On the Nature, Properties and Wear Response of S-phase (nitrogen-alloyed Stainless Steel) Coatings on Aisi 316l

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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Corrosion-wear response of sputtered CrN and S-phase coated austenitic stainless steel

Surface and Coatings Technology ◽

10.1016/s0257-8972(99)00222-4 ◽

1999 ◽

Vol 116-119 ◽

pp. 1161-1165 ◽

Cited By ~ 21

Author(s):

G. Aldrich-Smith ◽

D.G. Teer ◽

P.A. Dearnley

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steel ◽

S Phase ◽

Corrosion Wear ◽

Wear Response

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Study of the S phase formed on plasma-nitrided AISI 316L stainless steel

Materials Science and Engineering A ◽

10.1016/j.msea.2006.06.023 ◽

2006 ◽

Vol 431 (1-2) ◽

pp. 315-321 ◽

Cited By ~ 51

Author(s):

L.C. Gontijo ◽

R. Machado ◽

E.J. Miola ◽

L.C. Casteletti ◽

N.G. Alcântara ◽

...

Keyword(s):

Stainless Steel ◽

316L Stainless Steel ◽

S Phase ◽

Aisi 316L ◽

Aisi 316L Stainless Steel

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Wear and Corrosion Behavior of Cold Gas Sprayed Stainless-Steel Coatings Using Solution-Hardened AISI 316L Powder

Thermal Spray 2021: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc2021p0209 ◽

2021 ◽

Author(s):

Thomas Lindner ◽

Pia Kutschmann ◽

Maximilian Grimm ◽

Martin Löbel ◽

Jochen Fiebig

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steels ◽

Scratch Resistance ◽

Aisi 316L ◽

Austenitic Phase ◽

Surface Protection ◽

Wear And Corrosion ◽

Application Potential ◽

Stainless Steel Coatings ◽

Cold Gas

Abstract Due to their excellent corrosion resistance; austenitic stainless steels are suitable for surface protection applications. However; the application potential is often limited by the low wear resistance. An interstitial hardening of the surface layer area can solve this problem for massive wrought alloys. Further potential for improvement lies in the transition to surface technology. For this purpose; powder feedstock of the stainless-steel grade AISI 316L was gas nitrocarburized at low temperatures. The formation of a metastable expanded austenitic phase was achieved. Subsequently; the processing was carried out by cold gas spraying. Due to the simultaneously high process kinetics and low thermal load; dense coatings were produced while maintaining the metastable state of the feedstock. When compared to solid reference systems; the scratch resistance saw a marked improvement.

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MICROSTRUCTURE, MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF AISI 316L STAINLESS STEEL DURING SALT BATH NITRIDING

Acta Metallurgica Slovaca ◽

10.36547/ams.27.2.952 ◽

2021 ◽

Vol 27 (2) ◽

pp. 47-52

Author(s):

Elhadj GHELLOUDJ

Keyword(s):

Stainless Steel ◽

Surface Hardness ◽

Salt Bath ◽

S Phase ◽

Current Work ◽

Tribological Characteristics ◽

Aisi 316L ◽

Surface Microstructures ◽

The Impact ◽

Salt Bath Nitriding

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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