Effect of additive alloying element on plasma nitriding and carburizing behavior for austenitic stainless steels

Egawa, Motoo; Ueda, Nobuhiro; Nakata, Kazuhiro; Tsujikawa, Masato; Tanaka, Manabu

doi:10.1016/j.surfcoat.2010.07.093

Cited by 45 publications

(37 citation statements)

References 6 publications

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“…The characteristics of the nitrided layers depend on different nitriding techniques [1,[7][8][9][10], treatment parameters [1,3,[11][12][13][14] and alloy composition [1,3,11,15,16]. Even if the main critical parameter, which influences microstructure and phase composition of the modified layers, is recognized to be the treatment temperature, also treatment pressure plays a very important role.…”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Austenitic Stainless Steel by Means of Low Pressure Glow-Discharge Treatments with Nitrogen

2019

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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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Section: Introductionmentioning

confidence: 99%

Surface Modification of Austenitic Stainless Steel by Means of Low Pressure Glow-Discharge Treatments with Nitrogen

2019

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“…It is formed at the surface when nitrided at a low temperature such as 673 K for γ stainless steel. Since then, S phase formed by gas carburizing/nitriding or plasma carburizing/nitriding has been studied widely [4][5][6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

“…CH 4 + e − → CH * + H 2 + H + e − (5) Conceivably, CH 4 gas excited by plasma generated on the screen and the specimen surface becomes the hydrocarbon radical cation (CH*) and carbocation (C + ), respectively, as shown in reactions (6) to (8), and they can diffuse from the surface to the inside of a steel specimen.…”

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confidence: 99%

Effects of Heat Treatment Conditions on Formation of Expanded-Austenite Phase in Austenitic Stainless Steels by Combining Active Screen and DC Plasma Carburizing Processes

Satomi

Kanayama²,

Watanabe

et al. 2017

Mater. Trans.

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A low temperature plasma carburizing process can produce an expanded-austenite layer (generally called the S phase), which has high hardness and corrosion resistance at the surface of austenitic stainless steels. We have investigated S phase formation behaviors by using a combined process of active screen and DC plasma carburizing for austenitic stainless steels such as JIS SUS304 and 316 with the aim of developing a highly effective and ef cient production technique. The in uence of carburizing parameters (processing temperature, time, gas atmosphere, etc.) on the formation of the S phase was studied in terms of thickness, hardness, carbon concentration, lattice constant, and residual stress. The mechanical properties and corrosion resistances of the obtained S phases were also evaluated by using a ball-on-disk test and a salt spray test (SST). The results show that S phases produced ef ciently by the combined process under a condition of 733 K and a 10.5 vol% of CH 4 gas ratio have both excellent wear and corrosion resistances.

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“…Plasma nitriding is becoming increasingly popular due to its high nitrogen potential, short treatment time and low environmental impact. [1][2][3][4][5][6][7] However, the components to be treated are subjected to a high cathodic potential in traditional DC plasma nitriding (DCPN), which results in the production of plasma directly on their surface. As a result, edge effect, arcing and hollow cathode occur.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Deposits on Nitriding Layer Formation of Active Screen Plasma Nitriding

2016

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Austenitic stainless steel SUS 316L was nitrided by active-screen plasma nitriding (ASPN) to investigate the effect of surface deposits from the screen on the nitriding layer formation. ASPN experiments were carried out using a DC plasma-nitriding unit. The sample was placed on the sample stage in a oating potential (bias-off) and a cathodic potential (bias-on). The screen, which was SUS 316L expanded metal with 38% open area ratio, was mounted on the cathodic stage around the sample stage. Nitriding was performed in a nitrogen-hydrogen atmosphere with 25% N 2 + 75% H 2 for 18-180 ks at 673 K under 200 Pa by the ASPN process. After nitriding, the nitrided samples were examined using scanning electron microscopy, X-ray diffraction, Vickers microhardness and glow discharge optical emission spectroscopy. From the surface observation of the nitrided sample, deposits were observed on the top surface of the sample nitrided with bias-off whereas deposits were not on that nitrided with bias-on. The nitrogen-expanded austenite (S phase) was formed on the surface of both samples. Layer thickness of the S phase increased with increasing the nitriding time. Additionally, the degree of an increase of the layer thickness of the S phase nitrided with bias-on was approximately 2.5 times greater than that nitrided with bias-off. This result suggests that the ASPN treatment with bias-on is effective for the increase of the nitriding layer thickness.

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Effect of additive alloying element on plasma nitriding and carburizing behavior for austenitic stainless steels

Cited by 45 publications

References 6 publications

Surface Modification of Austenitic Stainless Steel by Means of Low Pressure Glow-Discharge Treatments with Nitrogen

Surface Modification of Austenitic Stainless Steel by Means of Low Pressure Glow-Discharge Treatments with Nitrogen

Effects of Heat Treatment Conditions on Formation of Expanded-Austenite Phase in Austenitic Stainless Steels by Combining Active Screen and DC Plasma Carburizing Processes

Effect of Surface Deposits on Nitriding Layer Formation of Active Screen Plasma Nitriding

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