriorate the final quality. Two debinding method used as variables: solvent debinding and thermal debinding.\u003c/p\u003e\u003cp\u003e\u003cem\u003eSolvent debinding\u003c/em\u003e was carried out by immersing the green parts in a hexane bath at 60\u0026deg;C for 4 h inside a closed glass vessel, with gentle magnetic stirring to ensure uniform exposure. The debinding duration was determined by part thickness, as reported by (Zhang \u0026amp; Roch, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). A targeted mass loss of 3.5\u0026ndash;4 wt% was set as the criterion for effective extraction. After treatment, the specimens (brown parts) exhibited extensive extraction of the soluble binder fraction, while retaining the backbone polymer and metallic powder, resulting in a leaner texture and duller surface finish. After solvent debinding of 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel specimens, the resulting brown parts were air-dried to remove residual hexane, followed by oven drying at 50\u0026deg;C for 2 hours. This step was necessary to minimize internal gas evolution during subsequent heating, thereby reducing the risk of deformation or cracking. The ratio of weight loss in each step to the total weight was used to evaluate the binder removal rate and efficiency throughout the debinding process.\u003c/p\u003e\u003cp\u003e\u003cem\u003eThermal debinding\u003c/em\u003e was carried out in a tube furnace under either argon or vacuum atmosphere to remove the remaining backbone polymer from the binder system. A controlled heating profile was applied, with a ramp rate of 5\u0026deg;C/min from 20\u0026deg;C to 550\u0026deg;C for 96 min, followed by a 45 min dwell (holding time) at the peak temperature. A slower heating rate within the critical temperature range enhances binder removal from the brown parts because it allows sufficient time for the polymer binder to gradually decompose and diffuse out, thereby reducing internal gas pressure. This controlled decomposition minimizes stress concentration, which in turn reducing surface cracking. Additionally, uncontrolled and rapid decomposition of the binder may occur if volatile by-products accumulate within the part, incurring the risk of sudden combustion from trapped gases. This phenomenon not only causes localized overheating but also generates internal pressure, which can damage the part. By promoting gradual gas release, the debinding process prevents abrupt binder degradation and preserves the structural stability of the brown part prior to sintering (Raza et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Supriadi et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Sintering Process\u003c/h2\u003e\u003cp\u003eAfter debinding, the brown parts were sintered two different furnace systems: an OTF-1200X tube furnace for high-vacuum sintering (\u0026lt;\u0026thinsp;5 \u0026times; 10⁻⁵ bar) and a Nabertherm LT 9/11/HA furnace for sintering under an argon atmosphere (constant flow\u0026thinsp;~\u0026thinsp;0.15L/min). The sintering cycle was designed to enhance solid-state diffusion bonding of the 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel particles, besides preventing grain coarsening and unwanted surface reaction. Conventional sintering of 17-4PH stainless steel at 1300\u0026ndash;1350\u0026deg;C entails high energy consumption and environmental impact, prompting interest in intermediate-temperature sintering (~\u0026thinsp;1100\u0026deg;C) to balance densification, dimensional accuracy, and mechanical and corrosion performance with reduced processing costs. All process parameters were standardized to ensure reproducibility, with atmosphere processing condition being the only variable (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSintering constant parameters for FFF-printed 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRationale\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHeating rate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u0026deg;C/min (from 550\u0026deg;C to 1100\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEnsures efficient transition into sintering zone while avoiding overshoot\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSintering hold time\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e180 minutes (3 hours)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAllows for sufficient particle bonding and densification\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCooling rate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFurnace cooling under same atmosphere (no heating)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePrevents thermal shock and controls shrinkage or distortion\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample placement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlumina setters with alumina powder spacing\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePrevents sticking and distortion\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eInitial atmosphere\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArgon flush up to 550\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCarries away binder vapors safely\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe heating rate was set at 10\u0026deg;C/min, start from 550\u0026deg;C (Zhang \u0026amp; Roch, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) to the peak sintering temperature (1100\u0026deg;C). An isothermal holding time was 3 h at 1100\u0026deg;C facilitated particle diffusion and densification. After sintering completed, the specimens were cooled to room temperature within the same furnace and atmosphere (vacuum or argon) to minimize thermal gradients and prevent distortion or microcracking. To preserve part integrity during sintering, the specimens were placed on alumina ceramic setters, with a separating layer of alumina powder to prevent adhesion to the baseplate.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Method of analysis\u003c/h2\u003e\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\u003ch2\u003e2.4.1 Material Characterization\u003c/h2\u003e\u003cp\u003eDimensional and mass changes were evaluated across three processing stages\u0026mdash;the as-printed FFF green parts, the brown parts obtained after solvent and thermal debinding, and the final sintered components\u0026mdash;and subsequently compared and analyzed. This evaluation provides insight into the extent of densification, dimensional stability, material flow, and mass loss during each stage, enabling detection of potential defects such as warping or distortion. Furthermore, monitoring these changes helps correlate processing behavior with the final mechanical performance and structural integrity of the sintered components.\u003c/p\u003e\u003cp\u003eIn order to analyze the internal microstructure of the sintered samples and their composition, microstructural characterization was carried out using optical microscopy (OLYMPUS BX53 M) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) (Hitachi SU8020). Sintered specimens from the vacuum and argon specimen were sectioned to obtain cross-sections using a low-speed diamond saw, mounted in conductive phenolic resin, and polished sequentially with silicon carbide papers (P240\u0026ndash;P1200) followed by diamond suspensions. SEM imaging was at maximum backscattered electron (BSE) mode between 15 kV and about 15 mm working distance, which gave the pore morphology a good depth of field. Porosity percentage was determined as the average of three measurements taken from three distinct areas of each sample, by calculating the area fraction of pores, with an estimated error margin of 1\u0026ndash;2%. Porosity measurements were conducted based on SEM image analysis using threshold-based binarization techniques in ImageJ. The porosity (P) was calculated as the percentage of black (void) pixels to total pixel area, representing pore volume fraction.