Investigation on Microstructure and Mechanical Properties of Hastelloy-X Thin Wall Specimens obtained by PBF-LB/M

Investigation on Microstructure and Mechanical Properties of Hastelloy-X Thin Wall Specimens obtained by PBF-LB/M | 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 Investigation on Microstructure and Mechanical Properties of Hastelloy-X Thin Wall Specimens obtained by PBF-LB/M Niccolò Baldi, Lokesh Chandrabalan, Giulio Carcasci, Alessandro Giorgetti, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5849361/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 Powder Bed Fusion—Laser Beam/Metal (PBF-LB/M) is considered one of the most versatile and promising among the Additive Manufacturing (AM) techniques, enabling the fabrication of dimensionally precise parts due to the lower thermo-mechanical distortions introduced in the process. Moreover, PBF-LB/M facilitates the manufacturability of several metal alloys, such as nickel-based ones, retaining acceptable structural integrity that can be improved with the aid of different post-process operations on the final part. These advantages and capabilities of the process allow the manufacturing of geometrically and dimensionally complex parts, such as thin walls and intricate structures. The aim of this work is to study the impacts on microstructure and mechanical properties based on tensile specimens’ thickness produced in Hastelloy-X alloy. The specimens were produced as per ASTM E8/E8M-24. The material microstructure is evaluated through a grain size and orientation and porosity percentage analysis using an optical microscope. The material mechanical properties are assessed through a tensile test at room temperature on dog bone specimens that were fabricated both parallel and perpendicular to the building direction. The results obtained in this work show a significant reduction in mechanical properties as a function of specimen thickness, resulting from a gradual decrease from the baseline to 40% of it. Specifically, there was a 16% decrease in the Ultimate Tensile Strength, a 23% reduction in the Young's Modulus, and a 41% decrease in the Elongation at Break. In addition, it has been observed that specimens’ printing orientation has an important influence on mechanical properties, regardless of the specimen thickness. An analysis of porosity, grain size, and orientation evaluates the microstructure of tested specimens, revealing significant differences between horizontal and vertical specimens. Additive Manufacturing PBF-LB/M Thin Wall Mechanical Properties Microstructure Nickel-based alloy Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Introduction Powder Bed Fusion - Laser Beam/Metal (PBF-LB/M) technology is an advanced additive manufacturing (AM) method that has become increasingly valuable in the energy sector due to its ability to produce high-precision and complex turbomachinery components. This technology facilitates the creation of intricate geometry, enhances material efficiency, and allows for rapid prototyping, accelerating the development of more efficient energy systems. By selectively melting metallic powder layer by layer using a high-powered laser, PBF-LB/M offers unparalleled design freedom, enabling the fabrication of parts with complex internal structures and optimized material properties that are difficult to achieve with traditional manufacturing processes [ 1 – 12 ]. In recent years, the enhancements and advancements in metal printing have promoted the proliferation of the PBF-LB/M technique across various industrial sectors such as aerospace, aviation, automotive energy, oil, gas, and medical fields. In particular, the capability of the PBF-LB/M process to manufacture parts with minimal weight while maintaining the mechanical and performance requirements of the component has facilitated the distribution of this AM technique in the aerospace industry [ 2 , 13 ]. Furthermore, the biomedical industry has benefited from the use of PBF-LB/M due to the ability to build highly complex lattice structures integrated with customized implants based on patient-specific anatomy [ 14 ]. On the other hand, PBF-LB/M technology plays a vital role in the production of critical parts such as turbine blades, which are exposed under a variety of operating conditions, including corrosive environments. For instance, the ability to manufacture integrated cooling channels in gas turbine parts without compromising their durability is possible due to the design freedom offered by PBF-LB/M technology. However, these advantages offered by AM are subject to material specifications. The widely used materials in PBF-LB/M technology are Ni-based superalloys due to their associated low thermal conductivity and reduced machining difficulties [ 15 – 17 ]. Despite the numerous advantages of PBF-LB/M technology, one significant technical challenge is producing thin-walled structures, which are crucial in turbomachinery parts to optimize heat transfer and associated fluid dynamic properties with reduced weight [ 18 ]. However, fabricating integrated thin wall structures through PBF-LB/M is complex due to several factors. Thermal distortion is one of the primary concerns. This is due to the high heat input from the laser, which generates thermal stresses that lead to localized warping or distortion of the structures during the building process [ 19 ]. Maintaining a stable powder bed is also crucial for the accuracy of the build, and thin walls can exacerbate issues with powder bed stability, resulting in defects or incomplete fusion [ 20 ]. Furthermore, the resolution of the laser and the size of the powder particles impose physical limitations on the minimum achievable wall thickness, requiring precise control over process parameters to ensure consistency and uniformity in thin walls [ 21 ]. Due to these technical difficulties in producing thin-wall structures, numerous studies aim to investigate how these difficulties affect the mechanical properties of the printed parts. Overcoming these challenges requires a deep understanding of the PBF-LB/M process, advanced simulation techniques, and continuous optimization of materials and parameters. Research and development efforts are focused on enhancing the accuracy and reliability of thin-walled structures, making PBF-LB/M a more viable solution for the energy sector and beyond. Addressing these challenges through ongoing research and innovation will unlock new possibilities for advanced manufacturing in energy applications, particularly in turbomachinery, paving the way for more efficient and resilient energy systems [ 22 ]. Vu et al. studied the correlation between the Ultimate Tensile Strength (UTS), Yield Strength and surface roughness by varying the wall thickness and the slope angle of 316L printed parts [ 23 ]. On the other hand, Zhang et al. [ 24 ] investigated the macro-mechanical behavior of PBF-LB/M parts, printed by AlSi10Mg, in correlation with relative densities. While Cai et al. further investigated the effect of process parameters on the mechanical properties for thin-wall parts, using Ti6Al4V material [ 25 ]. The aim of this paper is to investigate how the mechanical properties of PBF-LB/M-printed specimens change as their thickness decreases. Understanding the relationship between wall thickness and mechanical performance is critical for optimizing the design and manufacturing of thin-walled structures. By systematically varying the wall thickness and evaluating the resulting mechanical properties, this study seeks to provide insights into the limitations and capabilities of PBF-LB/M technology for producing reliable and high-performance components with integrated thin wall structures. The experimental campaign uses Hastelloy-X, a widely used nickel-based superalloy in the AM field, for all specimens. The mechanical properties are evaluated through tensile tests at room temperature on heat-treated and unmachined specimens, including horizontal and vertical building directions. The structure of the paper is organized as follows: in Section 2, the experimental details are fully described and provided. Section 3 provides an explanation of the tensile test results, and the microstructure analyses conducted on the tensile-tested specimens. Finally, Section 4 presents the conclusion and proposes developments for further investigations. Material and Methods As mentioned in the previous section, all the specimens manufactured and analyzed in this experimental campaign are made of Hastelloy-X alloy. Table 1 reports the chemical composition, mechanical and physical properties of Hastelloy-X [ 26 ]. Table 1 Chemical Composition of Hastelloy-X alloy. Element % Weight Al 0.04 B < 0.01 Co 1.77 C 21.70 Cu < 0.01 Fe 19.1 Mn < 0.01 Mo 8.50 Ni Bal P 0.01 Se < 0.005 Si 0.1 W 0.77 An EOS Eosint M-400 machine, with a single ytterbium fiber laser, was used to create tensile samples. The laser had a wavelength of 1070 nm, a minimum spot size of 80 µm, and a maximum power of 1 KW for all tests. The case study utilizes a C40 steel building platform with the following dimensions: 400x400x40mm (thickness). An argon gas flow was continuously pumped inside the building chamber to maintain oxygen content under 100 ppm. The temperature of the building platform was kept constant throughout building process at 80°C. We printed all the tested specimens using the process parameters set, widely developed and tested in previous literature studies for the Hastelloy-X alloy [ 26 ], as listed in Table 2 . Table 2 Process parameters used to manufacture all specimens Laser Power (W) 270 Scanning Speed (mm/s) 1000 Hatch Distance (mm) 0.09 Customized dog-bone-shaped specimens were designed in accordance with ASTM E8/E8M (Rectangular Tension Test Specimens—Subsize Specimen) as illustrated in Fig. 1 . We produced specimens with different wall thicknesses to investigate the mechanical properties as a function of wall thickness. For confidentiality purposes, the specimen wall thickness variation is disclosed in terms of percentage from baseline values, where baseline is indicated as 100% and the least wall thickness is indicated as 40%. The tensile tests were conducted on the fabricated specimens as per the guidelines and specifications provided in ASTM E8/E8M 13a. The standard suggests that the thickness of the specimen must be less than 16 mm, which is in line with this experimental work. The dimensions of the specimens have been scaled in such a manner that the proportions among the ASTM E8/E8M guidelines and the fabricated specimens are kept constant. Additionally, we fabricated tensile specimens in both horizontal and vertical orientations to assess the impact of build orientation on the mechanical properties of the material. In order to obtain statistically significant experimental data, three tensile specimens of the same type were fabricated for every wall thickness and printing orientation; thus, a total of 18 specimens were produced, as reported in Table 3 . The specimens’ thickness varied from the baseline, indicated as 100% of thickness, to 40% of it, including a middle level of 70%. Figure 2 illustrates the building layout and positioning of the specimens on the building platform. Table 3 Specimens tracking table, reporting number, thickness and building direction. Specimen # Thickness (%) Building Direction 1 100 Horizontal 2 100 Horizontal 3 100 Horizontal 4 100 Vertical 5 100 Vertical 6 100 Vertical 7 70 Horizontal 8 70 Horizontal 9 70 Horizontal 10 70 Vertical 11 70 Vertical 12 70 Vertical 13 40 Horizontal 14 40 Horizontal 15 40 Horizontal 16 40 Vertical 17 40 Vertical 18 40 Vertical Upon completion of the specimen production, Wire Electrical Discharge Machining (EDM) was employed to detach the specimens from the building platform. The cut is executed by moving the wire in close proximity to the building platform. After the removal from the building platform, all the specimens are solution heat treated in a vacuum furnace [ 26 ]. After heat treatment and before mechanical testing, we measure the specimen dimensions using a vernier caliper. Microstructural analysis, porosity, and grain size are carried on broken specimens to evaluate the density of tested specimens and grain dimension and orientation. To evaluate the grain size, the specimens are etched with oxalic acid to highlight the grains’ boundaries. Results and Discussion The particle size distribution (PSD) of powder is close to the nominal specification of 15/63 microns; in fact, 95.4% in volume of powder is within this range, as shown in Fig. 3 . We measure the particle size dimension using a laser diffractometry method. The specimens have been correctly printed using the machine and the process parameters mentioned in Section 2, and no anomalies have been detected during the printing process. After heat treatment, the measured thickness values showed no significant variations. An extract of the raw plot, from machine tensile software, for the achieved mechanical properties is shown in Fig. 5 . Figure 6 depicts the Individual Plots corresponding to the results for Yield Strength, UTS, Elongation at Break and Young Modulus. From Fig. 6 , it is observed that the Building Direction and Thickness of Specimen do not impact the material Yield Strength. On the other hand, a clear trend is noted and identified between the build direction and UTS and Elongation