Articles de revues : « S-phase, stainless steel, nitriding, carburising »

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Karadas, Riza, Ozgur Celik et Huseyin Cimenoglu. « Low Temperature Nitriding of a Martensitic Stainless Steel ». Defect and Diffusion Forum 312-315 (avril 2011) : 994–99. http://dx.doi.org/10.4028/www.scientific.net/ddf.312-315.994.

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Nitriding is as an effective technique applied for many years to improve the surface hardness and wear resistance of low carbon and tool steels [1]. In the case of stainless steels, increase of surface hardness and wear resistance accompany by a drop in corrosion resistance due to the precipitation of CrN. In this respect, many attempts have been made to modify the surfaces of austenitic stainless steels to increase their surface hardness and wear resistance without scarifying the corrosion resistance [2-6]. It is finally concluded that, nitriding at temperatures lower than conventional nitriding process (which is generally about 550°C) has potentiality to produce a nitrogen expanded austenite (also known as S-phase), on the surface without formation of CrN. Due to the superb properties of the S-phase, the low temperature nitrided austenitic stainless steels exhibit very high surface hardness, a good wear resistance, and more importantly, an excellent corrosion resistance. Recently some attempts have been made to apply low temperature nitriding to martensitic stainless steels, which are widely used in the industries of medicine, food, mold and other civil areas [7-9]. In these works, where nitriding has been conducted by plasma processes, superior surface hardness, along with excellent wear and corrosion resistances have been reported for AISI 410 and AISI 420 grade martensitic stainless steels. This work focuses on low temperature gas nitriding of AISI 420 grade martensitic stainless steel in a fluidized bed reactor. In this respect the microstructures, phase compositions, hardness, wear and corrosion behaviours of the original and nitrided martensitic stainless steels have been compared.

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Nishimoto, Akio, et Katsuya Akamatsu. « Effect of Pre-Deforming on Plasma Nitriding Response of 304 Stainless Steel ». Materials Science Forum 654-656 (juin 2010) : 1811–14. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1811.

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The effect of a modified layer caused by pre-deforming on the low temperature plasma nitriding of AISI 304 austenitic stainless steel was investigated. The aim of using the deformed layer is to produce a thicker nitrided layer and to decrease the nitriding temperature due to the much faster diffusion of nitrogen. The pre-deformed sample was prepared by the rolling in 0, 1, 2, 3, and 4% ratios. Plasma nitriding was carried out at 673 and 723 K for 18 ks under 600 Pa pressures in presence of N2/H2 in 50:50 ratio. The microhardness, thickness and phase composition of nitrided layers formed on the surface of pre-deformed and non-deformed samples were investigated using Vickers microhardness tester, optical microscope and X-ray diffraction techniques, respectively. After nitriding, maximum hardness ~1150 HV was achieved on the pre-deformed sample. XRD pattern showed that most dominant phase of the nitrided layer consisted of the expanded austenite (S phase). In addition, the pre-deforming by rolling had a significant influence on the hardness and thickness of the S phase. That is, the hardness and thickness of the S phase were increased by applying the pre-deformation.

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Haruman, E., Y. Sun, H. Malik, Agus Geter E. Sutjipto, S. Mridha et K. Widi. « Low Temperature Fluidized Bed Nitriding of Austenitic Stainless Steel ». Solid State Phenomena 118 (décembre 2006) : 125–30. http://dx.doi.org/10.4028/www.scientific.net/ssp.118.125.

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In the present investigation, low temperature nitriding has been attempted on AISI 316L austenitic stainless steel by using a laboratory fluidized bed furnace. The nitriding was performed in temperature range between 400°C and 500°C. X-ray diffraction, metallography, and corrosion tests were used to characterize the resultant nitrided surface and layers. The results showed that fluidized bed process can be used to produce a precipitation-free nitrided layer characterized by the S phase or expanded austenite on austenitic stainless steel at temperatures below 500°C. But there exists a critical temperature and an incubation time for effective nitriding, below which nitriding is ineffective. The corrosion behaviour of the as-nitrided surfaces is significantly different from that previously reported for low temperature plasma nitriding. This anomaly is explained by the formation of iron oxide products and surface contamination during the fluidized process.

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Adachi, Shinichiro, Motoo Egawa, Takuto Yamaguchi et Nobuhiro Ueda. « Low-Temperature Plasma Nitriding for Austenitic Stainless Steel Layers with Various Nickel Contents Fabricated via Direct Laser Metal Deposition ». Coatings 10, n^o 4 (7 avril 2020) : 365. http://dx.doi.org/10.3390/coatings10040365.

