Study of the plasma nitriding effect on high-speed steel drills: performance in dry machining

Study of the plasma nitriding effect on high-speed steel drills: performance in dry machining | 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 Study of the plasma nitriding effect on high-speed steel drills: performance in dry machining Petteson Linniker Carvalho Serra, Weslley Rick Viana Sampaio, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6490563/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract High-speed steel is one of the most widely used materials in machining tools. However, applications such as dry machining require superior properties to those presented by conventional tools. Surface treatments such as plasma nitriding are alternatives to improve these properties. This work proposes a study of the application of plasma nitriding with lower temperatures and times (300°C, 350°C and 400°C, for 2 hours) on high-speed steel tools to be evaluated in dry drilling process. The samples were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction with application of Rietveld routine, surface microhardness, microhardness profile and average surface roughness (Ra) measurements. Then, the tools were submitted to performance simulation in a CNC machining center and analyzed based on measurements of the flank wear evolution, the required electric current by the machine during cutting times and by the diameter and surface roughness of the machined holes. The results showed an increase in flank wear with the treatment at 400°C due to the higher surface roughness, while the tools treated at lower temperatures showed better performance than the untreated tool, evidenced by the lower wear rate in the steady state, by machining all holes within tolerance limits and by the lower surface roughness of the holes. It was observed, thus, that treatments at lower temperatures produce conditions of greater balance between hardness and surface roughness, contributing to higher wear resistance. High-speed steel plasma nitriding roughness drilling dry machining Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 1 Introduction High-Speed Steel (HSS) is still one of the main materials used for tools manufacturing intended for machining [ 1 ]. Its wide application is especially due to its lower cost [ 2 ] and its high toughness [ 3 ], which is indispensable for application in small tools [ 4 ] and in some specific operations such as deep drilling [ 5 ], characterized by a higher probability of tool fracture. These conditions restrict the use of carbide tools, even in the face of their greater resistance to surface wear [ 3 , 6 , 7 ]. Even with the advantages shown, which justify the wide application of high-speed steel in industry, productivity and surface quality requirements are growing and increase the demand for more efficient tools that combine properties such as high hardness, high wear resistance, thermal stability and high oxidation resistance. Advanced processes such as dry machining, for example, require superior properties to those presented by conventional high-speed steel tools (without treatment) [ 8 ]. In this context, surface treatments emerge as a good alternative to improve their performance. Surface treatments include the deposition of coatings by PVD (Physical Vapor Deposition) [ 9 ] or CVD (Chemical Vapor Deposition) [ 10 ] and plasma nitriding [ 5 ]. In nitriding, the nitrided layer can be composed of a layer of nitrides, characterized by high hardness, but which depending on the thickness can present brittle behavior, and by a diffusion zone, which presents as a characteristic a gradual reduction of hardness from the surface to the substrate, being free of existing discontinuities at interfaces of nitride layers or films deposited by PVD or CVD [ 11 , 12 ]. The relative proportions of these zones can be controlled by the treatment variables (temperature, time and mainly the composition of the gases) which consists of a fundamental advantage of plasma nitriding in relation to other thermochemical treatments, even allowing the obtaining of surfaces formed only by diffusion zone or very thin layer of nitrides [ 13 , 14 ]. Although nitriding can be applied to increase the hardness and wear resistance of tools, due attention should be given to surface roughness, the increase of which is inherent to the process, since it consists of a sputtering treatment [ 15 ]. This increase, when evaluated in isolation, contributes to the evolution of tool wear [ 16 , 17 ]. Thus, it is necessary to monitor the evolution of roughness with treatments so that its adverse impact is minimal in relation to the impact of increasing hardness and surface stability. This concern grows in the case of dry machining, due to the absence of cutting fluid and, as a consequence, the greater difficulty of chip flow. In this study, the application of plasma nitriding was evaluated combining low treatment times (2 hours) and temperatures (300°C, 350°C and 400°C) in commercial M2 high-speed steel drills. The objective is to evaluate the feasibility of applying these tools in dry machining operations, seeking to identify a condition capable of improving the tribological behavior through a surface that combines high hardness, mechanical stability (without layer of compounds) and maintenance of roughness sufficiently low. The differential of this work is to evaluate, in addition to the influence on the evolution of tool wear, the effect on the dimensional and surface quality of the holes. 2 Materials and Methods N-type HSS drills [ 18 ], were used, with a cutting length of 75 mm, total length of 117 mm and diameter of 8 mm. Half of the tools had the tip cut to create a flat surface that would enable the application of characterization techniques, the others had the geometry preserved to perform the performance test. After the cutting operation, the generated surfaces were sanded with water sandpaper with a granulometry of 80, 220, 360, 400, 600 and 1200 mesh and finished with mechanical polishing on felt disc using diamond paste of 3 µm granulometry. They were then washed in running water, immersed in acetone along with the uncut tools and taken to the ultrasound equipment, where they were kept for 20 minutes. After cleaning, they were dried with a common dryer. The base, used to keep the samples and tools in a vertical position, was sanded with 80 mesh sandpaper. Then, they were washed with running water and immersed in acetone in the ultrasound equipment for 20 minutes. After that time, they were dried with a common dryer. Each treatment condition was applied in two uncut drills and in two samples (drills with the tip cut off), as shown in Fig. 1 . A support was used to keep the tools in a vertical position during the treatment, but the through holes allow direct contact of the tools with the sample holder (cathode). Conventional nitriding was carried out using a direct current source with a capacity of up to 1200 V. The treatment temperatures were 300°C, 350°C and 400°C, the lowest values when compared to previous works of M2 steel nitriding [ 12 , 19 ] are due to the large length of the samples and the temperature gradient established during conventional nitriding [ 20 ]. As demonstrated in Serra et al. [ 5 ], the recorded temperatures are measured at the base of the tools, if they could be measured at the tips they would be much higher. All treatments were preceded by a pre-sputtering with hydrogen atmosphere at 300°C, time of 1 hour and pressure of 8.0‧10 2 Pa. Then the atmosphere was changed to a mixture of hydrogen and nitrogen (H2:N2 = 64 sccm:6 sccm) and the voltage was adjusted until the treatment temperature was reached. The composition of the atmosphere was chosen so that it did not exceed 10% nitrogen, so as to inhibit the formation of the compound layer and favor the formation of a more stable layer for application in the tools [ 13 , 14 , 21 ]. Previous studies have shown that a high thickness compounds layer makes the surface brittle [ 19 , 22 ] which may contribute to the increased possibility of cutting edge breakage or layer detachment. Table 1 summarizes the treatment conditions applied to each sample and the nomenclature used for each sample. Table 1 Nomenclature of samples and their respective treatment parameters used Sample Treatment Conditions Pre-Sputtering Sputtering Temperature (°C) Pressure (Pa) Time (h) Gases H 2 (sccm) Temperature (°C) Pressure (Pa) Time (h) Gases H 2 : N 2 (sccm) UT - - - - - - - - N300 300 8,0 10 2 1:00 60 300 1,0 10 3 2:00 64:6 N350 300 8,0 10 2 1:00 60 350 1,0 10 3 2:00 64:6 N400 300 8,0 10 2 1:00 60 400 1,0 10 3 2:00 64:6 The tools that had the tip previously cut were separated for characterization, where a transverse cut was made to separate the upper part, reducing the size of the sample and facilitating its handling. A sample relative to each treatment condition was embedded in bakelite with the lateral surface facing down and then sanded using 80, 220, 360, 400, 600 and 1200 mesh sandpaper. After sanding, the samples were polished on a felt disc using alumina with a granulometry of 3 µm. Cross-sectional samples were used to obtain Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) images of the cross-sectional surface and for Vickers microhardness (HV) measurements used in the profile. The other samples were used for XRD characterization, to obtain surface morphology images, and for surface roughness and microhardness measurements. X-ray diffraction (XRD) was performed using a XRD-6000 Shimadzu diffractometer operating at 40 kV and 30 mA, Cu-Kα radiation with λ = 0.154060 nm and with a range of 35° to 105°. Rietveld analysis was performed using the ReX Powder Diffraction software (version 9.2). The morphological aspects of the surface and the thickness and uniformity of the compounds layer were observed in a Scanning Electron Microscope (SEM) from FEI Company, model Quanta TM 250-FEG. Before being taken to the SEM, the transverse samples were chemically attacked by immersion in a 4% Nital solution (4% nitric acid and 96% ethyl alcohol) for a time between 5 and 7 seconds. The thickness and uniformity of the diffusion zone was observed using an Olympus optical microscope, model CX31. The surface microhardness and microhardness profile were evaluated using an Insize microdurometer, model ISH-TDV 100. For surface microhardness, the measurement was repeated 5 times using a load of 0.05 kgf and an indentation time of 15 s. For the measurements used in the profile, the same load conditions and indentation time were maintained, measurements being taken every 5 µm perpendicular to the surface up to a depth of 80 µm. At each measurement, the indenter was laterally displaced 15 µm to avoid the influence of previous indentations, and for a distance of 0 µm, the microhardness value obtained for the surface was considered. The average roughness (Ra) measurements were made with the aid of a SJ210 Mitutoyo rugosimeter, respecting the provisions of NBRISO4288 [ 23 ]. The performance simulation of the tools was carried out in a CNC machining center. The