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\u003ch2\u003e2.4.2 Mechanical characterization\u003c/h2\u003e\u003cp\u003eSintered specimens were fabricated according to ASTM D638 Type V geometry and subjected to uniaxial tensile testing. All tests were conducted using a Shimadzu EZ-X universal testing machine equipped with a 5 kN load cell, at a constant crosshead speed of 5 mm/min, corresponding to an approximate strain rate of 0.002 s⁻\u0026sup1;. Testing was performed at ambient laboratory conditions (~\u0026thinsp;25\u0026deg;C) following the relevant ASTM standards.\u003c/p\u003e\u003cp\u003eFracture toughness was evaluated via Charpy V-notch impact tests in accordance with ASTM E23. Prior to testing, each sintered bar was machined to introduce a standard V-notch. Tests were performed using a pendulum-type Charpy impact tester with a 50 J hammer at room temperature.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"3 Result and Discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.1 \u003cb\u003eDebinding Behavior of 17-4PH Stainless Steel Green Parts\u003c/b\u003e\u003c/h2\u003e\u003cp\u003eSince the as-printed green parts contain approximately 20 vol% polymer binder, debinding process is essential for binder removal in order to allow effective sintering and metallurgical bonding between metal particles while preserving structural integrity (Tafti et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Two debinding method involving solvent debinding and thermal debinding were evaluated. To ensure comparability, the constant parameters across all experiments included the green part geometry and the binder system composition.\u003c/p\u003e\u003cp\u003eA preliminary weight-loss experiment was conducted to validate solvent debinding performance. A green specimen was halved, with one half immersed in room-temperature (RT) hexane and the other in hexane at 60\u0026deg;C. Samples were removed hourly for four hours, dried, and weighed. After four hours of immersion, hexane at 60\u0026deg;C produced a weight loss exceeding 6%, surpassing the target threshold, whereas room-temperature hexane achieved only 4.5% weight loss for binder removal, indicating significantly lower efficiency. Although solvent debinding at 60\u0026deg;C efficiently removes the soluble binder fraction mainly at the surface, its penetration into the interior of the compact is limited by diffusion. As a result, binder extraction occurs more rapidly at the surface while significant amounts of the backbone binder remain trapped inside the part. Solvent treatment alone cannot achieve homogeneous debinding throughout the specimen, which must be decomposed through subsequent controlled thermal debinding to decompose the remaining binder uniformly, prevent internal defects such as blistering, cracking, or warping during sintering and preserve part integrity (Lotfizarei et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Ni et al. (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) similarly reported that solvent-assisted debinding produces an interconnected pore structure that facilitates gas escape and enables efficient thermal removal of residual binder. Based on these findings, a 24-hour immersed in 60\u0026deg;C hexane was adopted as the solvent debinding condition for subsequent thermal debinding for the actual specimen size.\u003c/p\u003e\u003cp\u003eIn contrast, direct thermal debinding led to catastrophic failure, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The specimens exhibited severe over-burning, extensive oxidation, gas-induced internal cracking, and surface blistering. These results underscore the necessity of a solvent-assisted step to enable gradual binder removal and to prevent internal pressure buildup that compromises structural integrity. Thermal debinding alone was therefore unsuitable for 17-4PH stainless steel green parts, primarily due to their high polymer content (~\u0026thinsp;20 vol%). During direct thermal debinding, the ~\u0026thinsp;20 vol% polymer binder present in the green parts decomposes rapidly under high heating rates, releasing a large volume of volatile gases in a short time. Because sufficient porosity has not yet developed to release the gases, internal pressure build up leading to cracking, blistering, and distortion of the fragile brown body (Gonzalez-Gutierrez et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Furthermore, uncontrolled oxidation during debinding can cause volatile gases to ignite or react excessively with oxygen, resulting in extensive surface oxidation and over-burning (Zissel et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). This phenomenon arises from rapid binder decomposition, excessive oxygen availability, and poor gas diffusion, which trigger localized reactions and structural damage. In addition, incomplete gas diffusion through the limited porosity may generate hot spots with concentrated combustion, further intensifying over-burning effects. Such catastrophic outcomes are consistently reported when solvent-assisted debinding is omitted, as the solvent step is essential for creating interconnected porosity (Basir et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Hwang \u0026amp; Hsieh, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e1996\u003c/span\u003e) that allows gases to diffuse out gradually during subsequent thermal debinding. Additionally, recent work by Basir et al. (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) shows that these solvent-generated pores are essential for efficient binder removal\u0026mdash;enabling 99% removal and yielding high-density parts after sintering in yttria-stabilized zirconia/316L systems.\u003c/p\u003e\u003cp\u003eThese results confirm that a staged debinding strategy is necessary for high-polymer-content feedstocks. Solvent extraction first removes the soluble binder fraction and generates open porosity, while thermal debinding subsequently eliminates the backbone binder throughout the interior. This combined approach ensures complete binder removal, mitigates defect formation, and preserves the integrity of the brown body for sintering.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Densification analysis\u003c/h2\u003e\u003cp\u003eDimensional and mass changes were evaluated across three processing stages: the as-printed FFF green parts, the brown parts obtained after solvent and subsequent thermal debinding, and the final sintered parts. Since solvent-assisted debinding successfully removed the soluble binder fraction and prevented internal cracking, this approach was adopted in the study. Two types of sintering atmospheres were employed: vacuum and argon. Two-dimensional specimens were prepared following ASTM E23 for tensile testing and ASTM D638 TypeV for Charpy impact test.