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In this study, low-temperature plasma nitriding is applied to austenitic stainless steels at temperatures below 450 °C. This enhances the wear resistance of the steels with maintaining corrosion resistance, by producing expanded austenite (known as the S-phase), which dissolves excessive nitrogen. Austenitic stainless steels contain nickel, which has the potential to play an important role in the formation and properties of the S-phase. In this experiment, austenitic stainless steel layers with different nickel contents were processed using direct laser metal deposition, and subsequently treated using low-temperature plasma nitriding. As a result, the stainless steel layers with high nickel contents formed the S-phase, similar to the AISI 316L stainless steel. The thickness and Vickers hardness of the S-phase layers varied with respect to the nickel contents. Due to lesser chromium atoms binding to nitrogen, the chromium content relatively decreased. Moreover, there was no evident change in the wear and corrosion resistances due to the nickel contents.

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GHELLOUDJ, Elhadj. « MICROSTRUCTURE, MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF AISI 316L STAINLESS STEEL DURING SALT BATH NITRIDING ». Acta Metallurgica Slovaca 27, n^o 2 (1 juin 2021) : 47–52. http://dx.doi.org/10.36547/ams.27.2.952.

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The aim of the current work was to analyse the impact of salt bath nitriding on the behavior of the tribological characteristics and surface microstructures of AISI 316L stainless steels. Nitriding was carried out at 580°C for 10 h. The tribological, structural behavior of the AISI 316L before and after salt bath nitriding was compared. The surface microstructures, tribological characteristics, as well as its surface hardness, were investigated using optical microscopy (OM), X-ray diffractometer (XRD), surface profilometer, pin-on-disk wear tester and microhardness tester. In the current work the experimental results showed that a great surface hardness could be achievable through salt bath nitriding technique because of the formation of the so-called expanded Austenite (S-phase), the nitrogen diffusion region. The surface hardness of AISI 316 stainless steel after nitriding process reached 1100 HV0.025 which was six times the untreated sample hardness. The S-phase is additionally expected to the improvement of wear resistance and decrease the friction coefficient.

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Adachi, Shinichiro, Takuto Yamaguchi et Nobuhiro Ueda. « Formation and Properties of Nitrocarburizing S-Phase on AISI 316L Stainless Steel-Based WC Composite Layers by Low-Temperature Plasma Nitriding ». Metals 11, n^o 10 (27 septembre 2021) : 1538. http://dx.doi.org/10.3390/met11101538.

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Stainless steel-based WC composite layers fabricated by a laser cladding technique, have strong mechanical strength. However, the wear resistance of WC composite layers is not sufficient for use in severe friction and wear environments, and the corrosion resistance is significantly reduced by the formation of secondary carbides. Low-temperature plasma nitriding and carburizing of austenitic stainless steels, treated at temperatures of less than 450 °C, can produce a supersaturated solid solution of nitrogen or carbon, known as the S-phase. The combined treatment of nitriding and carburizing can form a nitrocarburizing S-phase, which is characterized by a thick layer and superior cross-sectional hardness distribution. During the laser cladding process, free carbon was produced by the decomposition of WC particles. To achieve excellent wear and corrosion resistance, we attempted to use this free carbon to form a nitrocarburizing S-phase on AISI 316 L stainless steel-based WC composite layers by plasma nitriding alone. As a result, the thick nitrocarburizing S-phase was formed. The Vickers hardness of the S-phase ranged from 1200 to 1400 HV, and the hardness depth distribution became smoother. The corrosion resistance was also improved through increasing the pitting resistance equivalent numbers due to the nitrogen that dissolved in the AISI 316 L steel matrix.

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Adachi, Shinichiro, et Nobuhiro Ueda. « Wear and Corrosion Properties of Cold-Sprayed AISI 316L Coatings Treated by Combined Plasma Carburizing and Nitriding at Low Temperature ». Coatings 8, n^o 12 (10 décembre 2018) : 456. http://dx.doi.org/10.3390/coatings8120456.

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Cold-sprayed AISI 316L stainless steel coatings are treated to form an austenite phase with excessive dissolved nitrogen (known as the S-phase) by plasma nitriding at temperatures below 450 °C. The S-phase is a hard and wear-resistant layer with high corrosion resistance. However, the S-phase layer formed after only nitriding is thin and the hardness abruptly decreases at a certain depth; it lacks mechanical reliability. We examined two types of combined low-temperature plasma treatment to enhance the mechanical reliability of the S-phase layer: (i) sequential and (ii) simultaneous. In the sequential plasma treatment, the carburizing step was followed by nitriding. In the simultaneous treatment, the nitriding and carburizing steps were conducted at the same time. Both combined plasma treatments succeeded in thickening the S-phase layers and changed the hardness depth profiles to decrease smoothly. In addition, anodic polarization measurements indicated that sequential treatment involving carburizing followed by nitriding for 2 h each resulted in high corrosion resistance.