at Break. It should be noted that the UTS values decrease drastically with the reduction in wall thickness irrespective of the building orientation, i.e., horizontal and vertical specimens. However, the same trend is observed as a function of specimens’ thickness for the Elongation at Break. On the contrary, Young Modulus is significantly reduced as a function of reduction in specimen thickness and dispersion in the measured data. In order to determine the most influential factor among the Specimen thickness and building direction as a function of the tested mechanical properties, mean effects analysis was performed. The results of the Mean Effects Analysis are illustrated in Fig. 7 . Figure 7 (A) shows that the Building Direction and Specimen Thickness have a small impact on Yield Strength (Y S ). The highest Y S measured is 290 MPa, and the lowest is 273 MPa, leading to a small difference of just 6%. We calculate this variation by averaging all the Y S measurements. On the other hand, a strong effect between UTS, and both Building Direction and Specimens’ Thickness is observed with a variation of 16.5% between the minimum and maximum measured value. On the other hand, a significant effect is observed of specimen thickness in terms of Elongation at Break, especially at thickness level below 70% from the baseline, while the Building Direction has a lower effect on this property. However, a significant deterioration for Young Modulus is noted for Specimens’ Thickness lower than 70% from baseline. From the Interaction Plots depicted in Fig. 8 , no interactions are highlighted between Yield Strength, UTS and Elongation at Break, while a weak interaction can be observed for Young Modulus at 40% of Specimens’ Thickness from baseline. In order to investigate the variations in mechanical properties based on the build orientation of the specimens, microstructural analyses were performed on both vertically and horizontally built tested tensile specimens. The tensile-tested specimens are cautiously cut along the building direction, i.e., along the Z axis for vertical specimens and along the X-Y plane for horizontal ones. The specimens are well polished after being embedded in conductive resin to guarantee the effectiveness of the porosity analysis. The porosity analysis is carried out through an optical microscope (OM). Six fields are acquired for each with a magnification factor of 100x. The porosity percentage is then evaluated by processing the acquired images using the commercial tool ImageJ. The measured porosity percentage for each specimen is listed in Table 4 . Table 4 – Porosity analysis tracking table. Specimen # Porosity average (%) 1 0.053 2 0.043 3 0.027 4 0.031 5 0.041 6 0.024 7 0.044 8 0.019 9 0.032 10 0.023 11 0.017 12 0.042 13 0.026 14 0.031 15 0.022 16 0.033 17 0.037 18 0.034 Based on the results listed in Table 4 , the porosity value measured for each analyzed specimen is low and the material could be considered fully dense as shown in Fig. 9 . Moreover, to obtain further information about the material’s microstructure, grain orientation, and size, each specimen is etched with electrolytic oxalic acid to highlight the grain’s boundary. Figures 10 and 11 illustrate the grain size and orientation of the corresponding material for horizontal and vertical specimens, respectively. From the microstructure analysis as shown in Figs. 10 and 11 , significant differences in terms of grain size and orientation between the horizontal and vertical specimens are noted. In terms of microstructure, as illustrated in Fig. 10 , the partial recrystallization of material can be observed, and the grains are found to be elongated in the building direction of specimens, resulting in a similar condition to that of an as-built material condition. This phenomenon offers a comprehensive explanation for the higher UTS and lower Elongation at Break observed in the horizontal specimens, which can be attributed to the presence of unidirectionally elongated grains. The lack of complete recrystallization of the material is due to the lower residual stress inducted by the PBF-LB/M process on the material due to the lower thermal gradient on these specimens, which is in line as stated in [ 26 ]. Another explanation for the reduction in residual stresses in horizontal specimens is attributed to the effect of the EDM cut applied across the entire bottom surface of the specimen. On the other hand, the microstructure analysis of vertically built specimens shown in Fig. 11 appears fully recrystallized, and the grains have completely lost the effect of directionality along the building direction. In addition, the grains are coarser with respect to the horizontally built specimens, as illustrated in Fig. 10 . This phenomenon of partial and complete recrystallization of the material based on the building orientations adequately explains the lower UTS and higher Elongation at Break for vertical specimens, resulting in a ductile material. Further EBSD analysis on the material in its as-built condition is required to quantify the aspect of residual stress formation in the material. Conclusions The study's results indicate that specimen thickness significantly influences the degradation of mechanical properties. Furthermore, it is evident that both vertical and horizontal specimens with a thickness of 40% from the baseline exhibit lower mechanical properties than those with a thickness of 70% from the baseline itself. As a result, it can be stated that specimens in the range of 40% of wall thickness from the baseline are found to be critical in terms of mechanical properties, thus containing the building of thin wall parts in PBF-LB/M. However, the partial recrystallization for horizontal specimens can be addressed by marginally increasing the temperature of the solution heat treatment. Furthermore, it is important to perform tensile tests at higher temperatures to confirm the hypothesis of the grain directionality with respect to material recrystallization. In addition, the residual stresses in the as-built condition for both horizontal and vertical specimens need to be investigated to underline the material characteristics with respect to the printing process. Declarations Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Competing Interests The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Niccolo Baldi, Giulio Carcasci, Lokesh Chandrabalan and Marco Manetti reports a relationship with Baker Hughes - Nuovo Pignone that includes: employment. The other 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 Contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Niccolo Baldi, Lokesh Chandrabalan and Alessandro Giorgetti. The first draft of the manuscript was written by Niccolo Baldi, Lokesh Chandrabalan and Alessandro Giorgetti and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. References Murr LE (2018) Strategies for creating living, additively manufactured, open-cellular metal and alloy implants by promoting osseointegration, osteoinduction and vascularization: An overview. Journal of Material Science and Technology 35:231–241 doi:10.1016/j.jmst.2018.09.003. Blakey-Milner B, Gradl P, Snedden G, Brooks M, Pitot J, Lopez E, Leary M, Berto F, Du Plessis A (2021) Metal additive manufacturing in aerospace: A review. Materials & Design 209:110008. doi:10.1016/j.matdes.2021.110008. 