machined material was SAE 1045 steel due to its wide use in the metalworking industry and low cost [ 24 ]. Machining planning was carried out in such a way as to allow the machining of the maximum number of holes in a specimen, respecting the minimum distance between holes and between holes and the edge of the specimens. According to Rodrigues et al. [ 25 ], this distance is 1.5 times the diameter of the holes. Thus, it was established that a maximum of 14 holes would be machined in each block. It was established that the machined holes would be non-through holes, “blind holes”. Four stopping criteria (end of life) were adopted: complete tool failure (breakage, including edge chipping), excessive occurrence of noise, the maximum number of 14 holes (1 block) and the maximum flank wear (VB máx ) of 0.5 mm. The cutting parameters used for drilling were defined based on technical catalogs [ 26 , 27 ] that recommend a cutting speed of 20 m/min (rotation of 796 RPM) and feed of 0.19 mm/rev (151 mm/min) for high-strength carbon steel machining (above 27 HRC), these parameters were adjusted in a pre-test using an untreated drill and tape-shaped chip formation was verified, the cutting speed was increased until the chip size was adjusted and the feed per revolution was decreased. After adjustment, the cutting speed was fixed at 35 m/min (1393 RPM) and the feed per revolution at 0.04 mm/rev (50 mm/min). The depth of the holes was 20 mm, using intermittent feed (woodpecker feed) to help the chip removal and contribute to the machining of holes with good dimensional quality [ 3 , 5 ]. An OSFL (One-Step Feed-Length) feed of 5 mm was adopted for each step. The measurement of the progressive wear of the tools was done by image, with the ImageJ software that allows the conversion of pixels into millimeters. Images were acquired every 2 complete holes (defined as a machining cycle) using a portable microscope coupled to the machine table, which eliminated the need to remove the tool at the end of each cycle and ensured the same approximation between the tool and the microscope in each capture. This approximation was made within the machining program. The RMS electric current was monitored by a system formed by three hall effect sensors, model SCT-013-000, with a range from 0 to 100 mA, a data acquisition board mounted with voltage divider resistors, load resistor, filter capacitor and an Atmega 2560 microcontroller. The values were obtained for each machining cycle (2 holes). The graphical pattern obtained for the useful machining cycle (cutting motion and approximation/retreat motion) is shown in Fig. 2 . Note that the cycle alternates between cut and retreat/approximation motions, which is characteristic of the intermittent cutting cycle. After data acquisition, data referring only to the cutting motion (which can be directly associated with the performance of the tools) were separated, and the initial and final values of each cutting subcycle were removed, thus avoiding the influence of the approximation/retreat motion, and the average for each tool was calculated. The dimensional tolerance of the holes was evaluated using the ImageJ software to convert pixels into mm and then transferring the images to the AutoCAD software (version 2022) from AutoDesk, applying a scale factor and using the 3-points-circle and diameter-dimension functions. Five measurements were made for each hole. According to the tool manufacturer Dormer [ 28 ] the tolerance for general drilling is H12. Thus, the minimum and maximum dimensions of the holes must be, respectively, 8.000 mm and 8.150 mm. The surface roughness of the holes was evaluated by measures of average roughness (Ra) made with the aid of a SJ210 Mitutoyo rugosimeter and in accordance with the NBRISO4288 [ 23 ]. In each hole, 20 measurements were taken, varying the position of the probe by 90° every 5 measurements. 3 Results and Discussion 3.1 XRD Analysis Figure 3 shows the XRD patterns obtained for the untreated and treated samples, together with the results calculated by the Rietveld refinement application, including quantitative analysis of the phases obtained. The pattern obtained for the untreated sample, Fig. 3 a, was related to a combination of 4 distinct phases recorded in the Inorganic Crystal Structure Database (ICSD) and used to determine the theoretical profile: iron (Fe) 64795 [ 29 ], iron-molybdenum (Mo 0.03 Fe 0.97 ) 632630 [ 30 ], carbides M type (M 6 C) 672333 [ 31 ], chromium carbide (Cr 23 C 6 ) 2837 [ 32 ]. The pattern obtained for the untreated sample, Fig. 3 a, was related to a combination of 4 distinct phases recorded in the Inorganic Crystal Structure Database (ICSD) and used to determine the theoretical profile: iron (Fe) 64795 [ 29 ], iron-molybdenum (Mo 0.03 Fe 0.97 ) 632630 [ 30 ], carbides M type (M 6 C) 672333 [ 31 ], chromium carbide (Cr 23 C 6 ) 2837 [ 32 ]. These phases agree with the composition typically suggested for M2 high-speed steel and show the predominance of a Mo 0.03 Fe 0.97 phase, which corresponds to a solid solution of molybdenum in iron, and can be observed a considerable amount of carbide type Cr 23 C 6 and type M 6 C. The GOF (Goodness-Of-Fit) adjustment parameter equal to 1.33 obtained in the refinement, together with the visual adjustment between the experimental (green) and calculated (red) profiles, confirm the agreement with the reported phases [ 33 , 34 ]. For the three treatment conditions, Fig. 3 b-d, in addition to the four phases observed for the untreated sample (UT), two more phases were identified, also registered in the Inorganic Crystal Structure Database (ICSD) and added to the first four for the determination of the theoretical profile: expanded austenite (S) (FeN 0,095 ) 31908 [ 35 ] and iron nitride Fe 4 N 60195 (JACK, 1948). The predominance of the Mo0.03Fe0.97 phase, as observed for the untreated sample, is due to the great influence of the substrate on the measurements. The GOF values obtained for the three samples (1.17; 1.16 and 1.14; for N300, N350 and N400, respectively) indicate a good agreement between the experimental profile and the associated phases [ 33 , 34 ]. The percentages presented indicate a growth of the diffusion zone when the treatment temperature is increased from 300°C to 350°C, evidenced by the greater amount of S phase. This behavior is the most common and it was observed in other works such as that of Abreu et al. [ 12 ]. On the other hand, the unusual behavior of diffusion zone reduction with the increase in temperature, presented by the sample treated at 400°C, can be explained by the greater amount of Fe 4 N phase and by the higher volume of Cr 23 C 6 precipitates. Young et al. [ 36 ] also reported the formation of these precipitates in the austenitic stainless steel nitriding with an atmosphere of N 2 and H 2 . The presence of these carbides, as well as higher levels of the Fe 4 N phase, act as barriers to nitrogen diffusion [ 37 ]. 3.2 Optical microscopy and scanning electron microscopy analysis Figure 4 shows the surface morphology of an untreated sample and samples after nitriding at different temperatures. For the untreated sample, Fig. 4 a, a more uniform surface can be observed only with the presence of some regions that can be associated with metallic inclusions. For the treated samples, a surface with a more heterogeneous morphology can be observed, again characterized by the presence of inclusions and precipitates in greater volume. These precipitates can be associated with the presence of chromium carbides shown in the XRD results, section 3.1 , and they were also observed in the work by Li et al. [ 37 ]. The increase in the volume of precipitates on the surface of the treated samples agrees with the greater volume of Cr 23 C 6 phase, also shown in the XRD results and it is related to the decarburization caused by the addition of nitrogen, the carbon diffuses in the opposite direction to the nitrogen and it is free to combine with elements such as iron and chromium. The presence of carbides on the surface is an indication of the non-formation of a compounds layer, as otherwise they would occupy the interface between this layer and the diffusion zone [ 38 ]. A more irregular surface can also be observed for the sample treated at a temperature of 400°C, evidenced here by the defects indicated in Fig. 4 d by indications in blue. This behavior may be associated with the increase in sputtering intensity with increasing temperature. Works such as that of Morgiel et al. [ 39 ] showed a similar variation. Figure 5 shows the optical microscopy of the nitrided samples, highlighting the formation of the diffusion zone for all treatment conditions applied, which portrays the efficiency of the treatment even with nitriding time of only 2 h. Comparing the results shown in Fig. 5 a and Fig. 5 b, an increase in the average thickness of the diffusion zone from 24.09 µm to 28.59 µm was observed with the increase in temperature from 300°C to 350°C, this behavior is the most expected with temperature variation and it was observed in other works [ 12 ]. With the increase in temperature to 400°C, the diffusion zone presented only 21.57 µm even with the increase in temperature, which confirms the behavior suggested by the smaller volume of S phase presented in the XRD results and once again can be related to the greater volume of the Cr 23 C 6 and Fe 4 N phases that act as barriers to nitrogen diffusion [ 37 , 38 ]. Figure 6 shows the cross-section surface images of the samples obtained by SEM. All samples have a martensitic microstructure, characterized by the needles highlighted in Fig. 6 , as a result of the quenching treatment applied by the manufacturer. It can be observed in Fig. 6 b-c that none of the treated samples formed a compounds layer, showing the efficiency of the treatment parameters defined in the formation of a nitrided layer consisting only of a diffusion zone. Thus, the Fe 4 N iron nitride presented in the XRD results can be associated only with the precipitation of nitrides in the form of needles within the diffusion zone and this corroborates with the results presented by Danelon et al. [ 40 ]. Visually, it is possible to observe a greater density of needles in the nitrided samples, Fig. 6 b-d, in relation to the untreated sample, Fig. 6 a, mainly for the nitrided sample at 400°C, this is due to the combined presence of martensite needles and Fe 4 N in the diffusion zone and it is in agreement with the results presented in section 3.1 . 