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Sumiya, Kenzo, Shinkichi Tokuyama, Akio Nishimoto, Junichi Fukui et Atsushi Nishiyama. « Application of Active-Screen Plasma Nitriding to an Austenitic Stainless Steel Small-Diameter Thin Pipe ». Metals 11, n^o 2 (22 février 2021) : 366. http://dx.doi.org/10.3390/met11020366.

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Low-temperature active-screen plasma nitriding (ASPN) was applied in this study to improve the bending rigidity and corrosion resistance of a small-diameter thin pipe composed of austenitic stainless steel (SUS 304). The inner and outer diameters of the pipe were ϕ0.3 and ϕ0.4 mm, respectively, and the pipe length was 50 mm. The jig temperature was measured using a thermocouple and was adopted as the nitriding temperature because measuring the temperature of a small-diameter pipe is difficult. The nitriding temperature was varied from 578 to 638 K to investigate the effect of temperature on the nitriding layer and mechanical property. The nitriding layer thickness increased with an increase in nitriding temperature, reaching 15 μm at 638 K. The existence of expanded austenite (S phase) in this nitriding layer was revealed using the X-ray diffraction pattern. Moreover, the surface hardness increased with the nitriding temperature and took a maximum value of 1100 HV above 598 K. The bending load increased with an increase in the nitriding temperature in relation to the thicker nitriding layer and increased surface hardness. The nitrided samples did not corrode near the center, and corrosion was noted only near the tip at high nitriding temperatures of 618 and 638 K in a salt spray test. These results indicated that the bending rigidity of the small-diameter thin pipe composed of austenitic stainless steel was successfully improved using low-temperature ASPN while ensuring corrosion resistance.

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Gołębiowski, Bartosz, et Wiesław Świątnicki. « Microstructural Changes Induced during Hydrogen Charging Process in Stainless Steels with and without Nitrided Layers ». Solid State Phenomena 186 (mars 2012) : 305–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.186.305.

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The purpose of this study is to analyze the effect of glow discharge nitriding on hydrogen degradation of two types of steels: two-phase austenitic-ferritic and single-phase austenitic. The nitriding process resulted in formation of surface layers composed of expanded austenite (S phase), and in the case of two-phase steel of expanded austenite and expanded ferrite. Microstructural changes occurring under the influence of hydrogen on steels without and with nitrided layers were investigated with the use of scanning (SEM) and transmission (TEM) electron microscopy techniques. It was shown that the density of cracks formed during cathodic hydrogen charging is higher on the surface of the non-nitrided steels compared to the nitrided steels after identical hydrogen charging process. Moreover in non nitrided steel hydrogenation leads to considerable increase of dislocation density, which results from the high concentration of hydrogen absorbed to the steel during its cathodic charging. This leads in turn to high stress concentration and local embrittlement giving rise to cracks formation. Conversely nitriding reduces the absorption of hydrogen and prevents structural changes resulting in hydrogen embrittlement. The conducted studies show that glow discharge nitriding can be used to increase resistance to hydrogen embrittlement of austenitic and austenitic ferritic stainless steels.

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GAO, YUXIN, et SHAOMEI ZHENG. « EFFECT OF PLASMA NITRIDING TEMPERATURES ON CHARACTERISTICS OF AISI 201 AUSTENITIC STAINLESS STEEL ». Surface Review and Letters 23, n^o 01 (février 2016) : 1550084. http://dx.doi.org/10.1142/s0218625x15500845.

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Samples of AISI 201 austenitic stainless steel were produced by plasma nitriding at 350[Formula: see text]C, 390[Formula: see text]C, 420[Formula: see text]C, 450[Formula: see text]C and 480[Formula: see text]C for 5[Formula: see text]h. Systematic characterization of the nitrided layer was carried out in terms of micrograph observations, phase identification, chemical composition depth profiling, surface microhardness measurements and electrochemical corrosion tests. The results show that the surface hardness and the layer thickness increased with increasing temperature. XRD indicated that a single S-phase layer was formed during low temperature ([Formula: see text][Formula: see text]420[Formula: see text]C), while Cr2N or CrN phase was formed besides S-phase when nitrided at 450[Formula: see text]C and 480[Formula: see text]C. The specimen treated at 390[Formula: see text]C presents a much enhanced corrosion resistance compared to the untreated substrate. The corrosion resistance deteriorated for samples treated above 450[Formula: see text]C due to the formation of chromium nitrides.