\u003c/p\u003e\u003cdiv id=\"Sec12\" class=\"Section3\"\u003e\u003ch2\u003e3.2.1 Dimensional analysis of sintered parts\u003c/h2\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e summarizes the dimensional changes of the sintered parts under both atmospheres, using the brown parts as the baseline reference. The corresponding results are also presented in graphical form in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(A) for clearer comparison of vacuum- and argon-sintered parts. Vacuum-sintered Charpy specimens (ASTM E23) exhibited shrinkage of \u0026minus;\u0026thinsp;7.8% in length and \u0026minus;\u0026thinsp;7.1% in width, while the height remained unchanged. The corresponding volume decreased from 4.93 cm\u0026sup3; (brown part) to 4.22 cm\u0026sup3;, representing a \u0026minus;\u0026thinsp;14.4% reduction. Similarly, vacuum-sintered tensile specimens (ASTM D638 Type V3) showed more pronounced shrinkage, with \u0026minus;\u0026thinsp;13% in both length and width, while the height remained stable. Their volume decreased from 3.45 cm\u0026sup3; (brown part) to 2.60 cm\u0026sup3;, corresponding to a \u0026minus;\u0026thinsp;24.6% reduction. The obtained 7\u0026ndash;13% vacuum-sintered shrinkage lies within the expected range of ~\u0026thinsp;6\u0026ndash;14% (Go et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Gonzalez-Gutierrez et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Kedziora et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Pellegrini et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) for 17-4PH stainless steel, particularly at intermediate sintering temperatures (\u0026asymp;\u0026thinsp;1100\u0026ndash;1300\u0026deg;C) where densification in moderate condition (~\u0026thinsp;70\u0026ndash;85% of theoretical density (TD)). The shrinkage occurred confirming that substantial pore elimination occurred under vacuum conditions. These findings confirm that the present results are consistent with prior studies and reflect moderate densification under vacuum conditions. Argon-sintered samples exhibited dimensional expansion and, in some cases, only minimal shrinkage (\u0026le;\u0026thinsp;4%). This behavior arises because the argon-sintered environment provides an inert atmosphere that prevents further oxidation but does not remove oxygen already present within the part. During sintering, as pore channels close, trapped oxygen or unreduced oxides can become confined within partially or fully sealed pores, generating internal pressure that can cause dimensional local expansion (swelling), as supported by the EDX results presented in Section 3.4.\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e presents the mass of 17-4PH stainless steel specimens at different stages: as-printed green, brown (after debinding), and sintered (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(B)). After solvent debinding, all specimens\u0026rsquo; loss approximately 2.7\u0026thinsp;\u0026minus;\u0026thinsp;3.7 wt%, indicating consistent with removal of the soluble binder fraction. Vacuum-sintered specimen exhibited a small mass increase of approximately\u0026thinsp;~\u0026thinsp;3 wt%, consistent with uniform shrinkage (7\u0026ndash;13%) and isotropic densification, indicating effective pore elimination, following the relationship \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\varDelta\\:m}{{m}_{o}}={\\rho\\:}_{o}\\left(\\frac{△V}{{V}_{o}}\\right)\\:\\)\u003c/span\u003e\u003c/span\u003ewhere densification accounts for the apparent mass increase per unit volume (Kazior, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). In contrast, argon-sintered specimens showed a larger mass gain of 16\u0026ndash;18% due to the formation of an oxide scale during sintering, which follows parabolic oxidation kinetics \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:{m}^{2}={k}_{p}t\\)\u003c/span\u003e\u003c/span\u003e, where \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:m\\)\u003c/span\u003e\u003c/span\u003e is the mass changes, \u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e represents the chromium oxide (Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) growth rate constant, indicating formation of approximately 15\u0026ndash;20 \u0026micro;m oxide scale thickness (Hryha \u0026amp; Wendel, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2018\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) and \u003cem\u003et\u003c/em\u003e is oxidation times. This equation indicates that the mass gain due to oxidation increases with the square root of time, leading to a thicker oxide layer over time. It also correlates with parabolic Cr\u003csup\u003e2\u003c/sup\u003eO\u003csup\u003e3\u003c/sup\u003e scale growth following \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:m={k}_{p}{t}^{1/2}\\)\u003c/span\u003e\u003c/span\u003e kinetics where the scale adds mass while preventing inter-particle diffusion through formation of oxide barriers at particle interfaces.\u003c/p\u003e\u003cp\u003eThe key findings and underlying mechanisms for 17-4PH stainless steel specimens subjected to vacuum and argon sintering are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDimensional changes of 17-4PH stainless steel specimens after sintering\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecimen\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSintering Atmosphere\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLength, L (cm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eWidth, W (cm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eHeight, H (cm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eVolume, V (cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e∆L (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e∆W (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003e∆H (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003e∆V (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eASTM E23\u003c/b\u003e (For Charpy test)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e6.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e4.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVacuum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e5.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e4.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026minus;7.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u0026minus;7.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026minus;14.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArgon\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e6.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e6.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e14.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e9.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e26.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cb\u003eASTM D638\u003c/b\u003e Type V (For Tensile test)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e3.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVacuum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e6.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e2.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026minus;13.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u0026minus;13.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026minus;24.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArgon\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e4.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u0026minus;4.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e19.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMass of 17-4PH stainless steel specimens after printing, debinding and sintering, relative to the as-printed green, brown and sintered-parts\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c2\" namest=\"c1\" rowspan=\"2\"\u003e\u003cp\u003eSpecimen\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eASTM E23\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003eASTM D638 Type V\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMass, m (g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e∆m (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMass, m (g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e∆m (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eGreen part (After printing)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25.586\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e14.416\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eBrown part (After debinding)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVacuum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24.908\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e13.886\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026minus;3.