3.3 Vickers Surface Microhardness and Vickers Microhardness Profile Figure 7 presents the Vickers surface microhardness results for the untreated sample (UT) and for the treated samples. It is initially observed that all treatment conditions applied here contributed to the increase in surface microhardness, with the highest result presented by the N400 sample, which exceeded by 1.95 times the average value presented by the UT sample. The increasing behavior of surface microhardness with treatment temperature can be associated initially with the combined effect of the increase in the diffusion zone thickness and the content of Fe 4 N, when the temperature is increased from 300°C to 350°C. When the temperature is increased from 350°C to 400°C, although a reduction in the thickness of the diffusion zone is presented, the Fe 4 N content was still increasing and it was evidenced both quantitatively in section 3.1 and qualitatively in section 3.2 and justifies this increase. Figure 8 shows the Vickers microhardness profiles obtained from measurements made in the cross-section of the samples. The horizontal line (dashed red) shows the NHT value (from German, n itrier h ärte t iefand – nitriding depth) which corresponds, according to DIN 50190 standard (DEUTSCHES INSTITUT FÜR NORMUNG, 1979) to a minimum gain of 50 HV above the core hardness value. For the untreated sample, a profile is observed in which the values are close to the average microhardness value of the substrate. In the treated samples, it can be seen that the surface microhardness gradually decreases from the surface microhardness until it assumes values comparable to that of the core. N400 sample, although presenting a higher value for surface microhardness, has a more vertical profile than samples N300 and N350, which represents a more abrupt hardness reduction, due to this behavior, it can be noted that the calculated value for NHT is reached at a lower depth (38µm). Applying the method to the N300 and N350 samples, we obtained diffusion zone thicknesses equal to 45µm and 50 µm, respectively. The values obtained with the method described in DIN 50190 [ 41 ] are generally higher than those obtained by optical microscopy images, Fig. 4 . However, they present the same behavior indicated both in the results of optical microscopy and by the quantitative analysis of the phases in the XRD data shown in Fig. 6 , confirming that initially there is a growth of the diffusion zone with the increase in the treatment temperature up to 350°C, followed by a reduction when the treatment temperature is 400°C. 3.4 Surface Roughness Figure 9 presents the surface roughness results of the UT sample and the treated samples. The dashed horizontal lines show the limits of the surface roughness classes in which the samples fit according to the Associação Brasileira de Normas Técnicas [ 42 ], which classifies the finishing of the samples according to 12 classes, from N1 to N12, where N1 represents the best state of surface finish and N12 the worst state of surface finish. All applied treatments caused an increase in surface roughness in relation to the untreated sample, this behavior is characteristic of conventional plasma nitriding and it is mainly due to surface sputtering and volumetric expansion of the network associated with nitrogen diffusion [ 43 – 45 ]. The severity of sputtering grows with increasing treatment temperature [ 39 , 46 ], which explains the increase in average surface roughness in the same direction. In treatments at lower temperatures, N300 and N350, the surface quality changes from N3 to N4, while for the N400 sample there is a gain of two roughness classes, from N3 to N5. Thus, considering only the roughness, it is expected that the samples treated at lower temperatures present more significant results in the face of abrasive wear operations. 3.5 Wear analysis Figure 10 shows the tool life curves obtained after the tool performance test. For all tools, the stopping criterion of the maximum number of holes (14 holes) prevailed, since none of the tools showed significant failure and did not even reach a maximum flank wear of 0.50 mm. The evolution of tool wear is similar to the classic wear curve (Lorentz), characterized by an initial zone with high wear rate (break-in period), followed by a zone with slow increase in the wear indicator (steady-state wear region) [ 4 , 47 ]. The first significant difference in behavior with the treatments is observed for the N400 tool, the treatment resulted in an extension of the break-in phase to the sixth hole, which contributed to this tool presenting the highest flank wear in all measurement stops. The less noble behavior of the N400 sample can be associated with the increase in surface roughness, revealed by the results shown in Fig. 9 . The work by Do Nascimento Rosa et al. [ 48 ] showed a similar relation to this behavior. Additionally, this was the sample that presented the highest surface microhardness value (higher resistance to plastic deformation), which should contribute to a lower level of flattening on the surface and, consequently, to a higher coefficient of friction [ 49 ]. On the other hand, the treatments applied at lower temperatures contributed to a reduction in the flank wear rate, especially after the sixth hole. The direct comparisons of the N300 and N350 curves with the UT curve in Fig. 10 reveal a lower slope of the curves within the steady state, this shows a more efficient balance between the increases in surface microhardness and the consequent increase in roughness due to the characteristics of the process (sputtering). This result shows that the increase in surface roughness cannot be neglected compared to the increase in hardness obtained with nitriding and it reveals that treatments at lower temperatures result in a better balance between these properties. 3.6 Electric current Figure 11 presents the average data of required current during the performance simulation. It is known that the consumed electrical power, as well as the consumed mechanical power, are proportional to the values of electric current required by the machine tool [ 50 , 51 ]. The data presented correspond only to the time intervals in which material removal actually occurred, see section 2.4. The results show higher efficiency of N300 and N350 samples. This behavior is in accordance with the one presented in Fig. 10 , since the machining strength increases with tool wear and it is also a consequence of the low roughness achieved even after treatment. Thus, it can be affirmed that the treatments, besides contributing to increase the wear resistance of the tools, contributed to a reduction in machining power. On the other hand, the N400 sample presented the highest average value of consumed current, agreeing with the results of surface roughness (directly related to friction) and reinforcing the negative effect of treatments at high temperatures. 3.7 Holes measurement (Dimensional Tolerance) Figure 12 presents the values of the holes diameters measures, together with the maximum and minimum diameters established by the ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS ( 1995) for the dimensional tolerance 8H12, defined for drilling operations in general. Only one of the holes in the untreated sample, Fig. 12 a, was outside the dimensional tolerance (hole 2), representing a process failure that corresponds to 7.14% of the performed holes. All the treated tools produced holes within the diameter range established by the 8H12 dimensional tolerance, allowing to ensure the good dimensional quality of the holes machined with the treated tools, including those performed by the N400 drill, which showed the highest level of wear, but still lower than the maximum flank wear of 0.50 mm defined as stopping criterion. This result contributes to reinforce that none of the tools reached the end of tool life and, above all, proves the ability of the tools to machine dry holes within the required dimensional quality. 3.8 Hole roughness Figure 13 presents the results of average surface roughness (Ra) of the machined holes. Figure 13 a-c show the comparison of the results obtained for each treated tool with those obtained for the untreated tool. Figure 13 d shows the direct comparison between those that presented the best surface quality, N300 and N350. All the holes presented surface quality N9 and no change in roughness class could be observed with the treatments, however a change to lower values can be observed when the holes were machined with the N350 tool and especially when using the N300 tool, Fig. 13 b and Fig. 13 a, respectively. Figure 13 d reinforces the obtaining of holes with lower average roughness for treatments at lower temperatures. This result shows a relation between the tools roughness, shown in Fig. 9 , and the holes roughness, so that tools with lower roughness tend to produce holes with lower surface roughness, this behavior is related to the ease of chip disposal provided by less rough surfaces, which is even more important in dry machining, since one of the most important functions of the cutting fluid is to assist in chip disposal. The N400 sample, Fig. 13 c, although presenting higher average surface roughness than the UT sample, had holes with equivalent roughness values, this result does not compare the relation presented, since nitriding modifies the surface of the tools contributing to a lower coefficient of friction for the same roughness level. 4 Conclusions Cross-section images confirmed the formation of the nitrided layer after 2 hours of treatment. The layer was formed only by a diffusion zone, showing the efficiency of the chosen parameters in inhibiting the growth of a brittle compound layer. The data obtained from Rietveld refinement confirmed this formation and the other conclusions are summarized below: All treatments resulted in an increase on surface microhardness and in the formation of a hardness gradient from the surface to the center, which contributed to greater stability of the nitrided layers. An increase in surface roughness was observed for all samples, an expected behavior due to surface sputtering. In the sample treated at 400°C, the value observed for the average roughness was much higher than that presented by the other samples. The tool life curves revealed that the treatment at 400°C prolonged the break-in phase and resulted in the condition with the highest flank wear, this behavior was associated with a considerable increase in roughness. The treatments at lower temperatures, on the other hand, contributed to the reduction in the wear rate within the steady-state. The results of electric current showed that machining with the tool treated at 400°C showed higher current values, suggesting higher consumed power. All treated tools machined holes respecting the 8H12 dimensional tolerance defined for general drilling operations. This behavior was better than that of the untreated sample, which had one of the holes with a dimension greater than that defined by the tolerance limit. Regarding surface quality, the tools with lower roughness also produced holes with lower roughness. Declarations Funding This study was financial support was provided by National Council for Scientific and Technological Development. Conflicts of interest/Competing interests 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. Authors' contributions Petteson Linniker Carvalho Serra: Methodology, Formal analysis, Data curation, Writing - Original draft Writing-Review & editing. Weslley Rick Viana Sampaio: Formal analysis, Writing-Review & editing. Patrick Abreu de Oliveira: Methodology, Formal analysis, Data curation. Renan Matos Monção: Methodology, Formal analysis, Data curation. José Ribamar do Carmo Pereira Júnior: Methodology, Formal analysis, Data curation. Paulo Roberto Queiroz de Almeida: Methodology, Formal analysis, Data curation. Wenio Fhara Alencar Borges: Methodology, Formal analysis, Writing-Review & editing. Thércio Henrique de Carvalho Costa: Conceptualization, Resources, Analysis formal, Writing-Review & editing. Marcos Guilherme Carvalho Braulio Barbosa: Analysis formal, Resources, Data curation, Analysis formal, Writing-Review & editing. Rômulo Ribeiro Magalhães de Sousa: Conceptualization, Methodology, Resources, Analysis formal, Supervision, Funding acquisition, Writing-Review & editing. References Shi C, Yu A, Wu J, et al (2017) Study on position of laser cladded chip breaking dot on rake face of HSS turning tool. 