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Lindner, Thomas, Pia Kutschmann, Martin Löbel et Thomas Lampke. « Hardening of HVOF-Sprayed Austenitic Stainless-Steel Coatings by Gas Nitriding ». Coatings 8, n^o 10 (29 septembre 2018) : 348. http://dx.doi.org/10.3390/coatings8100348.

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Austenitic stainless steel exhibits an excellent corrosion behavior. The relatively poor wear resistance can be improved by surface hardening, whereby thermochemical processes offer an economic option. The successful diffusion enrichment of bulk material requires a decomposition of the passive layer. A gas nitriding of high velocity oxygen fuel spraying (HVOF)-sprayed AISI 316L coatings without an additional activation step was studied with a variation of the process temperature depending on the heat-treatment state of the coating. A successful nitrogen enrichment was found in as-sprayed condition, whereas passivation prevents diffusion after solution heat treatment. The phase composition and microstructure formation were examined. The crystal structure and lattice parameters were determined using X-ray diffraction analysis. The identified phases were assigned to the different microstructural elements using the color etchant Beraha II. In as-sprayed condition, the phase formation in the coating is related to the process temperature. The formation of the S-phase with interstitial solvation of nitrogen is achieved by a process temperature of 420 °C. Precipitation occurs during the heat treatment at 520 °C. In both cases, a significant increase in wear resistance was found. The correlation of the thermochemical process parameters and the microstructural properties contributes to a better understanding of the requirements for the process combination of thermal spraying and diffusion.

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Gontijo, L. C., R. Machado, L. C. Casteletti, S. E. Kuri et Pedro A. P. Nascente. « Study of the S Phases Formed on Plasma-Nitrided Austenitic and Ferritic Stainless Steels ». Materials Science Forum 638-642 (janvier 2010) : 775–80. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.775.

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An expanded austenite layer is formed on the surfaces of austenitic stainless steels that are nitrided under low-temperature plasma. This S phase is an iron alloy metastable phase supersaturated with nitrogen. We have identified a similar expanded ferrite or ferritic S phase for nitrided ferritic (BCC) stainless steels. Samples of austenitic AISI 304L and AISI 316L and ferritic AISI 409L stainless steels were plasma-nitrided at 350, 400, 450 and 500°C, and the structural and corrosion characteristics of the modified layers were analyzed by X-ray diffraction (XRD) and electrochemical tests. For the austenitic AISI 304L stainless steel, the results showed that a hard S phase layer was formed on the surface, without corrosion resistance degradation, by using low plasma temperatures (350 and 400°C). A similar behavior was observed for the austenitic AISI 316L stainless steel: the modified layers formed at 350 and 400°C were constituted mainly by the S phase. Plasma-nitriding treatment of the ferritic AISI 409L stainless steel caused the formation of a layer having high amount of nitrogen. XRD measurements indicated high strain states for the modified layers formed on the three stainless steels, being more pronounced for the ferritic S phase.

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Triwiyanto, A., S. Mridha et E. Haruman. « Low Temperature Thermochemical Surface Treatment of Austenitic Stainless Steel for Improved Mechanical and Tribological ». Advanced Materials Research 83-86 (décembre 2009) : 489–96. http://dx.doi.org/10.4028/www.scientific.net/amr.83-86.489.

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This paper describes the results of four thermochemical surface treatments of austenitic stainless steels carried out at 450oC in a fluidised bed furnace and they are nitriding, carburizing and the newly developed hybrid process involving the simultaneous and sequential incorporation of nitrogen and carbon to form a dual layer structure in order to achieve much enhanced surface hardness and wear resistance without compromising the corrosion resistance of the steel. In all these treatments there formed alloyed layers with a common feature of being precipitation-free and supersaturated with nitrogen, or carbon or both in the austenite lattice which is known as S Phase or expanded austenite. However the layer thickness was not uniform in any of these treatments and an effective layer was produced after 8h treatment duration. The nitriding treatment produced thicker and harder layer compared to other treatments; the maximum hardness was over 1500 Hv for nitriding and the minimum hardness of 500 Hv for carburizing treatment. The nitriding treatment sample gave high wear resistance which corresponded to high hardness values.