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Arcidiacono","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Gabriele","middleName":"","lastName":"Arcidiacono","suffix":""},{"id":431182739,"identity":"69df989a-4e8f-4c23-9c23-f040d3776af8","order_by":5,"name":"Paolo Citti","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Paolo","middleName":"","lastName":"Citti","suffix":""},{"id":431182740,"identity":"1d138dfe-45ee-4962-a6b5-d5265e490cbe","order_by":6,"name":"Marco Manetti","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Marco","middleName":"","lastName":"Manetti","suffix":""}],"badges":[],"createdAt":"2025-01-17 13:06:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5849361/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5849361/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":79442661,"identity":"c39f3151-ed58-4e87-9258-f8ac75be99c4","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":52189,"visible":true,"origin":"","legend":"\u003cp\u003eOverview of Specimen's dimensions in mm\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/eae02f44874f666c70dedbfb.png"},{"id":79443464,"identity":"e0ad9d0d-68c9-4f5e-b5ce-47f67bb7dbd1","added_by":"auto","created_at":"2025-03-28 13:26:53","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":209295,"visible":true,"origin":"","legend":"\u003cp\u003eJob Layout\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/4accfb93518cbf0dfe719902.png"},{"id":79443466,"identity":"eb3a517c-3b27-4172-9704-926864644033","added_by":"auto","created_at":"2025-03-28 13:26:53","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":80988,"visible":true,"origin":"","legend":"\u003cp\u003eParticle size distribution.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/8296addfa4e61f294ede2b8b.png"},{"id":79442666,"identity":"bd6ddb3a-86e6-4af6-8b87-493d763d9752","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":243816,"visible":true,"origin":"","legend":"\u003cp\u003ePrinted specimens before performing mechanical tests\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/928dca5ed1b7efa69853a9ac.png"},{"id":79442664,"identity":"b8645a3f-1772-412f-b845-74fcbdd1fc32","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":90957,"visible":true,"origin":"","legend":"\u003cp\u003eRaw plot of mechanical properties extracted from the tensile machine software\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/fb2b7b651e83d58ba5654197.png"},{"id":79442669,"identity":"f371577e-9de3-41df-8ada-526cc7f143a2","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":91098,"visible":true,"origin":"","legend":"\u003cp\u003eIndividual Plot respectively for Yield Strength ( A), UTS ( B), Elongation at Break ( C) and Young Modulus ( D).\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/b324fd603d06893ac35412c9.png"},{"id":79443468,"identity":"8cb06d79-ff79-4e0a-852a-20a2285b8016","added_by":"auto","created_at":"2025-03-28 13:26:53","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":95186,"visible":true,"origin":"","legend":"\u003cp\u003eMain Effect Plots overview, respectively for Yield Strength ( A), Ultimate Tensile Test (UTS) ( B), Elongation at Break ( C) and Young Modulus ( D).\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/2285df405157c03f4088772c.png"},{"id":79442672,"identity":"9daaa409-623a-406c-bcd4-88db75338a6e","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":75420,"visible":true,"origin":"","legend":"\u003cp\u003eInteraction Plots overview, respectively for Yield Strength ( A), UTS ( B), Elongation at Break ( C) and Young Modulus ( D).\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/fb73added053947ac91b2d07.png"},{"id":79442676,"identity":"609df3f1-6a96-477a-a4a4-34e3c9708503","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":54138,"visible":true,"origin":"","legend":"\u003cp\u003eMaterial's microstructure images acquired at Optical Microscope (OM), respectively for specimen #1 (on the left side) and #10 (on the right side). Evaluating these pictures results evident the fully dense condition of material.\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/598ea28eba07f8175217dbcb.png"},{"id":79442680,"identity":"bcb5f7c0-3088-4d01-8646-fca6bc8c2089","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":242533,"visible":true,"origin":"","legend":"\u003cp\u003eGrain analysis, in terms of orientation, for horizontal specimens\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/59e3c035e4ffc7383d50b279.png"},{"id":79442689,"identity":"a6418e71-1abf-4165-ac56-2f0fbb3966ed","added_by":"auto","created_at":"2025-03-28 13:18:53","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":135621,"visible":true,"origin":"","legend":"\u003cp\u003eGrain analysis, in terms of orientation, for vertical specimens.\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/0e35bce47ba3314b40b0f73b.png"},{"id":80562345,"identity":"26921713-9528-4d8d-9cda-ac7c68fba1f3","added_by":"auto","created_at":"2025-04-14 16:47:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1911354,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5849361/v1/46177dab-e9c5-4cc7-979c-e107616df5e9.pdf"}],"financialInterests":"","formattedTitle":"Investigation on Microstructure and Mechanical Properties of Hastelloy-X Thin Wall Specimens obtained by PBF-LB/M","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePowder Bed Fusion - Laser Beam/Metal (PBF-LB/M) technology is an advanced additive manufacturing (AM) method that has become increasingly valuable in the energy sector due to its ability to produce high-precision and complex turbomachinery components. This technology facilitates the creation of intricate geometry, enhances material efficiency, and allows for rapid prototyping, accelerating the development of more efficient energy systems. By selectively melting metallic powder layer by layer using a high-powered laser, PBF-LB/M offers unparalleled design freedom, enabling the fabrication of parts with complex internal structures and optimized material properties that are difficult to