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Rio de Janeiro, p 79 Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Minor Revisions Needed 01 Jul, 2025 Reviewers agreed at journal 08 May, 2025 Reviewers invited by journal 08 May, 2025 Editor assigned by journal 08 May, 2025 First submitted to journal 05 May, 2025 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. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6490563","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":453781824,"identity":"6a4c3821-8d46-4c26-8745-1ab398accc78","order_by":0,"name":"Petteson Linniker Carvalho 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1","display":"","copyAsset":false,"role":"figure","size":124065,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of the arrangement of the uncut drills and samples (cut drills) during the treatment of plasma nitriding\u003c/p\u003e","description":"","filename":"image1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/0f7a840da06347217eb32649.jpeg"},{"id":82618450,"identity":"ddf94aae-0a20-47b8-bb02-ad3b455368e3","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":91162,"visible":true,"origin":"","legend":"\u003cp\u003ePattern of the current data obtained for a machining cycle (two holes) showing the approximation/retreat and cutting motions, which were the data effectively used for electric current analysis\u003c/p\u003e","description":"","filename":"image2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/b35b64ad5138b51a2e82a00f.jpeg"},{"id":82618465,"identity":"09369e35-f6a7-4fae-a5ff-66b27eebe592","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":121626,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray diffraction patterns of samples with quantitative phase result presentation obtained by Rietveld refinement: (a) UT; (b) N300; (c) N350 e (d) N400\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/34aaf81c966e8d19a644ea07.jpeg"},{"id":82618453,"identity":"06410185-3bd9-4cc0-ada6-f2f9969a6018","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":700347,"visible":true,"origin":"","legend":"\u003cp\u003eImages obtained by Scanning Electron Microscopy (SEM) showing the surface morphology of the samples: (a) UT; (b) N300; (c) N350 e (d) N400\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/7bf350981d2bc78d97e58563.jpeg"},{"id":82618456,"identity":"6a0069d6-7ac6-4513-af76-02c3da166f9a","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1034547,"visible":true,"origin":"","legend":"\u003cp\u003eCross-section optical microscopy of the treated samples showing the diffusion zone formed with nitriding: (a) N300; (b) N350 e (c) N400\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/4c4e55f40b0743be90eb3bb3.jpeg"},{"id":82618457,"identity":"8cb97864-572e-4df4-ac67-dd60ab184b55","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":429354,"visible":true,"origin":"","legend":"\u003cp\u003eImages obtained by Scanning Electronic Microscopy of the treated samples cross-section showing the formation of the compounds layer: (a) N300; (b) N350 e (c) N400. In (d) it is possible to observe the comparison between the average thickness of these layers\u003c/p\u003e","description":"","filename":"image6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/012e461946f3f37959070b20.jpeg"},{"id":82619681,"identity":"d8205a2c-e71a-4ea4-866d-218d51f5a7eb","added_by":"auto","created_at":"2025-05-13 12:09:41","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":97693,"visible":true,"origin":"","legend":"\u003cp\u003eVickers microhardness measured on the surface of the untreated sample (UT) and of nitrided samples: N300, N350 and N400\u003c/p\u003e","description":"","filename":"image7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/8523172cf995d95ba17d29a9.jpeg"},{"id":82618468,"identity":"3ec45e01-2b6c-46ab-83cb-7b6f9643a71e","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":185014,"visible":true,"origin":"","legend":"\u003cp\u003eVickers microhardness profile of the untreated sample (UT) and nitrided samples: N300, N350 and N400\u003c/p\u003e","description":"","filename":"image8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/eadb6767694198251cec0478.jpeg"},{"id":82619687,"identity":"ce3061d1-ddcd-4abb-b97f-85b1b21145a1","added_by":"auto","created_at":"2025-05-13 12:09:42","extension":"jpeg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":119069,"visible":true,"origin":"","legend":"\u003cp\u003eRoughness of the untreated sample and nitrided samples: N300, N350 and N400\u003c/p\u003e","description":"","filename":"image9.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/8099f3d26f4dc0ad440e42e2.jpeg"},{"id":82618473,"identity":"d8a80a08-e14b-450d-a4a7-2fd408dc6aa2","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":165522,"visible":true,"origin":"","legend":"\u003cp\u003eWear curves for untreated (UT) and treated tools: N300, N350 and N400\u003c/p\u003e","description":"","filename":"image10.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/2ee559eb4b3f17f9acbe11d9.jpeg"},{"id":82619682,"identity":"6c427ec5-df5b-40ee-99bb-e0ae6c0a891b","added_by":"auto","created_at":"2025-05-13 12:09:41","extension":"jpeg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":90826,"visible":true,"origin":"","legend":"\u003cp\u003eConsumed average current rate of untreated (UT) and treated tools: N300, N350 and N400\u003c/p\u003e","description":"","filename":"image11.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/fe13c93acfb01ea765b98373.jpeg"},{"id":82618462,"identity":"dcb29874-2acb-4820-ad64-e5a6ae9494bc","added_by":"auto","created_at":"2025-05-13 12:01:41","extension":"jpeg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":262508,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of the holes machined with the tools: (a) UT; (b) N300; (c) N350 e (d) N400\u003c/p\u003e","description":"","filename":"image12.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/d7fa6e35436744442a1d3b9b.jpeg"},{"id":82618480,"identity":"a08a5337-7194-4dd2-bf5b-3970ab2a09b0","added_by":"auto","created_at":"2025-05-13 12:01:42","extension":"jpeg","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":305011,"visible":true,"origin":"","legend":"\u003cp\u003eRoughness of the holes\u003c/p\u003e","description":"","filename":"image13.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/d7881fe9c8d75074ce24deb6.jpeg"},{"id":82622181,"identity":"0d9f9f31-40f5-4264-be07-a06f6f4ec8c0","added_by":"auto","created_at":"2025-05-13 12:25:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4704706,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6490563/v1/c8aa7959-f95a-4594-b746-d0e7be1d8445.pdf"}],"financialInterests":"","formattedTitle":"Study of the plasma nitriding effect on high-speed steel drills: performance in dry machining","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eHigh-Speed Steel (HSS) is still one of the main materials used for tools manufacturing intended for machining [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Its wide application is especially due to its lower cost [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] and its high toughness [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], which is indispensable for application in small tools [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] and in some specific operations such as deep drilling [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], characterized by a higher probability of tool fracture. These conditions restrict the use of carbide tools, even in the face of their greater resistance to surface wear [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEven with the advantages shown, which justify the wide application of high-speed steel in industry, productivity and surface quality requirements are growing and increase the demand for more efficient tools that combine properties such as high hardness, high wear resistance, thermal stability and high oxidation resistance. Advanced processes such as dry machining, for example, require superior properties to those presented by conventional high-speed steel tools (without treatment) [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In this context, surface treatments emerge as a good alternative to improve their performance.\u003c/p\u003e \u003cp\u003eSurface treatments include the deposition of coatings by PVD (Physical Vapor Deposition) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] or CVD (Chemical Vapor Deposition) [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and plasma nitriding [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In nitriding, the nitrided layer can be composed of a layer of nitrides, characterized by high hardness, but which depending on the thickness can present brittle behavior, and by a diffusion zone, which presents as a characteristic a gradual reduction of hardness from the surface to the substrate, being free of existing discontinuities at interfaces of nitride layers or films deposited by PVD or CVD [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The relative proportions of these zones can be controlled by the treatment variables (temperature, time and mainly the composition of the gases) which consists of a fundamental advantage of plasma nitriding in relation to other thermochemical treatments, even allowing the obtaining of surfaces formed only by diffusion zone or very thin layer of nitrides [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough nitriding can be applied to increase the hardness and wear resistance of tools, due attention should be given to surface roughness, the increase of which is inherent to the process, since it consists of a sputtering treatment [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This increase, when evaluated in isolation, contributes to the evolution of tool wear [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Thus, it is necessary to monitor the evolution of roughness with treatments so that its adverse impact is minimal in relation to the impact of increasing hardness and surface stability. This concern grows in the case of dry machining, due to the absence of cutting fluid and, as a consequence, the greater difficulty of chip flow.