Stress induced and concentration dependent diffusion of nitrogen in plasma nitrided austenitic stainless steel

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• 作者：Teresa Moskalioviene^a ; ^{galdikas@ktu.lt} ; Arvaidas Galdikas^a ; ^b
• 关键词：Austenitic stainless steel ; Plasma nitriding ; Internal stress ; Nitrogen diffusion ; Concentration dependent diffusion coefficient ; Modelling
• 刊名：Vacuum
• 出版年：2012
• 期刊代码：83_0042207x
• 类别：ph
• 出版时间：27 April, 2012
• 卷：86
• 期：10
• 页码：1552-1557
• 文件大小：685 K

摘要

The nitrogen transport mechanism in austenitic stainless steel during plasma nitriding at moderate temperatures (around 400聽掳C) is considered by stress induced diffusion model. The model involves diffusion of nitrogen in presence of internal stresses gradient induced by penetrating nitrogen as the next driving force of diffusion after concentration gradient. Furthermore, in the present work it was found that nitrogen diffusion coefficient vary with nitrogen concentration according to well-known Einstein-Smoluchowski relation D(C_N)聽=聽f(1/C_N). Nitrogen depth profiles in nitided AISI 316L steel at T聽=聽400聽掳C for 1, 3 and 8聽h calculated on the basis of this model are in good agreement with experimental nitrogen profiles. The dependencies of nitrogen flux and nitriding time on nitrogen concentration, nitrogen surface concentration and penetration depth are analyzed by proposed model. It is shown that, with the increase of nitriding time the compositionally-induced stresses and thickness of stressed steel layer increases.