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArgon\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25.095\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;1.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e13.953\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026minus;3.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eSintered part\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVacuum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25.610\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e14.399\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e3.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArgon\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e29.850\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e18.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e16.285\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e16.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of findings and underlying mechanisms for vacuum-sintered and argon-sintered 17-4PH stainless steel specimens.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAtmosphere\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDimensional changes\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMass changes\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMechanism\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVacuum-sintered\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7\u0026ndash;13% uniform shrinkage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSmall net mass gain (\u0026thinsp;~\u0026thinsp;+\u0026thinsp;3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eVacuum extract the oxygen in the furnace and within the parts, allowing grain-boundaries diffusion close the void and attribute affective pore elimination.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eArgon-sintered\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSwelling (19.6% increase in volume)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLarge net mass gain (\u0026thinsp;~\u0026thinsp;+\u0026thinsp;16%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eArgon prevents further oxidation during sintering, but residual oxygen can still occupy pores and become physically enclosed once particle necks close, counteracting densification. This trapped oxygen reacts with chromium to form a Cr₂O₃ oxide scale, increasing the part\u0026rsquo;s mass and locking oxide films at particle boundaries.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Microstructural Characterization\u003c/h2\u003e\u003cp\u003eIn order to investigate the microstructural result during sintering, including necking formation, pore morphology, and particle coalescence which are critical for understanding mechanical integrity and sintering efficiency, scanning electron microscopy (SEM) was performed on vacuum-sintered and argon-sintered specimen that had undergone prior solvent followed by thermal debinding. Micrographs were captured at 10,000\u0026times; magnification using an acceleration voltage of 15.0 kV and a working distance of 10.5 mm. Particle and pore dimensions were measured using the SEM calibration scale (1 cm\u0026thinsp;=\u0026thinsp;5 \u0026micro;m).\u003c/p\u003e\u003cp\u003eThe neck formation between particles exhibited a clear dependence on the sintering atmosphere. Vacuum-sintered specimens showed a neck growth ratio exceeding unity (1.06), indicating progression beyond initial particle contact to intermediate-stage sintering where neck enlargement promotes the development of continuous metallic pathways between adjacent particles, as evidenced in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(A), Observation 1. According to classical sintering theory (Mazlan et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), values\u0026thinsp;\u0026gt;\u0026thinsp;1.0 suggest that surface diffusion and grain boundary migration have progressed sufficiently to enable load-bearing connections. This reflects effective particle coalescence and densification facilitated by unhindered atomic diffusion. In contrast, argon-sintered specimens displayed a lower neck growth ratio (0.75), characteristic of arrested sintering at the initial contact stage. The reduced neck growth under argon is attributed to residual oxygen and oxide layers at particle interfaces, which hinder atomic transport, combined with internal gas pressure that opposes capillary-driven densification. Consequently, argon-sintered specimens exhibited higher porosity (44.35%) and lower densification (55.65%) compared to vacuum-sintered samples. This comparison highlights that vacuum provides an environment conducive to neck growth and intermediate-stage densification, whereas argon, although inert, can limit neck development due to oxide barriers and restricted atomic mobility.\u003c/p\u003e\u003cp\u003eIn terms of pore morphology, vacuum-sintered specimens exhibited the pores in exhibited a spherical morphology with an average diameter of 6.31 \u0026micro;m, indicative of surface energy minimization typical of advancing densification (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(A), Observation 2). Pore rounding occurs when sufficient atomic mobility exists to minimize surface curvature based on Young-Laplace equation \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\varDelta\\:P=2\\gamma\\:/r\\)\u003c/span\u003e\u003c/span\u003e, where \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\gamma\\:\\)\u003c/span\u003e\u003c/span\u003e is surface energy and r is pore radius (Şahin et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The calculated localized porosity of 25.6% corresponds to a densification level of 74.4%, confirming that partial sintering had occurred while significant residual porosity remained. During sintering, pores naturally tend to round to minimize surface energy. However, if atomic diffusion is limited, this rounding is hindered, and pores remain angular ((Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(A), Observation 3). Accordingly, argon-sintered specimens retained angular pore morphologies, indicating restricted atomic mobility and limited surface energy minimization. According to Herring's scaling law which describes the relationship between pore size and diffusion distances required for spheroidization; larger pores require longer diffusion paths to become rounded. Pore spheroidization requires diffusion distances proportional to pore size, but oxide films at particle interfaces impede the necessary mass transport (Pellegrini et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The larger, more interconnected pores suggest that densification was hindered and the sintering process terminated before pore isolation could occur (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(B)). The higher porosity (44.35%) and lower densification (55.65%) in argon-sintered specimens highlight the combined effects of oxide barrier formation and restricted atomic transport, which limit neck growth and overall densification.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAs summarized in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, vacuum-sintered specimens achieved superior bonding and densification compared to argon-sintered ones. Vacuum sintering promoted neck growth, pore rounding, and effective densification, while argon sintering was less effective due to restricted diffusion. Specifically, vacuum-sintered samples showed a higher neck growth ratio (1.06 vs. 0.75), smaller particle size (15.38 \u0026micro;m vs. 19.48 \u0026micro;m), and lower porosity (25.60% vs. 44.35%), leading to higher densification (74.40% vs. 55.65%). In addition, they contained smaller, rounded pores, whereas argon-sintered specimens retained irregular pores and weaker particle bonding.