achieve with traditional manufacturing processes [\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5 CR6 CR7 CR8 CR9 CR10 CR11\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn recent years, the enhancements and advancements in metal printing have promoted the proliferation of the PBF-LB/M technique across various industrial sectors such as aerospace, aviation, automotive energy, oil, gas, and medical fields. In particular, the capability of the PBF-LB/M process to manufacture parts with minimal weight while maintaining the mechanical and performance requirements of the component has facilitated the distribution of this AM technique in the aerospace industry [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Furthermore, the biomedical industry has benefited from the use of PBF-LB/M due to the ability to build highly complex lattice structures integrated with customized implants based on patient-specific anatomy [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. On the other hand, PBF-LB/M technology plays a vital role in the production of critical parts such as turbine blades, which are exposed under a variety of operating conditions, including corrosive environments. For instance, the ability to manufacture integrated cooling channels in gas turbine parts without compromising their durability is possible due to the design freedom offered by PBF-LB/M technology. However, these advantages offered by AM are subject to material specifications. The widely used materials in PBF-LB/M technology are Ni-based superalloys due to their associated low thermal conductivity and reduced machining difficulties [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the numerous advantages of PBF-LB/M technology, one significant technical challenge is producing thin-walled structures, which are crucial in turbomachinery parts to optimize heat transfer and associated fluid dynamic properties with reduced weight [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. However, fabricating integrated thin wall structures through PBF-LB/M is complex due to several factors. Thermal distortion is one of the primary concerns. This is due to the high heat input from the laser, which generates thermal stresses that lead to localized warping or distortion of the structures during the building process [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Maintaining a stable powder bed is also crucial for the accuracy of the build, and thin walls can exacerbate issues with powder bed stability, resulting in defects or incomplete fusion [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Furthermore, the resolution of the laser and the size of the powder particles impose physical limitations on the minimum achievable wall thickness, requiring precise control over process parameters to ensure consistency and uniformity in thin walls [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDue to these technical difficulties in producing thin-wall structures, numerous studies aim to investigate how these difficulties affect the mechanical properties of the printed parts. Overcoming these challenges requires a deep understanding of the PBF-LB/M process, advanced simulation techniques, and continuous optimization of materials and parameters. Research and development efforts are focused on enhancing the accuracy and reliability of thin-walled structures, making PBF-LB/M a more viable solution for the energy sector and beyond. Addressing these challenges through ongoing research and innovation will unlock new possibilities for advanced manufacturing in energy applications, particularly in turbomachinery, paving the way for more efficient and resilient energy systems [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Vu et al. studied the correlation between the Ultimate Tensile Strength (UTS), Yield Strength and surface roughness by varying the wall thickness and the slope angle of 316L printed parts [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. On the other hand, Zhang et al. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] investigated the macro-mechanical behavior of PBF-LB/M parts, printed by AlSi10Mg, in correlation with relative densities. While Cai et al. further investigated the effect of process parameters on the mechanical properties for thin-wall parts, using Ti6Al4V material [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe aim of this paper is to investigate how the mechanical properties of PBF-LB/M-printed specimens change as their thickness decreases. Understanding the relationship between wall thickness and mechanical performance is critical for optimizing the design and manufacturing of thin-walled structures. By systematically varying the wall thickness and evaluating the resulting mechanical properties, this study seeks to provide insights into the limitations and capabilities of PBF-LB/M technology for producing reliable and high-performance components with integrated thin wall structures. The experimental campaign uses Hastelloy-X, a widely used nickel-based superalloy in the AM field, for all specimens. The mechanical properties are evaluated through tensile tests at room temperature on heat-treated and unmachined specimens, including horizontal and vertical building directions.\u003c/p\u003e \u003cp\u003eThe structure of the paper is organized as follows: in Section 2, the experimental details are fully described and provided. Section 3 provides an explanation of the tensile test results, and the microstructure analyses conducted on the tensile-tested specimens. Finally, Section 4 presents the conclusion and proposes developments for further investigations.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cp\u003eAs mentioned in the previous section, all the specimens manufactured and analyzed in this experimental campaign are made of Hastelloy-X alloy. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e reports the chemical composition, mechanical and physical properties of Hastelloy-X [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\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 Hastelloy-X alloy.