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Tkacz-Śmiech, Katarzyna, Bartek Wierzba, Bogdan Bożek et M. Danielewski. « Nitrogen Diffusion and Stresses during Expanded Austenite Formation in Nitriding ». Defect and Diffusion Forum 371 (février 2017) : 49–58. http://dx.doi.org/10.4028/www.scientific.net/ddf.371.49.

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Low-temperature nitriding of austenitic stainless steels or chromium containing alloys can produce expanded austenite, known as S-phase, with combined improvement in wear and corrosion resistance. In the paper a critical review of various models for nitrogen diffusion during nitriding is presented. A special attention is paid to the expanded austenite growth. A new model based on bi-velocity method and including stresses is presented. Basic equations and boundary conditions are discussed. Composition dependent nitrogen diffusion coefficient is assumed. Numerical solutions are obtained for the growth of the S-phase layer in steel. The results are compared with previous experiment and calculations.

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Borgioli, Francesca, Emanuele Galvanetto et Tiberio Bacci. « Surface Modification of Austenitic Stainless Steel by Means of Low Pressure Glow-Discharge Treatments with Nitrogen ». Coatings 9, n^o 10 (24 septembre 2019) : 604. http://dx.doi.org/10.3390/coatings9100604.

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When low temperature nitriding of austenitic stainless steels is carried out, it is very important to remove the surface passive layer for obtaining homogeneous incorporation of nitrogen. In the glow-discharge nitriding technique this surface activation is performed by cathodic sputtering pre-treatment, which can heat also the samples up to nitriding temperature. This preliminary study investigates the possibility of producing modified surface layers on austenitic stainless steels by performing low pressure glow-discharge treatments with nitrogen, similar to cathodic sputtering, so that surface activation, heating and nitrogen incorporation can occur in a single step having a short duration (up to about 10 min). Depending on treatment parameters, it is possible to produce different types of modified surface layers. One type, similar to that obtained with low temperature nitriding, consists mainly of S phase and it shows improved surface hardness and corrosion resistance in 5% NaCl solution in comparison with the untreated steel. Another type has large amounts of chromium nitride precipitates, which cause a marked hardness increase but a poor corrosion resistance. These surface treatments influence also water wetting properties, so that the apparent contact angle values become >90°, indicating a hydrophobic behavior.

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de Oliveira, Willian R., Bruna C. E. S. Kurelo, Dair G. Ditzel, Francisco C. Serbena, Carlos E. Foerster et Gelson B. de Souza. « On the S-phase formation and the balanced plasma nitriding of austenitic-ferritic super duplex stainless steel ». Applied Surface Science 434 (mars 2018) : 1161–74. http://dx.doi.org/10.1016/j.apsusc.2017.11.021.

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Li, Xiaoying, Wenbo Dou, Linhai Tian et Hanshan Dong. « Combating the Tribo-Corrosion of LDX2404 Lean Duplex Stainless Steel by Low Temperature Plasma Nitriding ». Lubricants 6, n^o 4 (19 octobre 2018) : 93. http://dx.doi.org/10.3390/lubricants6040093.

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A lean duplex stainless steel, LDX2404, was DC plasma nitrided under a range of treatment conditions. The microstructure characterisation evaluation of the treated samples revealed that a dense, super-hard surface layer can be produced by low-temperature (<450 °C) plasma treatments. The original austenite phase became S-phase and the ferrite phase was supersaturated with nitrogen and ε-Fe3N nitride precipitated from it. When plasma nitriding was carried out at above 450 °C, chromium nitrides precipitated in the surface nitrided layer. Compared to the untreated samples, the surface hardness of the lean duplex stainless steel (DSS) is increased up to four times. The dry wear resistance increased when increasing the treatment temperature. In contrast, the low-temperature treated samples showed the best performance in the electrochemical corrosion and corrosion-wear tests; the performance of the high temperature (>450 °C) plasma nitrided samples was found to be significantly worse than that of the untreated material.

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Fujikawa, Hisao, et Takanori Watanabe. « Structure of Nitrided Layer Formed on Austenitic Stainless Steel by a New Gas Nitriding Process ». Defect and Diffusion Forum 273-276 (février 2008) : 245–49. http://dx.doi.org/10.4028/www.scientific.net/ddf.273-276.245.