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of microstructural parameters for vacuum-sintered and argon-sintered 17-4PH stainless steel specimens.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eItem\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVacuum-sintered\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eArgon-sintered\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAverage neck length (\u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e16.250\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14.61\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAverage particle diameter (\u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15.375\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19.48\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNeck growth ratio\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.75\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAverage pore diameter (\u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e6.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal pore area (\u0026micro;m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e63.97\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAverage particle cross-sectional area (\u0026micro;m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e185.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCalculated porosity (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e25.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e44.35\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCorresponding densification (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e74.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e55.65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Energy-Dispersive X-ray Spectroscopy (EDX) analysis\u003c/h2\u003e\u003cp\u003eThe elemental composition of the near-surface region was verified by conducting EDX analysis on specimens sintered under both vacuum and argon conditions. The obtained results are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, and a detailed comparison is provided in Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe presence of the expected 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH alloying elements (Fe, Cr, and Nb) in vacuum-sintered specimen confirmed that the alloy identity was preserved after sintering under vacuum conditions. For the 17-4PH bulk composition is dominated by Fe (~\u0026thinsp;60\u0026ndash;70 wt%) together with Cr, Ni, Cu, and Nb as alloying elements. In contrast, the EDX measurement of the vacuum-sintered specimen revealed a significantly lower Fe content (12.44 wt%). This apparent discrepancy arises from the limitation of EDX as a near-surface analytical technique, with a typical penetration depth of only\u0026thinsp;~\u0026thinsp;1\u0026ndash;2 \u0026micro;m. In porous microstructures, the interaction volume of the electron beam is further reduced by the presence of pore walls and voids, causing the analysis to underrepresent the true matrix composition. Consequently, the deviation between the bulk composition and the EDX results does not indicate elemental depletion but rather reflects the influence of porosity and the shallow sampling depth of EDX (He et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). EDX analysis revealed a significantly higher carbon concentration on the surface (1.99wt%), indicating enrichment with carbon-based residues from the polymeric binder, in agreement with the findings from Tosto et al. (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The carbon content increased from 0.07 wt% before sintering to 27.89 wt% after sintering, highlighting that the binder was not completely removed during the process. Under vacuum conditions, rapid gas evolution can result in the entrapment of carbonaceous residues within closed pores, thereby preventing their complete elimination. This phenomenon has been reported in previous studies, which demonstrated that vacuum processing is prone to carbon retention in the microstructure (Singh et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The presence of residual carbon is particularly significant, as it may locally modify the alloy chemistry, deteriorate corrosion resistance, and the influence of the interlayer bonding strength which compromise the mechanical performance of the sintered component (Tosto et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The detected phosphorus content (2.06 wt%) is likely derived from binder additives and may represent a potential source of embrittlement, as phosphorus segregation to grain boundaries is known to reduce cohesive strength (Coulson, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). In contrast, the low oxygen content and the preservation of the chromium signal showed that oxidation was minimal, thereby validating the protective effect of the vacuum atmosphere during sintering.\u003c/p\u003e\u003cp\u003eFor the argon-sintered specimen, the high oxygen content and the absence of key alloying elements such as Cr and Nb indicate surface oxidation and incomplete sintering reactions. The substantial oxygen level (4.70 wt%) observed despite the nominally inert atmosphere showed that residual oxygen in the furnace system (estimated at \u0026lt;\u0026thinsp;0.1%) was sufficient to oxidize chromium at sintering temperatures. Thermodynamic calculations support this observation, as the formation of Cr₂O₃ has a Gibbs free energy of approximately \u0026minus;\u0026thinsp;540 kJ/mol at 1100\u0026deg;C, providing a strong driving force for oxidation even under low oxygen partial pressures (Zhu et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The absence of Cr, Nb, and Ni signals in the EDX spectra is therefore more plausibly attributed to masking by surface oxide layers rather than elemental depletion. Oxide scales with thicknesses of 2\u0026ndash;5 \u0026micro;m can effectively attenuate the signals from the underlying metallic phases, which is consistent with the low total mass return (23.28%) recorded (Hryha \u0026amp; Wendel, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The formation of such oxide barriers explains the arrested sintering behaviour and the deterioration of mechanical properties subsequently observed.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eEDX elemental composition of vacuum- and argon-sintered specimen\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eElement\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eVacuum-sintered\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003eArgon-sintered\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMass (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAtom (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNotes\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMass (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAtom (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNotes\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFe\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e37.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBase metal; signal likely affected by surface porosity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e14.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e37.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eBase metal; surface signal captured\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCr\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCorrosion-resistant element\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNot detected; below detection or oxidized\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNb\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eStrengthening alloying element\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNot detected; below detection or oxidized\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMay cause brittleness\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNot detected; below detection or oxidized\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIndicate residual carbon from binder\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e7.