\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\u003eElement\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Weight\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAl\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eB\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCo\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.77\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCu\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFe\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMn\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMo\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSe\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.005\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSi\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eW\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.77\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\u003eAn EOS Eosint M-400 machine, with a single ytterbium fiber laser, was used to create tensile samples. The laser had a wavelength of 1070 nm, a minimum spot size of 80 \u0026micro;m, and a maximum power of 1 KW for all tests. The case study utilizes a C40 steel building platform with the following dimensions: 400x400x40mm (thickness). An argon gas flow was continuously pumped inside the building chamber to maintain oxygen content under 100 ppm. The temperature of the building platform was kept constant throughout building process at 80\u0026deg;C.\u003c/p\u003e \u003cp\u003eWe printed all the tested specimens using the process parameters set, widely developed and tested in previous literature studies for the Hastelloy-X alloy [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], as listed 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=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eProcess parameters used to manufacture all specimens\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\u003eLaser Power (W)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e270\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eScanning Speed (mm/s)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHatch Distance (mm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.09\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\u003eCustomized dog-bone-shaped specimens were designed in accordance with ASTM E8/E8M (Rectangular Tension Test Specimens\u0026mdash;Subsize Specimen) as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. We produced specimens with different wall thicknesses to investigate the mechanical properties as a function of wall thickness. For confidentiality purposes, the specimen wall thickness variation is disclosed in terms of percentage from baseline values, where baseline is indicated as 100% and the least wall thickness is indicated as 40%. The tensile tests were conducted on the fabricated specimens as per the guidelines and specifications provided in ASTM E8/E8M 13a. The standard suggests that the thickness of the specimen must be less than 16 mm, which is in line with this experimental work. The dimensions of the specimens have been scaled in such a manner that the proportions among the ASTM E8/E8M guidelines and the fabricated specimens are kept constant.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAdditionally, we fabricated tensile specimens in both horizontal and vertical orientations to assess the impact of build orientation on the mechanical properties of the material. In order to obtain statistically significant experimental data, three tensile specimens of the same type were fabricated for every wall thickness and printing orientation; thus, a total of 18 specimens were produced, as reported in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The specimens\u0026rsquo; thickness varied from the baseline, indicated as 100% of thickness, to 40% of it, including a middle level of 70%. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e illustrates the building layout and positioning of the specimens on the building platform.\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\u003eSpecimens tracking table, reporting number, thickness and building direction.\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\u003eSpecimen #\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThickness (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBuilding Direction\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHorizontal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eVertical\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\u003eUpon completion of the specimen production, Wire Electrical Discharge Machining (EDM) was employed to detach the specimens from the building platform. The cut is executed by moving the wire in close proximity to the building platform. After the removal from the building platform, all the specimens are solution heat treated in a vacuum furnace [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. After heat treatment and before mechanical testing, we measure the specimen dimensions using a vernier caliper. Microstructural analysis, porosity, and grain size are carried on broken specimens to evaluate the density of tested specimens and grain dimension and orientation. To evaluate the grain size, the specimens are etched with oxalic acid to highlight the grains\u0026rsquo; boundaries.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eThe particle size distribution (PSD) of powder is close to the nominal specification of 15/63 microns; in fact, 95.4% in volume of powder is within this range, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. We measure the particle size dimension using a laser diffractometry method.\u003c/p\u003e \u003cp\u003eThe specimens have been correctly printed using the machine and the process parameters mentioned in Section 2, and no anomalies have been detected during the printing process. After heat treatment, the measured thickness values showed no significant variations.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAn extract of the raw plot, from machine tensile software, for the achieved mechanical properties is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e depicts the Individual Plots corresponding to the results for Yield Strength, UTS, Elongation at Break and Young Modulus.\u003c/p\u003e \u003cp\u003eFrom Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, it is observed that the Building Direction and Thickness of Specimen do not impact the material Yield Strength. On the other hand, a clear trend is noted and identified between the build direction and UTS and Elongation at Break. It should be noted that the UTS values decrease drastically with the reduction in wall thickness irrespective of the building orientation, i.e., horizontal and vertical specimens. However, the same trend is observed as a function of specimens\u0026rsquo; thickness for the Elongation at Break. On the contrary, Young Modulus is significantly reduced as a function of reduction in specimen thickness and dispersion in the measured data.