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The nitrided layer formed on Type 304 steel after gas nitriding was studied using TEM and so on. (1) Dependency of the nitriding temperature and time on the depth of the nitrided layer was studied. The following equation was obtained. L2=8.7*108*EXP(-146,000/RT)*t (2) Nitrided layer formed at both 570°C for 3 hrs and 410°C for 48 hrs had high density of dislocation, stacking fault and lattice strain. (3) Nitrided layer formed at 570°C was mainly composed of є-Fe3N, and had much Fe4N and CrN. (4) On the other hand, the nitrided layer formed at 410°C was mainly composed of S-phase, є-Fe3N was not detected and Fe4N and CrN were very little. N content in the nitrided layer formed at 410°C was about 7-8 mass%. (5) Nitrided layer formed at 410°C showed good corrosion resistance.

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Borgioli, Francesca. « From Austenitic Stainless Steel to Expanded Austenite-S Phase : Formation, Characteristics and Properties of an Elusive Metastable Phase ». Metals 10, n^o 2 (28 janvier 2020) : 187. http://dx.doi.org/10.3390/met10020187.

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Austenitic stainless steels are employed in many industrial fields, due to their excellent corrosion resistance, easy formability and weldability. However, their low hardness, poor tribological properties and the possibility of localized corrosion in specific environments may limit their use. Conventional thermochemical surface treatments, such as nitriding or carburizing, are able to enhance surface hardness, but at the expense of corrosion resistance, owing to the formation of chromium-containing precipitates. An effective alternative is the so called low temperature treatments, which are performed with nitrogen- and/or carbon-containing media at temperatures, at which chromium mobility is low and the formation of precipitates is hindered. As a consequence, interstitial atoms are retained in solid solution in austenite, and a metastable supersaturated phase forms, named expanded austenite or S phase. Since the first studies, dating 1980s, the S phase has demonstrated to have high hardness and good corrosion resistance, but also other interesting properties and an elusive structure. In this review the main studies on the formation and characteristics of S phase are summarized and the results of the more recent research are also discussed. Together with mechanical, fatigue, tribological and corrosion resistance properties of this phase, electric and magnetic properties, wettability and biocompatibility are overviewed.

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Lee, Insup. « Effect of CH₄ Content on the Characteristics of Surface Layers of Low Temperature Plasma Nitrided 2205 Duplex Stainless Steel ». Materials Science Forum 879 (novembre 2016) : 1074–79. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1074.

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Plasma nitriding was performed on the 2205 duplex stainless steel samples at 400 V with a gas mixture of H2 and N2 for 15 hrs with changing N2 percent, temperature and adding various amounts of CH4. After treatment the behavior of the surface layer was investigated by optical microscopy, X-ray diffraction, GDOES analysis and micro-hardness testing. Potentiodynamic polarization test was also used to evaluate the corrosion resistance of the samples. With increasing both N2 percentage from 10% to 25% and nitriding temperature from 370°C to 430°C, the thickness of nitrogen expanded austenite (S-phase) layer and surface hardness increase up to 16 μm and 1200 HV0.1 at the treatment temperature of 430°C with 25% N2, but decreases the corrosion resistance due to the formation of Cr2N and γ`(Fe, Cr)4N. Thus in order to further increase the thickness of S-phase layer and the corrosion resistance, the influence of adding various amount of CH4 (1% to 5%) in the nitriding atmosphere was investigated. Adding CH4 in the nitriding atmosphere increases the layer thickness compared with that of nitrided sample. The highest thickness can be obtained at 1 % CH4, but addition of CH4 beyond 1 % slightly decreases the layer thickness. Moreover, when nitrided at 400°C with 10% N2 and 5% CH4 content, best corrosion behavior is obtained which also have around 10 μm layer thickness and about 870 HV0.1 surface hardness.

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Li, X. Y. « Joint Second PrizeLow Temperature Plasma Nitriding of 316 Stainless Steel – Nature of S Phase and Its Thermal Stability ». Surface Engineering 17, n^o 2 (avril 2001) : 147–52. http://dx.doi.org/10.1179/026708401101517746.

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Adachi, Shinichiro, et Nobuhiro Ueda. « Formation of S-phase layer on plasma sprayed AISI 316L stainless steel coating by plasma nitriding at low temperature ». Thin Solid Films 523 (novembre 2012) : 11–14. http://dx.doi.org/10.1016/j.tsf.2012.05.062.

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Borgioli, Francesca, Emanuele Galvanetto et Tiberio Bacci. « Effects of Surface Modification by Means of Low-Temperature Plasma Nitriding on Wetting and Corrosion Behavior of Austenitic Stainless Steel ». Coatings 10, n^o 2 (23 janvier 2020) : 98. http://dx.doi.org/10.3390/coatings10020098.