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eResidual binder presence\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePotential embrittlement risk\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e2.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e12.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eImpurity; possible embrittlement\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCu\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMinor contamination\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMinor contamination\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eExpected in 17-4PH but very low value here\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNot detected; below detection or oxidized\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e4.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e41.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIndicates surface oxidation\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTracing alloy element\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Mechanical characterization\u003c/h2\u003e\u003cp\u003eTensile and Charpy impact tests were conducted to evaluate the mechanical properties of FFF-printed 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel specimens sintered under two different atmospheres: argon and vacuum.\u003c/p\u003e\u003cdiv id=\"Sec16\" class=\"Section3\"\u003e\u003ch2\u003e3.5.1 Tensile test\u003c/h2\u003e\u003cp\u003eUsing Image J, the porosity of the vacuum-sintered specimen was determined to be 25.6%, corresponding to a real load-bearing area of 14.06 mm\u0026sup2;, slightly less than the measured 15 mm\u0026sup2;. Applying a correction factor of approximately 1.067, the adjusted tensile properties were 119.8 GPa for Young\u0026rsquo;s modulus, 43.3 MPa for yield strength, and 179.0 MPa for ultimate tensile strength. In comparison, the argon-sintered specimen exhibited a higher porosity of 44.35%, resulting in a real load-bearing area of 10.52 mm\u0026sup2;. With a correction factor of about 1.426, the corresponding tensile properties were 68.4 GPa, 2.17 MPa, and 5.53 MPa for Young\u0026rsquo;s modulus, yield strength, and ultimate tensile strength, respectively. Even after accounting for these corrections, the measured values remained substantially lower than those reported by Markforged, likely due to the presence of porosity acting as stress concentrators, which promoted premature failure (Tosto et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). FFF specimens exhibited a similar reduction in mechanical properties relative to injection-molded samples (Cicala et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Tosto et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Tronvoll et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2018\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eThe vacuum-sintered specimens exhibited yielding behaviour, with a yield strength of 40.6 MPa and measurable ductility (0.629% elongation), indicating the successful development of metallic bonding. This pattern is indicative of intermediate sintering, when particle interfaces achieve enough cohesion to enable partial plastic deformation before failing (Wu et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). The smooth progression of the stress\u0026ndash;strain curve further confirms a relatively uniform load distribution through the developed neck network. By contrast, the argon-sintered specimens failed prematurely in a brittle manner, showing negligible ductility (0.014% elongation). Their irregular and jagged stress\u0026ndash;strain profile indicates non-uniform load transfer and the progressive fracture of individual particle contacts, behaviour associated with oxide barrier formation that obstructs metallurgical bonding (Brytan, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The tensile strength of the vacuum-sintered specimens (167.86 MPa) represents approximately 15% of the tensile strength of wrought 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH stainless steel (~\u0026thinsp;1100 MPa) (Table\u0026nbsp;\u003cspan refid=\"Tab9\" class=\"InternalRef\"\u003e9\u003c/span\u003e), which is consistent with the expectations for early-stage sintering at sub-optimal temperatures. The significant impact in tensile response between vacuum and argon conditions underscores the critical influence of sintering atmosphere. Vacuum sintering facilitated bonding and densification, yielding improved tensile performance, whereas argon sintering promoted oxidation and incomplete binder removal, leading to severe embrittlement. The tensile properties, as derived from the stress\u0026ndash;strain curves shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, are compared, and a summary of the mechanical performance under both sintering conditions is presented in Table\u0026nbsp;\u003cspan refid=\"Tab10\" class=\"InternalRef\"\u003e10\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab9\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMaterial properties as indicated by the manufacturer\u0026rsquo;s data sheet of Markforged 17-4PH SS (Kedziora et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17-4PH (XY)\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYield strength (MPa)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUltimate tensile strength (MPa)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1050\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eModulus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e170\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElongation (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHardness\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e30 HRC\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003csup\u003e1\u003c/sup\u003e No values for the Z direction are given by the manufacturer. The data were extracted from the technical data sheet released by Desktop Metal with their Studio System\u0026trade;.\u003c/p\u003e\u003cp\u003eIn order to compare the results of this study with other works on 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH FFF specimens, Table\u0026nbsp;\u003cspan refid=\"Tab10\" class=\"InternalRef\"\u003e10\u003c/span\u003e summarizes the details, and the normalized data are presented in graphical form (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The normalization was performed by dividing the obtained values by the volume of the initial standard geometry, assuming a bar-shaped specimen defined by its length, width, and thickness. Vacuum sintering significantly enhances the normalized yield strength, achieving an improvement of approximately 25 times compared to argon-sintered specimens. However, the yield strength of vacuum-sintered parts remains lower than values reported in other FFF studies. Specimens sintered in argon exhibit minimal yield strength, likely due to poor densification and oxidation during processing. Abe et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) reported a normalized ultimate strength of 1.0 MPa, ~\u0026thinsp;11 times higher than the vacuum-sintered specimens in this work while other studies report values in the range of 0.1\u0026ndash;0.4 MPa. The excellence performance in Abe et al. is attributed to their custom fabrication of the binder system and optimized debinding and sintering procedures. Regarding normalized modulus, vacuum-sintered specimens in this study achieved\u0026thinsp;~\u0026thinsp;0.046 GPa, the highest among the compared studies. This indicates that vacuum sintering substantially improves stiffness and modulus relative to argon-sintered specimens and prior FFF work, suggesting enhanced particle bonding. While vacuum-sintered specimens exhibit limited ductility, their performance remains within the range reported in other studies.