Influence of the Chemical Composition on the Behavior of Austenitic Stainless Steel in Fluid Layer Nitriding Process
Abstract
The main factors that influence the stainless steel behavior to the nitriding process are: chemical composition, nitriding temperature, treatment time. Researches have revealed that, with low temperature nitriding, the chemical composition expressed directly by the alloying elements or indirectly by the austenite or ratio ECr/ENi stability index decisively influences the characteristics of the nitride layer. The high alloyed steels having over 50% alloying element and high stability index S = 30, produce a diffusion layer of a low nitrogen concentration, below the saturation limit, and hardness less than 500 HV005. The usual stainless steels CrNi, CrNiMo of low stability index S = 17.5-24 at 500 oC, within the sensitive temperature range form high hardness combinations (1200-1400 HV005) and at temperatures of 450 oC under the sensitive range, diffusion layers of high nitrogen concentrations close to the saturation limit, featuring high hardness 1100-1200 HV005 and slightly lower depths, tens of microns.
Downloads
References
[2]. Bard A.J., Faulkner L.R., 2000, “Electrochemical methods, Fundamentals and aplications” Wiley Science Publication.
[3]. Dima O. Cazacu N., 2006, “Surface hardening by nitration for some stainless austenite steel types.” Simpozionul international “Turnatoria de la rigoarea tehnica la arta” Ed. ACADEMICA Galati.
[4]. Dima O. Levcovici S. Georghies C., 2006, “Aspects of nitrated layer structure for some types of austenite stainless steel" Simpozionul international “Turnatoria de la rigoarea tehnica la arta” Ed. ACADEMICA Galati.
[5]. Dima O. Mitoseriu O., 2006, “Behavior of some stainless nitrated austenite steel types to corrosion and abrasion”. Simpozionul internation “Turnatoria de la rigoarea tehnica la arta” Ed. ACADEMICA Galati.
[6]. Fossati A, Borgioli F, Galvanetto E, Bacci T. 2006, “Corrosion resistance properties of glow-discharge nitrided AISI316L austenitic stainless steel in NaCl solution” Corrosion Science, Vol.48, Issues 6, June 2006, p. 1513-1527.
[7]. Gheorghies C. s.a., 1994, “Incercarea materialelor Vol.III” Ed. Tehnica Buc.
[8]. Levcovici S.M. s.a., 2003, “Ingineria suprafeţelor“ EDP, RA Buccureşti.
[9]. Mirkin L.I., 1979, “Controlul cu raze X a structurii materialelor” Moscova.
[10]. ***, STAS 9229 -1995 “Incercarea rezistenţei la coroziune in ceata salina”.
[11]. ***, STAS 9639-1981 “Incercarea la uzura prin abraziune”.