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Low-temperature nitriding of austenitic stainless steels produces modified surface layers, consisting mainly of the S phase, which improve surface hardness and corrosion resistance. Because of the localized plastic deformations, owing to modified layer formation, and ion bombardment occurring during the process itself, this treatment produces also modifications of surface morphology and roughness, which can affect wettability and corrosion behavior. In this study the effects of plasma nitriding, performed using different treatment conditions, on the surface morphology and roughness, and thus on wettability and corrosion resistance, of AISI 202 specimens with different initial finishings (2D and polished finishing) were investigated. Different probe liquids, having both high (bi-distilled water and solution of 3.5% NaCl) and low (ethanol and rapeseed oil) surface tension, were employed for assessing the wetting behavior with the sessile drop method. The contact angle values for water increased markedly when nitriding was performed on polished samples, while this increase was smaller for 2D samples, and on selected specimens a hydrophobic behavior was observed. Very low contact angle values were registered using low surface tension liquids, suggesting an oleophilic behavior. Corrosion resistance in a 5% NaCl solution was assessed, and it depended on the characteristics of the nitrided specimens.

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Kim, Sang-Gweon, Kook-Hyun Yeo, Yong-Ki Cho, Jae-Hoon Lee et Masahiro Okumiya. « The Phenomenon of High Hardness Values on the S-Phase Layer of Austenitic Stainless Steel via Screen Plasma Nitriding Process ». Advances in Materials Physics and Chemistry 08, n^o 06 (2018) : 257–68. http://dx.doi.org/10.4236/ampc.2018.86017.

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KAHRAMAN, FATIH, GÖKÇE MEHMET GENÇER, AYÇA D. KAHRAMAN, COŞKUN YOLCU et HAYDAR KAHRAMAN. « LOW-TEMPERATURE NITRIDING BEHAVIOR OF COMPRESSIVE DEFORMED AISI 316Ti AUSTENITIC STAINLESS STEELS ». Surface Review and Letters 26, n^o 05 (juin 2019) : 1850188. http://dx.doi.org/10.1142/s0218625x18501883.

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The effects of compressive cold deformation under the quasi-static loads on the nitride formation, nitride layer growth and surface hardness properties were researched in this study. Martensite structure did not form in AISI 316Ti stainless steel as a result of quasi-static deformation. Diffusion layer did not form in all nitrided samples. Both the deformed and undeformed samples have only compound layer on the surfaces at the low-temperature nitriding conditions (400∘C, 7[Formula: see text]h). According to the X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS) and electron probe microanalysis (EPMA) results, S-phase and chromium nitride (CrN) were formed in the compound layers of the deformed samples. However, CrN did not form in the compound layer of the undeformed sample. The optical microscope (OM) results showed that the compressive cold deformation increased the nitrogen diffusion rate and led to thicker nitrided layer than the undeformed sample under the same plasma-nitriding conditions. All nitrided layers presented higher microhardness values ([Formula: see text][Formula: see text]HV) when compared with the untreated sample hardness. It was also verified that the deformation amount did not affect significantly the nitrided layer hardness.

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Kartika, Ika, Kevin Kurnia, Galih Senopati, Joko Triwardono, Bambang Hermanto, Fendy Rokhmanto, Made Subekti Dwijaya et Alfirano Alfirano. « The effect of cold rolling and high-temperature gas nitriding on austenite phase formation in AISI 430 SS ». Eastern-European Journal of Enterprise Technologies 4, n^o 12(112) (26 août 2021) : 25–32. http://dx.doi.org/10.15587/1729-4061.2021.234174.

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Austenitic stainless steel is the most commonly used material in the production of orthopedic prostheses. In this study, AISI 430 SS (0.12 wt. % C; 1 wt. % Si; 1 wt. % Mn; 18 wt. % Cr; 0.04 wt. % P and 0.03 wt. % S) will be modified by creating austenite and removing its ferromagnetic properties via the high-temperature gas nitriding process. Cold rolling with various percentage reduction (30, 50, and 70 %) was followed by gas nitriding at a temperature of 1200 °C with holding times of 5, 7, and 9 hours, then quenching in water was carried out on as-annealed AISI 430 SS. The formation of the austenite phase was examined by XRD (x-ray diffraction). The microstructure and element dispersion were observed using SEM-EDS (scanning electron microscope-energy dispersive spectrometry), whereas the mechanical properties after gas nitriding and water quenching were determined by Vickers microhardness testing. At all stages of the gas nitriding process, the FCC iron indicated the austenite phase was visible on the alloy's surface, although the ferrite phase is still present. The intensity of austenite formation is produced by cold rolling 70 % reduction with a 5-hour gas nitriding time. Furthermore, the nitrogen layer was formed with a maximum thickness layer of approximately 3.14 µm after a 50 % reduction in cold rolling and 9 hours of gas nitriding process followed by water quenching. The hardness reached 600 HVN in this condition. This is due to the distribution of carbon that is concentrated on the surface. As the percent reduction in the cold rolling process increases, the strength of AISI 430 SS after gas nitriding can increase, causing an increase in the number of dislocations. The highest tensile strength and hardness of AISI 430 SS of 669 MPa and 271.83 HVN were obtained with a reduction of 70 %.