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab10\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 10\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOverview of tensile properties for 17\u0026thinsp;\u0026minus;\u0026thinsp;4 PH SS produced using FFF additive manufacturing\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"11\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFirst author\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAM type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBinder\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePowder (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eSpecimen dimension (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eDebinding\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSintering\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eYieldStr. (MPa)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eUltimate Tensile Str. (MPa)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eModulus (GPa)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eElongation (%)\u003c/p\u003e\u003cp\u003eStrain at break\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e(Zhang \u0026amp; Roch, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFFF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePTB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e64 (Purity\u0026nbsp;\u0026gt;\u0026nbsp;98% D50 28\u0026nbsp;\u0026micro;m)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eTensile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 100, W: 10, G: 32, H: 6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eSolvent: Acetone at 50\u0026deg;C for 5h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1360\u0026deg;C of 1h, quenched to RT under N\u003csub\u003e2\u003c/sub\u003e gas flow (30 l/ min)\u0026thinsp;+\u0026thinsp;annealed at 550\u0026deg;C for 4h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1007\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1212\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e175\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e5\u0026ndash;9.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e(Romero et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2025\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFFF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePTB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNot disclosed\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eTensile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 150, W: 20, H: 3\u003c/p\u003e\u003cp\u003e\u003cem\u003eCharpy\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 55, G: 27.5, H: 10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eSolvent debinding using Opteon\u0026trade; SF79 for 12\u0026ndash;13 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSinter-1 furnace under argon with 3% hydrogen to limit oxidation. Sintering occurred near 1100 ◦C over a 27-h cycle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e780\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1141\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e149\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e2.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e(Kedziora et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFFF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePTB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNot disclosed\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eTensile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 110, W:13, G: 38, H: 3\u003c/p\u003e\u003cp\u003e\u003cem\u003eCharpy\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 55, G: 27.5, H: 10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIn-house with the default parameters recommended by Markforged\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIn-house with the default parameters recommended by Markforged\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e441.0\u0026thinsp;\u0026plusmn;\u0026thinsp;55.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e495.9\u0026thinsp;\u0026plusmn;\u0026thinsp;77.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e142\u0026thinsp;\u0026plusmn;\u0026thinsp;65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e(Abe et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFFF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePOM, PP, PW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eTensile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 44.7, W:10.47, G: 24.7, H: 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eThermal: 600\u0026deg;C in N\u003csub\u003e2\u003c/sub\u003e gas for 2hr\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1280\u0026deg;C for 2 h (Ar gas)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e880\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e2.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e(Tosto et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFFF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePTB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNot disclosed\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eTensile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 100, W: 10, G: 32, H: 6\u003c/p\u003e\u003cp\u003eCharpy\u003c/p\u003e\u003cp\u003eL: 55, G: 27.5, H:10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIn-house with the default parameters recommended by Markforged\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eIn-house with the default parameters recommended by Markforged\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e443.00\u0026thinsp;\u0026plusmn;\u0026thinsp;6.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e497.40\u0026thinsp;\u0026plusmn;\u0026thinsp;9.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e108.00\u0026thinsp;\u0026plusmn;\u0026thinsp;6.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.79\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThis work\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFFF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePTB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eTensile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 63.5, W: 9.53, G: 6.53, H: 4\u003c/p\u003e\u003cp\u003eCharpy\u003c/p\u003e\u003cp\u003eL: 55, G: 27.5, H:10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eThermal or Solvent debinding\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1100\u0026deg;C for 3 h (Vacuum)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e40.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e167.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e112.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.629\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThis work\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFFF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePTB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eTensile\u003c/em\u003e\u003c/p\u003e\u003cp\u003eL: 63.5, W: 9.53, G: 6.53, H: 4\u003c/p\u003e\u003cp\u003eCharpy\u003c/p\u003e\u003cp\u003eL: 55, G: 27.5, H:10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eThermal or Solvent debinding\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1100\u0026deg;C for 3 h (Argon gas)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e3.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e0.014\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003ePTB\u0026thinsp;=\u0026thinsp;proprietary thermoplastic binder (unspecified composition), polyoxymethylene (POM), polypropylene (PP), and paraffin wax (PW).