\u003c/p\u003e \u003cp\u003eIn this study, the application of plasma nitriding was evaluated combining low treatment times (2 hours) and temperatures (300\u0026deg;C, 350\u0026deg;C and 400\u0026deg;C) in commercial M2 high-speed steel drills. The objective is to evaluate the feasibility of applying these tools in dry machining operations, seeking to identify a condition capable of improving the tribological behavior through a surface that combines high hardness, mechanical stability (without layer of compounds) and maintenance of roughness sufficiently low. The differential of this work is to evaluate, in addition to the influence on the evolution of tool wear, the effect on the dimensional and surface quality of the holes.\u003c/p\u003e"},{"header":"2 Materials and Methods","content":"\u003cp\u003eN-type HSS drills [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], were used, with a cutting length of 75 mm, total length of 117 mm and diameter of 8 mm.\u003c/p\u003e \u003cp\u003eHalf of the tools had the tip cut to create a flat surface that would enable the application of characterization techniques, the others had the geometry preserved to perform the performance test. After the cutting operation, the generated surfaces were sanded with water sandpaper with a granulometry of 80, 220, 360, 400, 600 and 1200 mesh and finished with mechanical polishing on felt disc using diamond paste of 3 \u0026micro;m granulometry. They were then washed in running water, immersed in acetone along with the uncut tools and taken to the ultrasound equipment, where they were kept for 20 minutes. After cleaning, they were dried with a common dryer.\u003c/p\u003e \u003cp\u003eThe base, used to keep the samples and tools in a vertical position, was sanded with 80 mesh sandpaper. Then, they were washed with running water and immersed in acetone in the ultrasound equipment for 20 minutes. After that time, they were dried with a common dryer.\u003c/p\u003e \u003cp\u003eEach treatment condition was applied in two uncut drills and in two samples (drills with the tip cut off), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. A support was used to keep the tools in a vertical position during the treatment, but the through holes allow direct contact of the tools with the sample holder (cathode).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eConventional nitriding was carried out using a direct current source with a capacity of up to 1200 V. The treatment temperatures were 300\u0026deg;C, 350\u0026deg;C and 400\u0026deg;C, the lowest values when compared to previous works of M2 steel nitriding [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] are due to the large length of the samples and the temperature gradient established during conventional nitriding [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. As demonstrated in Serra et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], the recorded temperatures are measured at the base of the tools, if they could be measured at the tips they would be much higher.\u003c/p\u003e \u003cp\u003eAll treatments were preceded by a pre-sputtering with hydrogen atmosphere at 300\u0026deg;C, time of 1 hour and pressure of 8.0‧10\u003csup\u003e2\u003c/sup\u003e Pa. Then the atmosphere was changed to a mixture of hydrogen and nitrogen (H2:N2\u0026thinsp;=\u0026thinsp;64 sccm:6 sccm) and the voltage was adjusted until the treatment temperature was reached. The composition of the atmosphere was chosen so that it did not exceed 10% nitrogen, so as to inhibit the formation of the compound layer and favor the formation of a more stable layer for application in the tools [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Previous studies have shown that a high thickness compounds layer makes the surface brittle [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] which may contribute to the increased possibility of cutting edge breakage or layer detachment. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes the treatment conditions applied to each sample and the nomenclature used for each sample.\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\u003eNomenclature of samples and their respective treatment parameters used\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"8\" nameend=\"c9\" namest=\"c2\"\u003e \u003cp\u003eTreatment Conditions\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003ePre-Sputtering\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e \u003cp\u003eSputtering\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTemperature (\u0026deg;C)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePressure (Pa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTime (h)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eGases H\u003csub\u003e2\u003c/sub\u003e (sccm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTemperature (\u0026deg;C)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePressure (Pa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eTime (h)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eGases H\u003csub\u003e2\u003c/sub\u003e: N\u003csub\u003e2\u003c/sub\u003e (sccm)\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\u003eUT\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\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\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN300\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8,0 10\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1,0 10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64:6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN350\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8,0 10\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e350\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1,0 10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64:6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN400\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8,0 10\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1,0 10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e64:6\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\u003eThe tools that had the tip previously cut were separated for characterization, where a transverse cut was made to separate the upper part, reducing the size of the sample and facilitating its handling. A sample relative to each treatment condition was embedded in bakelite with the lateral surface facing down and then sanded using 80, 220, 360, 400, 600 and 1200 mesh sandpaper. After sanding, the samples were polished on a felt disc using alumina with a granulometry of 3 \u0026micro;m. Cross-sectional samples were used to obtain Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) images of the cross-sectional surface and for Vickers microhardness (HV) measurements used in the profile. The other samples were used for XRD characterization, to obtain surface morphology images, and for surface roughness and microhardness measurements.\u003c/p\u003e \u003cp\u003eX-ray diffraction (XRD) was performed using a XRD-6000 Shimadzu diffractometer operating at 40 kV and 30 mA, Cu-Kα radiation with λ\u0026thinsp;=\u0026thinsp;0.154060 nm and with a range of 35\u0026deg; to 105\u0026deg;. Rietveld analysis was performed using the ReX Powder Diffraction software (version 9.2). The morphological aspects of the surface and the thickness and uniformity of the compounds layer were observed in a Scanning Electron Microscope (SEM) from FEI Company, model Quanta TM 250-FEG. Before being taken to the SEM, the transverse samples were chemically attacked by immersion in a 4% Nital solution (4% nitric acid and 96% ethyl alcohol) for a time between 5 and 7 seconds. The thickness and uniformity of the diffusion zone was observed using an Olympus optical microscope, model CX31.\u003c/p\u003e \u003cp\u003eThe surface microhardness and microhardness profile were evaluated using an Insize microdurometer, model ISH-TDV 100. For surface microhardness, the measurement was repeated 5 times using a load of 0.05 kgf and an indentation time of 15 s. For the measurements used in the profile, the same load conditions and indentation time were maintained, measurements being taken every 5 \u0026micro;m perpendicular to the surface up to a depth of 80 \u0026micro;m. At each measurement, the indenter was laterally displaced 15 \u0026micro;m to avoid the influence of previous indentations, and for a distance of 0 \u0026micro;m, the microhardness value obtained for the surface was considered. The average roughness (Ra) measurements were made with the aid of a SJ210 Mitutoyo rugosimeter, respecting the provisions of NBRISO4288 [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe performance simulation of the tools was carried out in a CNC machining center. The machined material was SAE 1045 steel due to its wide use in the metalworking industry and low cost [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Machining planning was carried out in such a way as to allow the machining of the maximum number of holes in a specimen, respecting the minimum distance between holes and between holes and the edge of the specimens. According to Rodrigues et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], this distance is 1.5 times the diameter of the holes. Thus, it was established that a maximum of 14 holes would be machined in each block. It was established that the machined holes would be non-through holes, \u0026ldquo;blind holes\u0026rdquo;. Four stopping criteria (end of life) were adopted: complete tool failure (breakage, including edge chipping), excessive occurrence of noise, the maximum number of 14 holes (1 block) and the maximum flank wear (VB\u003csub\u003em\u0026aacute;x\u003c/sub\u003e) of 0.5 mm.\u003c/p\u003e \u003cp\u003eThe cutting parameters used for drilling were defined based on technical catalogs [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] that recommend a cutting speed of 20 m/min (rotation of 796 RPM) and feed of 0.19 mm/rev (151 mm/min) for high-strength carbon steel machining (above 27 HRC), these parameters were adjusted in a pre-test using an untreated drill and tape-shaped chip formation was verified, the cutting speed was increased until the chip size was adjusted and the feed per revolution was decreased. After adjustment, the cutting speed was fixed at 35 m/min (1393 RPM) and the feed per revolution at 0.04 mm/rev (50 mm/min). The depth of the holes was 20 mm, using intermittent feed (woodpecker feed) to help the chip removal and contribute to the machining of holes with good dimensional quality [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. An OSFL (One-Step Feed-Length) feed of 5 mm was adopted for each step.\u003c/p\u003e \u003cp\u003eThe measurement of the progressive wear of the tools was done by image, with the ImageJ software that allows the conversion of pixels into millimeters. Images were acquired every 2 complete holes (defined as a machining cycle) using a portable microscope coupled to the machine table, which eliminated the need to remove the tool at the end of each cycle and ensured the same approximation between the tool and the microscope in each capture. This approximation was made within the machining program.