\u003c/p\u003e \u003cp\u003eIn order to determine the most influential factor among the Specimen thickness and building direction as a function of the tested mechanical properties, mean effects analysis was performed. The results of the Mean Effects Analysis are illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e (A) shows that the Building Direction and Specimen Thickness have a small impact on Yield Strength (Y\u003csub\u003eS\u003c/sub\u003e). The highest Y\u003csub\u003eS\u003c/sub\u003e measured is 290 MPa, and the lowest is 273 MPa, leading to a small difference of just 6%. We calculate this variation by averaging all the Y\u003csub\u003eS\u003c/sub\u003e measurements. On the other hand, a strong effect between UTS, and both Building Direction and Specimens\u0026rsquo; Thickness is observed with a variation of 16.5% between the minimum and maximum measured value. On the other hand, a significant effect is observed of specimen thickness in terms of Elongation at Break, especially at thickness level below 70% from the baseline, while the Building Direction has a lower effect on this property. However, a significant deterioration for Young Modulus is noted for Specimens\u0026rsquo; Thickness lower than 70% from baseline.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFrom the Interaction Plots depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, no interactions are highlighted between Yield Strength, UTS and Elongation at Break, while a weak interaction can be observed for Young Modulus at 40% of Specimens\u0026rsquo; Thickness from baseline.\u003c/p\u003e \u003cp\u003eIn order to investigate the variations in mechanical properties based on the build orientation of the specimens, microstructural analyses were performed on both vertically and horizontally built tested tensile specimens.\u003c/p\u003e \u003cp\u003eThe tensile-tested specimens are cautiously cut along the building direction, i.e., along the Z axis for vertical specimens and along the X-Y plane for horizontal ones. The specimens are well polished after being embedded in conductive resin to guarantee the effectiveness of the porosity analysis. The porosity analysis is carried out through an optical microscope (OM). Six fields are acquired for each with a magnification factor of 100x. The porosity percentage is then evaluated by processing the acquired images using the commercial tool ImageJ. The measured porosity percentage for each specimen is listed in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\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\u003e\u0026ndash; Porosity analysis tracking table.\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=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\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\u003ePorosity average (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.053\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.043\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.027\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.031\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.024\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.044\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.032\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.023\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.042\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.026\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.031\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.022\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.037\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.034\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\u003eBased on the results listed in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the porosity value measured for each analyzed specimen is low and the material could be considered fully dense as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMoreover, to obtain further information about the material\u0026rsquo;s microstructure, grain orientation, and size, each specimen is etched with electrolytic oxalic acid to highlight the grain\u0026rsquo;s boundary.\u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e and \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e illustrate the grain size and orientation of the corresponding material for horizontal and vertical specimens, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFrom the microstructure analysis as shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e and \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, significant differences in terms of grain size and orientation between the horizontal and vertical specimens are noted. In terms of microstructure, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, the partial recrystallization of material can be observed, and the grains are found to be elongated in the building direction of specimens, resulting in a similar condition to that of an as-built material condition. This phenomenon offers a comprehensive explanation for the higher UTS and lower Elongation at Break observed in the horizontal specimens, which can be attributed to the presence of unidirectionally elongated grains. The lack of complete recrystallization of the material is due to the lower residual stress inducted by the PBF-LB/M process on the material due to the lower thermal gradient on these specimens, which is in line as stated in [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Another explanation for the reduction in residual stresses in horizontal specimens is attributed to the effect of the EDM cut applied across the entire bottom surface of the specimen.\u003c/p\u003e \u003cp\u003eOn the other hand, the microstructure analysis of vertically built specimens shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e appears fully recrystallized, and the grains have completely lost the effect of directionality along the building direction. In addition, the grains are coarser with respect to the horizontally built specimens, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e. This phenomenon of partial and complete recrystallization of the material based on the building orientations adequately explains the lower UTS and higher Elongation at Break for vertical specimens, resulting in a ductile material.\u003c/p\u003e \u003cp\u003eFurther EBSD analysis on the material in its as-built condition is required to quantify the aspect of residual stress formation in the material.