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section3\"\u003e\u003ch2\u003e3.5.2 Charpy impact test\u003c/h2\u003e\u003cp\u003eThe most unexpected finding in the Charpy impact test was that the vacuum-sintered specimen fractured catastrophically, completely fragmenting and failed to produce a measurable impact resistance; therefore, no results could be reported. Similarly, Kedziora et al. (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) reported no measurable values for FFF-printed specimens in their study. In contrast, the argon-sintered sample absorbed 0.7 J before fracturing. Although the absorbed energy was low, the specimen remained structurally intact, consistent with a brittle fracture influenced by porosity and surface oxidation. This paradoxical result highlights the difference between quasi-static and dynamic loading: while vacuum sintering improved tensile properties due to better densification, it also introduced processing-related defects. The presence of residual carbon from incomplete binder removal can lead to carbide precipitation or can react with chromium in 17-4PH, forming chromium carbides at grain boundaries. This local chromium depletion weakens grain boundaries, causing intergranular embrittlement. Vacuum sintering increased shrinkage and tensile properties under quasi-static load, however, toughness depends on defect tolerance. With pre-existing voids and carbon-induced embrittlement a microstructure prone to cleavage-type cracks, where cracks propagate rapidly along crystallographic planes. This made the specimen incapable of absorbing dynamic impact energy, leading to catastrophic fragmentation with no measurable toughness (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). Densification in argon-sintered specimens is slightly lower than in vacuum-sintered samples, resulting in reduced tensile strength. However, the residual porosity is more uniform and less severe, and internal stresses are lower due to gentler binder burnout. These factors allow the specimen to absorb energy during the Charpy impact test. Overall, the results indicate a trade-off between sintering atmospheres.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eThis study investigated 17-4PH stainless steel parts fabricated via FFF, focusing on the effects of different debinding methods (solvent and thermal) and sintering atmospheres (vacuum and argon). Thermal debinding alone was found unsuitable for this filament; a sequential approach combining solvent debinding with controlled thermal profiling is recommended. Vacuum sintering promoted effective densification, with 7\u0026ndash;13% linear shrinkage and 74.4% relative density, while argon-sintered specimens exhibited minimal shrinkage (~\u0026thinsp;1%) and lower relative density (55.65%). Vacuum sintering facilitated bonding and densification, yielding improved tensile performance, whereas argon sintering promoted oxidation and incomplete binder removal, leading to severe embrittlement. Vacuum sintering facilitated particle bonding and densification, achieving a porosity of 25.6% and resulting in enhanced tensile performance. However, toughness was limited due to pre-existing voids and carbon-induced embrittlement, which promoted cleavage-type crack propagation and catastrophic fragmentation under dynamic loading. In contrast, argon-sintered specimens exhibited higher porosity (44.35%), lower densification, and reduced tensile strength, but their more uniform residual porosity and lower internal stresses from gentler binder burnout allowed them to absorb energy during Charpy impact testing.\u003c/p\u003e\u003cp\u003eOverall, these results highlight a trade-off between sintering atmospheres: vacuum sintering maximizes strength and stiffness, whereas argon sintering improves energy absorption and reduces brittleness. This study provides critical guidance for selecting processing routes in FFF 17-4PH components to balance mechanical performance and structural integrity.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eDeclaration of Competing Interest\u003c/h2\u003e\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eThe author wrote the main manuscript text. Other co-author will be include later.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbe, Y., Kurose, T., Santos, M. V. A., Kanaya, Y., Ishigami, A., Tanaka, S., \u0026amp; Ito, H. (2021). 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(2025). Impact of oxygen content on debinding of binder jetted 17-4 PH stainless steel: Part II \u0026ndash; Sintering. \u003cem\u003ePowder Metallurgy\u003c/em\u003e,\u003cem\u003e 68\u003c/em\u003e(1), 16-28. https://doi.org/10.1177/00325899241307871 \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"fused filament fabrication, 17 − 4 PH stainless steel, debinding, sintering, mechanical propertie","lastPublishedDoi":"10.21203/rs.3.rs-7828599/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7828599/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFused filament fabrication (FFF) of 17-4PH stainless steel provides a cost-effective route for producing complex components, but the final properties strongly depend on debinding and sintering. Unsuitable conditions may cause incomplete binder removal, oxidation, and poor densification; thus, optimized debinding strategies and atmosphere selection are essential to balance strength, stiffness, and toughness. Existing studies on FFF 17-4PH limited, particularly regarding the comparative influence of debinding method, and sintering atmosphere. This study aimed to study solvent\u0026ndash;thermal debinding combined with sintering at ~\u0026thinsp;1100\u0026deg;C under argon and vacuum atmospheres. Characterization included dimensional and mass changes, microstructural evolution, and mechanical testing. Vacuum-sintered specimens exhibited 7\u0026ndash;13% linear shrinkage, 74.4% relative density, and 25.6% porosity, achieving superior tensile performance: 112 GPa Young\u0026rsquo;s modulus, 40.6 MPa yield strength, 167 MPa ultimate strength, and 0.629 strain at break. By contrast, argon-sintered specimens showed only\u0026thinsp;~\u0026thinsp;1% shrinkage, reduced density (55.7%), and higher porosity (44.3%), resulting in tensile properties nearly 25-fold lower. Load-bearing model predictions agreed with experiments with a correction factor of 1.426. Despite higher strength, vacuum-sintered specimens suffered toughness limitations due to voids and carbon-induced embrittlement, causing brittle fracture under impact. Conversely, argon-sintered specimens, though weaker, displayed more uniform porosity and reduced internal stresses, enabling better energy absorption during Charpy testing. These findings highlight a trade-off: thermal debinding alone is unsuitable for this filament, while combining solvent with controlled thermal profiling is recommended. Vacuum sintering improves strength and stiffness, whereas argon sintering enhances impact tolerance, emphasizing the importance of atmosphere selection.\u003c/p\u003e","manuscriptTitle":"Effect of Debinding Method and Sintering Atmosphere on Fused Filament Fabrication Printed 17-4PH Stainless Steel at Intermediate Sintering Temperatures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-05 11:46:45","doi":"10.21203/rs.3.rs-7828599/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"447ae437-808f-4268-b5bc-883ec58afc61","owner":[],"postedDate":"November 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-28T11:08:59+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-05 11:46:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7828599","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7828599","identity":"rs-7828599","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}