\u003c/p\u003e \u003cp\u003eThe RMS electric current was monitored by a system formed by three hall effect sensors, model SCT-013-000, with a range from 0 to 100 mA, a data acquisition board mounted with voltage divider resistors, load resistor, filter capacitor and an Atmega 2560 microcontroller. The values were obtained for each machining cycle (2 holes). The graphical pattern obtained for the useful machining cycle (cutting motion and approximation/retreat motion) is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Note that the cycle alternates between cut and retreat/approximation motions, which is characteristic of the intermittent cutting cycle. After data acquisition, data referring only to the cutting motion (which can be directly associated with the performance of the tools) were separated, and the initial and final values of each cutting subcycle were removed, thus avoiding the influence of the approximation/retreat motion, and the average for each tool was calculated.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe dimensional tolerance of the holes was evaluated using the ImageJ software to convert pixels into mm and then transferring the images to the AutoCAD software (version 2022) from AutoDesk, applying a scale factor and using the 3-points-circle and diameter-dimension functions. Five measurements were made for each hole. According to the tool manufacturer Dormer [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] the tolerance for general drilling is H12. Thus, the minimum and maximum dimensions of the holes must be, respectively, 8.000 mm and 8.150 mm. The surface roughness of the holes was evaluated by measures of average roughness (Ra) made with the aid of a SJ210 Mitutoyo rugosimeter and in accordance with the NBRISO4288 [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In each hole, 20 measurements were taken, varying the position of the probe by 90\u0026deg; every 5 measurements.\u003c/p\u003e"},{"header":"3 Results and Discussion","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3.1 XRD Analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the XRD patterns obtained for the untreated and treated samples, together with the results calculated by the Rietveld refinement application, including quantitative analysis of the phases obtained.\u003c/p\u003e \u003cp\u003eThe pattern obtained for the untreated sample, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, was related to a combination of 4 distinct phases recorded in the Inorganic Crystal Structure Database (ICSD) and used to determine the theoretical profile: iron (Fe) 64795 [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], iron-molybdenum (Mo\u003csub\u003e0.03\u003c/sub\u003eFe\u003csub\u003e0.97\u003c/sub\u003e) 632630 [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], carbides M type (M\u003csub\u003e6\u003c/sub\u003eC) 672333 [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], chromium carbide (Cr\u003csub\u003e23\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003e) 2837 [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe pattern obtained for the untreated sample, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, was related to a combination of 4 distinct phases recorded in the Inorganic Crystal Structure Database (ICSD) and used to determine the theoretical profile: iron (Fe) 64795 [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], iron-molybdenum (Mo\u003csub\u003e0.03\u003c/sub\u003eFe\u003csub\u003e0.97\u003c/sub\u003e) 632630 [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], carbides M type (M\u003csub\u003e6\u003c/sub\u003eC) 672333 [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], chromium carbide (Cr\u003csub\u003e23\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003e) 2837 [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThese phases agree with the composition typically suggested for M2 high-speed steel and show the predominance of a Mo\u003csub\u003e0.03\u003c/sub\u003eFe\u003csub\u003e0.97\u003c/sub\u003e phase, which corresponds to a solid solution of molybdenum in iron, and can be observed a considerable amount of carbide type Cr\u003csub\u003e23\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003e and type M\u003csub\u003e6\u003c/sub\u003eC. The GOF (Goodness-Of-Fit) adjustment parameter equal to 1.33 obtained in the refinement, together with the visual adjustment between the experimental (green) and calculated (red) profiles, confirm the agreement with the reported phases [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFor the three treatment conditions, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb-d, in addition to the four phases observed for the untreated sample (UT), two more phases were identified, also registered in the Inorganic Crystal Structure Database (ICSD) and added to the first four for the determination of the theoretical profile: expanded austenite (S) (FeN\u003csub\u003e0,095\u003c/sub\u003e) 31908 [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] and iron nitride Fe\u003csub\u003e4\u003c/sub\u003eN 60195 (JACK, 1948). The predominance of the Mo0.03Fe0.97 phase, as observed for the untreated sample, is due to the great influence of the substrate on the measurements. The GOF values obtained for the three samples (1.17; 1.16 and 1.14; for N300, N350 and N400, respectively) indicate a good agreement between the experimental profile and the associated phases [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The percentages presented indicate a growth of the diffusion zone when the treatment temperature is increased from 300\u0026deg;C to 350\u0026deg;C, evidenced by the greater amount of S phase. This behavior is the most common and it was observed in other works such as that of Abreu et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. On the other hand, the unusual behavior of diffusion zone reduction with the increase in temperature, presented by the sample treated at 400\u0026deg;C, can be explained by the greater amount of Fe\u003csub\u003e4\u003c/sub\u003eN phase and by the higher volume of Cr\u003csub\u003e23\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003e precipitates. Young et al. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] also reported the formation of these precipitates in the austenitic stainless steel nitriding with an atmosphere of N\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e. The presence of these carbides, as well as higher levels of the Fe\u003csub\u003e4\u003c/sub\u003eN phase, act as barriers to nitrogen diffusion [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Optical microscopy and scanning electron microscopy analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the surface morphology of an untreated sample and samples after nitriding at different temperatures.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor the untreated sample, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, a more uniform surface can be observed only with the presence of some regions that can be associated with metallic inclusions. For the treated samples, a surface with a more heterogeneous morphology can be observed, again characterized by the presence of inclusions and precipitates in greater volume. These precipitates can be associated with the presence of chromium carbides shown in the XRD results, section \u003cspan refid=\"Sec4\" class=\"InternalRef\"\u003e3.1\u003c/span\u003e, and they were also observed in the work by Li et al. [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. The increase in the volume of precipitates on the surface of the treated samples agrees with the greater volume of Cr\u003csub\u003e23\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003e phase, also shown in the XRD results and it is related to the decarburization caused by the addition of nitrogen, the carbon diffuses in the opposite direction to the nitrogen and it is free to combine with elements such as iron and chromium. The presence of carbides on the surface is an indication of the non-formation of a compounds layer, as otherwise they would occupy the interface between this layer and the diffusion zone [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. A more irregular surface can also be observed for the sample treated at a temperature of 400\u0026deg;C, evidenced here by the defects indicated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed by indications in blue. This behavior may be associated with the increase in sputtering intensity with increasing temperature. Works such as that of Morgiel et al. [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] showed a similar variation.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the optical microscopy of the nitrided samples, highlighting the formation of the diffusion zone for all treatment conditions applied, which portrays the efficiency of the treatment even with nitriding time of only 2 h.\u003c/p\u003e \u003cp\u003eComparing the results shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea and Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb, an increase in the average thickness of the diffusion zone from 24.09 \u0026micro;m to 28.59 \u0026micro;m was observed with the increase in temperature from 300\u0026deg;C to 350\u0026deg;C, this behavior is the most expected with temperature variation and it was observed in other works [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. With the increase in temperature to 400\u0026deg;C, the diffusion zone presented only 21.57 \u0026micro;m even with the increase in temperature, which confirms the behavior suggested by the smaller volume of S phase presented in the XRD results and once again can be related to the greater volume of the Cr\u003csub\u003e23\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003e and Fe\u003csub\u003e4\u003c/sub\u003eN phases that act as barriers to nitrogen diffusion [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e shows the cross-section surface images of the samples obtained by SEM. All samples have a martensitic microstructure, characterized by the needles highlighted in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, as a result of the quenching treatment applied by the manufacturer. It can be observed in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb-c that none of the treated samples formed a compounds layer, showing the efficiency of the treatment parameters defined in the formation of a nitrided layer consisting only of a diffusion zone. Thus, the Fe\u003csub\u003e4\u003c/sub\u003eN iron nitride presented in the XRD results can be associated only with the precipitation of nitrides in the form of needles within the diffusion zone and this corroborates with the results presented by Danelon et al. [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Visually, it is possible to observe a greater density of needles in the nitrided samples, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb-d, in relation to the untreated sample, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea, mainly for the nitrided sample at 400\u0026deg;C, this is due to the combined presence of martensite needles and Fe\u003csub\u003e4\u003c/sub\u003eN in the diffusion zone and it is in agreement with the results presented in section \u003cspan refid=\"Sec4\" class=\"InternalRef\"\u003e3.1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Vickers Surface Microhardness and Vickers Microhardness Profile\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e presents the Vickers surface microhardness results for the untreated sample (UT) and for the treated samples. It is initially observed that all treatment conditions applied here contributed to the increase in surface microhardness, with the highest result presented by the N400 sample, which exceeded by 1.95 times the average value presented by the UT sample. The increasing behavior of surface microhardness with treatment temperature can be associated initially with the combined effect of the increase in the diffusion zone thickness and the content of Fe\u003csub\u003e4\u003c/sub\u003eN, when the temperature is increased from 300\u0026deg;C to 350\u0026deg;C. When the temperature is increased from 350\u0026deg;C to 400\u0026deg;C, although a reduction in the thickness of the diffusion zone is presented, the Fe\u003csub\u003e4\u003c/sub\u003eN content was still increasing and it was evidenced both quantitatively in section \u003cspan refid=\"Sec4\" class=\"InternalRef\"\u003e3.1\u003c/span\u003e and qualitatively in section \u003cspan refid=\"Sec5\" class=\"InternalRef\"\u003e3.2\u003c/span\u003e and justifies this increase.