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MIKI, Yasuhiro, Akio NISHIMOTO et Takazumi TAMIYA. « X-Ray Residual Stress in the S-Phase of Stainless Steel Nitrided by Plasma Nitriding Method and Residual Stress Measurement of DLC Film Deposited on the S-Phase ». Journal of the Society of Materials Science, Japan 65, n^o 7 (2016) : 517–24. http://dx.doi.org/10.2472/jsms.65.517.

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MIKI, Yasuhiro, Akio NISHIMOTO et Takazumi TAMIYA. « X-Ray Residual Stress in the S-Phase of Stainless Steel Nitrided by a Plasma Nitriding Method and Residual Stress Measurement of a DLC Film Deposited on the S-Phase ». Journal of the Society of Materials Science, Japan 67, n^o 7 (15 juillet 2018) : 715–21. http://dx.doi.org/10.2472/jsms.67.715.

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« Dry Sliding Wear Behavior of AISI310 Stainless Steel with Low Temperature Salt Bath Nitriding and Gas Nitriding Processes ». International Journal of Engineering and Advanced Technology 9, n^o 1 (30 octobre 2019) : 470–73. http://dx.doi.org/10.35940/ijeat.a9570.109119.

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AISI 310 is an austenitic stainless steel that accomplished in high thermal applications like turbines, boiler parts etc. In this study AISI310 was treated with salt bath nit- -riding for 60min, 120min and 150min and gas nitriding for 6hrs, 12hrs and 18hrs at the temperature of 5700 c respectively. Comparison study of nitrided specimens were performed under various metallographic tests like scanning electron microscope, X-ray Diffraction, pin on disc apparatus. Experimental results shown that when salt bath nitrided sample at 150min showed a white layer called “S-phase” layer which was detected. In gas nitriding also “S-phase” layer, an expanded austenite was observed, after 18 hrs, CrN phase was discovered after the decomposition of s-phase layer gas nitrided sample of 18hrs which showed the best corrosion resistance .Salt bath specimen 150 min showed minimum wear loss and gas nitrided sample of 18hrs showed more hardness, minimum wear and improved corrosion resistance compared to untreated sample.

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Li, G. Y., Z. Y. Wang et M. K. Lei. « Transition of Wear Mechanisms of Plasma Source Nitrided AISI 316 Austenitic Stainless Steel Against Ceramic Counterface ». Journal of Tribology 134, n^o 1 (1 janvier 2012). http://dx.doi.org/10.1115/1.4005516.

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A single high-nitrogen face-centered-cubic (f.c.c.) phase (γN) layer formed on the plasma source nitrided AISI 316 austenitic stainless steel at a nitriding temperature of 450 °C for a nitriding time of 6 h. An approximately 17 μm-thick γN layer has a peak nitrogen concentration of about 20 at. %. Tribological properties of the γN phase layer on a ball-on-disk tribometer against an Si3N4 ceramic counterface under a normal load of 2 and 6 N with a sliding speed of 0.15 to 0.29 m/s were investigated by friction coefficient and specific wear rate measurement. Worn surface morphology and wear debris were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The microhardness of the γN phase layer on the nitrided stainless steel was measured as about 15.1 GPa. The change in the friction coefficient of the γN phase layer on the stainless steel was dependent on the applied normal load, which was associated with that in the specific wear rate. Under a lower normal load of 2 N, the lower specific wear rate of the γN phase layer with a sliding speed of 0.15 m/s was obtained as 2.8 × 10−6 mm3/N m with a friction coefficient of 0.60. Under a higher normal load of 6 N, the lower specific wear rate with a sliding speed of 0.29 m/s was 7.9 × 10−6 mm3/N m with a friction coefficient of 0.80. When the applied load increased from 2 to 6 N, a transition of the wear mechanisms from oxidative to abrasive wear was found, which was derived from the oxidation reaction and the h.c.p. martensite phase transformation of the γN phase during the wear tests, respectively.

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