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe study's results indicate that specimen thickness significantly influences the degradation of mechanical properties. Furthermore, it is evident that both vertical and horizontal specimens with a thickness of 40% from the baseline exhibit lower mechanical properties than those with a thickness of 70% from the baseline itself. As a result, it can be stated that specimens in the range of 40% of wall thickness from the baseline are found to be critical in terms of mechanical properties, thus containing the building of thin wall parts in PBF-LB/M. However, the partial recrystallization for horizontal specimens can be addressed by marginally increasing the temperature of the solution heat treatment. Furthermore, it is important to perform tensile tests at higher temperatures to confirm the hypothesis of the grain directionality with respect to material recrystallization. In addition, the residual stresses in the as-built condition for both horizontal and vertical specimens need to be investigated to underline the material characteristics with respect to the printing process.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cu\u003eFunding\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eCompeting Interests\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare the following financial interests/personal relationships which may be considered as potential competing interests:\u003c/p\u003e\n\u003cp\u003eNiccolo Baldi, Giulio Carcasci, Lokesh Chandrabalan and Marco Manetti reports a relationship with Baker Hughes - Nuovo Pignone that includes: employment. The other 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\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eAuthor Contributions\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Niccolo Baldi, Lokesh Chandrabalan and Alessandro Giorgetti. The first draft of the manuscript was written by Niccolo Baldi, Lokesh Chandrabalan and Alessandro Giorgetti and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eMurr LE (2018) Strategies for creating living, additively manufactured, open-cellular metal and alloy implants by promoting osseointegration, osteoinduction and vascularization: An overview. Journal of Material Science and Technology 35:231\u0026ndash;241 doi:10.1016/j.jmst.2018.09.003.\u003c/li\u003e\n\u003cli\u003eBlakey-Milner B, Gradl P, Snedden G, Brooks M, Pitot J, Lopez E, Leary M, Berto F, Du Plessis A (2021) Metal additive manufacturing in aerospace: A review. Materials \u0026amp; Design 209:110008. doi:10.1016/j.matdes.2021.110008.\u003c/li\u003e\n\u003cli\u003eWang P, Song J, Nai MLS, Wei J (2020) Experimental analysis of additively manufactured component and design guidelines for lightweight structures: A case study using electron beam melting. 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CIRP Annals 65:737\u0026ndash;760. https://doi.org/10.1016/j.cirp.2016.05.004\u003c/li\u003e\n\u003cli\u003eVu HM, Meiniger S, Ringel B, Hoche HC, Oechsner M, Weigold M, Schmitt M, Schlick G (2022) Investigation of Material Properties of Wall Structures from Stainless Steel 316L Manufactured by Laser Powder Bed Fusion. Metals 12:285. https://doi.org/10.3390/met12020285\u003c/li\u003e\n\u003cli\u003eZhang Y, Majeed A, Muzamil M, Lv J, Peng T, Patel V (2021) Investigation for macro mechanical behavior explicitly for thin-walled parts of AlSi10Mg alloy using selective laser melting technique. Journal of Manufacturing Processes 66:269\u0026ndash;280. https://doi.org/10.1016/j.jmapro.2021.04.022\u003c/li\u003e\n\u003cli\u003eCai G, Liu H, Peng K, Wang B, Hu B (2024) Orthogonal experimental method to investigate the effect of process parameters on the mechanical properties of thin-walled parts by PBF-LB/M. Scientific Reports. https://doi.org/10.1038/s41598-024-70883-9\u003c/li\u003e\n\u003cli\u003eDeirmina F, Adegoke O, Del Col M, Pellizzari M (2023) Effect of layer thickness, and laser energy density on the recrystallization behavior of additively manufactured Hastelloy X by laser powder bed fusion. Additive Manufacturing Letters 7:100182. https://doi.org/10.1016/j.addlet.2023.100182\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":"Additive Manufacturing, PBF-LB/M, Thin Wall, Mechanical Properties, Microstructure, Nickel-based alloy","lastPublishedDoi":"10.21203/rs.3.rs-5849361/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5849361/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePowder Bed Fusion\u0026mdash;Laser Beam/Metal (PBF-LB/M) is considered one of the most versatile and promising among the Additive Manufacturing (AM) techniques, enabling the fabrication of dimensionally precise parts due to the lower thermo-mechanical distortions introduced in the process. Moreover, PBF-LB/M facilitates the manufacturability of several metal alloys, such as nickel-based ones, retaining acceptable structural integrity that can be improved with the aid of different post-process operations on the final part. These advantages and capabilities of the process allow the manufacturing of geometrically and dimensionally complex parts, such as thin walls and intricate structures. The aim of this work is to study the impacts on microstructure and mechanical properties based on tensile specimens\u0026rsquo; thickness produced in Hastelloy-X alloy. The specimens were produced as per ASTM E8/E8M-24. The material microstructure is evaluated through a grain size and orientation and porosity percentage analysis using an optical microscope. The material mechanical properties are assessed through a tensile test at room temperature on dog bone specimens that were fabricated both parallel and perpendicular to the building direction. The results obtained in this work show a significant reduction in mechanical properties as a function of specimen thickness, resulting from a gradual decrease from the baseline to 40% of it. Specifically, there was a 16% decrease in the Ultimate Tensile Strength, a 23% reduction in the Young's Modulus, and a 41% decrease in the Elongation at Break. In addition, it has been observed that specimens\u0026rsquo; printing orientation has an important influence on mechanical properties, regardless of the specimen thickness. An analysis of porosity, grain size, and orientation evaluates the microstructure of tested specimens, revealing significant differences between horizontal and vertical specimens.\u003c/p\u003e","manuscriptTitle":"Investigation on Microstructure and Mechanical Properties of Hastelloy-X Thin Wall Specimens obtained by PBF-LB/M","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-28 13:18:48","doi":"10.21203/rs.3.rs-5849361/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":"8a5bd698-ec77-4f6d-8bcf-9e6e7a8544cd","owner":[],"postedDate":"March 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-04-14T16:39:40+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-28 13:18:48","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5849361","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5849361","identity":"rs-5849361","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}