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e shows the Vickers microhardness profiles obtained from measurements made in the cross-section of the samples. The horizontal line (dashed red) shows the NHT value (from German, \u003cb\u003en\u003c/b\u003eitrier\u003cb\u003eh\u003c/b\u003e\u0026auml;rte\u003cb\u003et\u003c/b\u003eiefand \u0026ndash; nitriding depth) which corresponds, according to DIN 50190 standard (DEUTSCHES INSTITUT F\u0026Uuml;R NORMUNG, 1979) to a minimum gain of 50 HV above the core hardness value.\u003c/p\u003e \u003cp\u003eFor the untreated sample, a profile is observed in which the values are close to the average microhardness value of the substrate. In the treated samples, it can be seen that the surface microhardness gradually decreases from the surface microhardness until it assumes values comparable to that of the core. N400 sample, although presenting a higher value for surface microhardness, has a more vertical profile than samples N300 and N350, which represents a more abrupt hardness reduction, due to this behavior, it can be noted that the calculated value for NHT is reached at a lower depth (38\u0026micro;m). Applying the method to the N300 and N350 samples, we obtained diffusion zone thicknesses equal to 45\u0026micro;m and 50 \u0026micro;m, respectively. The values obtained with the method described in DIN 50190 [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e] are generally higher than those obtained by optical microscopy images, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. However, they present the same behavior indicated both in the results of optical microscopy and by the quantitative analysis of the phases in the XRD data shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, confirming that initially there is a growth of the diffusion zone with the increase in the treatment temperature up to 350\u0026deg;C, followed by a reduction when the treatment temperature is 400\u0026deg;C.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Surface Roughness\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e presents the surface roughness results of the UT sample and the treated samples. The dashed horizontal lines show the limits of the surface roughness classes in which the samples fit according to the Associa\u0026ccedil;\u0026atilde;o Brasileira de Normas T\u0026eacute;cnicas [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e], which classifies the finishing of the samples according to 12 classes, from N1 to N12, where N1 represents the best state of surface finish and N12 the worst state of surface finish. All applied treatments caused an increase in surface roughness in relation to the untreated sample, this behavior is characteristic of conventional plasma nitriding and it is mainly due to surface sputtering and volumetric expansion of the network associated with nitrogen diffusion [\u003cspan additionalcitationids=\"CR44\" citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. The severity of sputtering grows with increasing treatment temperature [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e], which explains the increase in average surface roughness in the same direction. In treatments at lower temperatures, N300 and N350, the surface quality changes from N3 to N4, while for the N400 sample there is a gain of two roughness classes, from N3 to N5. Thus, considering only the roughness, it is expected that the samples treated at lower temperatures present more significant results in the face of abrasive wear operations.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Wear analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e shows the tool life curves obtained after the tool performance test. For all tools, the stopping criterion of the maximum number of holes (14 holes) prevailed, since none of the tools showed significant failure and did not even reach a maximum flank wear of 0.50 mm. The evolution of tool wear is similar to the classic wear curve (Lorentz), characterized by an initial zone with high wear rate (break-in period), followed by a zone with slow increase in the wear indicator (steady-state wear region) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe first significant difference in behavior with the treatments is observed for the N400 tool, the treatment resulted in an extension of the break-in phase to the sixth hole, which contributed to this tool presenting the highest flank wear in all measurement stops. The less noble behavior of the N400 sample can be associated with the increase in surface roughness, revealed by the results shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e. The work by Do Nascimento Rosa et al. [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e] showed a similar relation to this behavior. Additionally, this was the sample that presented the highest surface microhardness value (higher resistance to plastic deformation), which should contribute to a lower level of flattening on the surface and, consequently, to a higher coefficient of friction [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOn the other hand, the treatments applied at lower temperatures contributed to a reduction in the flank wear rate, especially after the sixth hole. The direct comparisons of the N300 and N350 curves with the UT curve in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e reveal a lower slope of the curves within the steady state, this shows a more efficient balance between the increases in surface microhardness and the consequent increase in roughness due to the characteristics of the process (sputtering). This result shows that the increase in surface roughness cannot be neglected compared to the increase in hardness obtained with nitriding and it reveals that treatments at lower temperatures result in a better balance between these properties.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Electric current\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e presents the average data of required current during the performance simulation. It is known that the consumed electrical power, as well as the consumed mechanical power, are proportional to the values of electric current required by the machine tool [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]. The data presented correspond only to the time intervals in which material removal actually occurred, see section 2.4. The results show higher efficiency of N300 and N350 samples. This behavior is in accordance with the one presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, since the machining strength increases with tool wear and it is also a consequence of the low roughness achieved even after treatment. Thus, it can be affirmed that the treatments, besides contributing to increase the wear resistance of the tools, contributed to a reduction in machining power. On the other hand, the N400 sample presented the highest average value of consumed current, agreeing with the results of surface roughness (directly related to friction) and reinforcing the negative effect of treatments at high temperatures.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.7 Holes measurement (Dimensional Tolerance)\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e presents the values of the holes diameters measures, together with the maximum and minimum diameters established by the ASSOCIA\u0026Ccedil;\u0026Atilde;O BRASILEIRA DE NORMAS T\u0026Eacute;CNICAS ( 1995) for the dimensional tolerance 8H12, defined for drilling operations in general. Only one of the holes in the untreated sample, Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003ea, was outside the dimensional tolerance (hole 2), representing a process failure that corresponds to 7.14% of the performed holes. All the treated tools produced holes within the diameter range established by the 8H12 dimensional tolerance, allowing to ensure the good dimensional quality of the holes machined with the treated tools, including those performed by the N400 drill, which showed the highest level of wear, but still lower than the maximum flank wear of 0.50 mm defined as stopping criterion. This result contributes to reinforce that none of the tools reached the end of tool life and, above all, proves the ability of the tools to machine dry holes within the required dimensional quality.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.8 Hole roughness\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e presents the results of average surface roughness (Ra) of the machined holes. Figure\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ea-c show the comparison of the results obtained for each treated tool with those obtained for the untreated tool. Figure\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ed shows the direct comparison between those that presented the best surface quality, N300 and N350. All the holes presented surface quality N9 and no change in roughness class could be observed with the treatments, however a change to lower values can be observed when the holes were machined with the N350 tool and especially when using the N300 tool, Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003eb and Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ea, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ed reinforces the obtaining of holes with lower average roughness for treatments at lower temperatures. This result shows a relation between the tools roughness, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, and the holes roughness, so that tools with lower roughness tend to produce holes with lower surface roughness, this behavior is related to the ease of chip disposal provided by less rough surfaces, which is even more important in dry machining, since one of the most important functions of the cutting fluid is to assist in chip disposal. The N400 sample, Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ec, although presenting higher average surface roughness than the UT sample, had holes with equivalent roughness values, this result does not compare the relation presented, since nitriding modifies the surface of the tools contributing to a lower coefficient of friction for the same roughness level.\u003c/p\u003e \u003c/div\u003e"},{"header":"4 Conclusions","content":"\u003cp\u003eCross-section images confirmed the formation of the nitrided layer after 2 hours of treatment. The layer was formed only by a diffusion zone, showing the efficiency of the chosen parameters in inhibiting the growth of a brittle compound layer. The data obtained from Rietveld refinement confirmed this formation and the other conclusions are summarized below:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eAll treatments resulted in an increase on surface microhardness and in the formation of a hardness gradient from the surface to the center, which contributed to greater stability of the nitrided layers.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eAn increase in surface roughness was observed for all samples, an expected behavior due to surface sputtering. In the sample treated at 400\u0026deg;C, the value observed for the average roughness was much higher than that presented by the other samples.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe tool life curves revealed that the treatment at 400\u0026deg;C prolonged the break-in phase and resulted in the condition with the highest flank wear, this behavior was associated with a considerable increase in roughness. The treatments at lower temperatures, on the other hand, contributed to the reduction in the wear rate within the steady-state.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe results of electric current showed that machining with the tool treated at 400\u0026deg;C showed higher current values, suggesting higher consumed power.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eAll treated tools machined holes respecting the 8H12 dimensional tolerance defined for general drilling operations. This behavior was better than that of the untreated sample, which had one of the holes with a dimension greater than that defined by the tolerance limit. Regarding surface quality, the tools with lower roughness also produced holes with lower roughness.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was financial support was provided by National Council for Scientific and Technological Development.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest/Competing interests\u003c/strong\u003e\u003c/p\u003e\n\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\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePetteson Linniker Carvalho Serra:\u003c/strong\u003e Methodology, Formal analysis, Data curation, Writing - Original draft Writing-Review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eWeslley Rick Viana Sampaio:\u003c/strong\u003e Formal analysis, Writing-Review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatrick Abreu de Oliveira:\u003c/strong\u003e Methodology, Formal analysis, Data curation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRenan Matos Mon\u0026ccedil;\u0026atilde;o:\u003c/strong\u003e Methodology, Formal analysis, Data curation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eJos\u0026eacute; Ribamar do Carmo Pereira J\u0026uacute;nior:\u003c/strong\u003e Methodology, Formal analysis, Data curation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePaulo Roberto Queiroz de Almeida:\u003c/strong\u003e Methodology, Formal analysis, Data curation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eWenio Fhara Alencar Borges:\u003c/strong\u003e Methodology, Formal analysis, Writing-Review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTh\u0026eacute;rcio Henrique de Carvalho Costa:\u003c/strong\u003e Conceptualization, Resources, Analysis formal, Writing-Review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMarcos Guilherme Carvalho Braulio Barbosa:\u003c/strong\u003e Analysis formal, Resources, Data curation, Analysis formal, Writing-Review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eR\u0026ocirc;mulo Ribeiro Magalh\u0026atilde;es de Sousa:\u003c/strong\u003e Conceptualization, Methodology, Resources, Analysis formal, Supervision, Funding acquisition, Writing-Review \u0026amp; editing.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eShi C, Yu A, Wu J, et al (2017) Study on position of laser cladded chip breaking dot on rake face of HSS turning tool. 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Mater Charact 184:111662. https://doi.org/10.1016/j.matchar.2021.111662\u003c/li\u003e\n\u003cli\u003eLi G, Liang Y, Sun H, et al (2020) Effect of pre-existing carbides prepared by different heat treatments on the nitriding behaviour during a carburizing and nitriding duplex treatment of an M50NiL steel. Surf Coatings Technol 395:125930. https://doi.org/10.1016/j.surfcoat.2020.125930\u003c/li\u003e\n\u003cli\u003eJegou S, Barrallier L, Kubler R (2010) Phase transformations and induced volume changes in a nitrided ternary Fe\u0026ndash;3%Cr\u0026ndash;0.345%C alloy. Acta Mater 58:2666\u0026ndash;2676. https://doi.org/10.1016/j.actamat.2009.12.053\u003c/li\u003e\n\u003cli\u003eMorgiel J, Maj Ł, Szymkiewicz K, et al (2022) Surface roughening of Ti-6Al-7Nb alloy plasma nitrided at cathode potential. Appl Surf Sci 574:151639. https://doi.org/10.1016/j.apsusc.2021.151639\u003c/li\u003e\n\u003cli\u003eDanelon MR, Soares F, Manfrinato MD, Rossino LS (2020) Estudo do efeito da nitreta\u0026ccedil;\u0026atilde;o i\u0026ocirc;nica a plasma na resist\u0026ecirc;ncia ao desgaste do a\u0026ccedil;o SAE 1020 utilizado em matriz de conforma\u0026ccedil;\u0026atilde;o. Rev Bras Apl V\u0026aacute;cuo 39:142. https://doi.org/10.17563/rbav.v39i2.1166\u003c/li\u003e\n\u003cli\u003eDEUTSCHES INSTITUT F\u0026Uuml;R NORMUNG (1979) DIN 50190: Hardness depth of heat-treated parts; determination of the effective depth of hardening after flame or induction hardening\u003c/li\u003e\n\u003cli\u003eASSOCIA\u0026Ccedil;\u0026Atilde;O BRASILEIRA DE NORMAS T\u0026Eacute;CNICAS (1984) NBR 8404: Indica\u0026ccedil;\u0026atilde;o do estado de superf\u0026iacute;cies em desenhos t\u0026eacute;cnicos\u003c/li\u003e\n\u003cli\u003eSingh GP, Alphonsa J, Barhai PK, et al (2006) Effect of surface roughness on the properties of the layer formed on AISI 304 stainless steel after plasma nitriding. Surf Coatings Technol 200:5807\u0026ndash;5811. https://doi.org/10.1016/j.surfcoat.2005.08.149\u003c/li\u003e\n\u003cli\u003eAkbari A, Mohammadzadeh R, Templier C, Riviere JP (2010) Effect of the initial microstructure on the plasma nitriding behavior of AISI M2 high speed steel. 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Tribol Int 93:614\u0026ndash;619. https://doi.org/10.1016/j.triboint.2015.01.003\u003c/li\u003e\n\u003cli\u003eBarbosa MGCB, Hassui A, de Oliveira PA (2021) Effect of cutting parameters and cutting edge preparation on milling of VP20TS steel. Int J Adv Manuf Technol 116:2929\u0026ndash;2942. https://doi.org/10.1007/s00170-021-07654-7\u003c/li\u003e\n\u003cli\u003eFerraresi D (1970) Fundamentos da Usinagem dos Metais, 1st ed. S\u0026atilde;o Paulo\u003c/li\u003e\n\u003cli\u003eASSOCIA\u0026Ccedil;\u0026Atilde;O BRASILEIRA DE NORMAS T\u0026Eacute;CNICAS (1995) NBR 6158: Sistema de toler\u0026acirc;ncias e ajustes. Rio de Janeiro, p 79\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"High-speed steel, plasma nitriding, roughness, drilling, dry machining","lastPublishedDoi":"10.21203/rs.3.rs-6490563/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6490563/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHigh-speed steel is one of the most widely used materials in machining tools. However, applications such as dry machining require superior properties to those presented by conventional tools. Surface treatments such as plasma nitriding are alternatives to improve these properties. This work proposes a study of the application of plasma nitriding with lower temperatures and times (300\u0026deg;C, 350\u0026deg;C and 400\u0026deg;C, for 2 hours) on high-speed steel tools to be evaluated in dry drilling process. The samples were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction with application of Rietveld routine, surface microhardness, microhardness profile and average surface roughness (Ra) measurements. Then, the tools were submitted to performance simulation in a CNC machining center and analyzed based on measurements of the flank wear evolution, the required electric current by the machine during cutting times and by the diameter and surface roughness of the machined holes. The results showed an increase in flank wear with the treatment at 400\u0026deg;C due to the higher surface roughness, while the tools treated at lower temperatures showed better performance than the untreated tool, evidenced by the lower wear rate in the steady state, by machining all holes within tolerance limits and by the lower surface roughness of the holes. It was observed, thus, that treatments at lower temperatures produce conditions of greater balance between hardness and surface roughness, contributing to higher wear resistance.\u003c/p\u003e","manuscriptTitle":"Study of the plasma nitriding effect on high-speed steel drills: performance in dry machining","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-13 12:01:36","doi":"10.21203/rs.3.rs-6490563/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Minor Revisions Needed","date":"2025-07-01T09:10:45+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-05-08T13:34:05+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-08T12:04:22+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-08T06:20:15+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Advanced Manufacturing Technology","date":"2025-05-05T22:26:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-advanced-manufacturing-technology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jamt","sideBox":"Learn more about [The International Journal of Advanced Manufacturing Technology](https://www.springer.com/journal/170)","snPcode":"170","submissionUrl":"https://submission.nature.com/new-submission/170/3","title":"The International Journal of Advanced Manufacturing Technology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"760096e4-1959-41df-960f-de059ac5ccb5","owner":[],"postedDate":"May 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-07-17T12:50:44+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-13 12:01:36","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6490563","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6490563","identity":"rs-6490563","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}