Role of surface mechanical attrition treatment and chemical etching on plasma nitriding behavior of AISI 304L steel

In the present study, the effect of surface mechanical attrition treatment (SMAT) on corrosion resistance and plasma nitriding behavior of AISI 304L stainless steel (SS) was investigated. Mechanical twins and deformation induced martensite phase were observed in the SMAT affected region. SMAT improved the corrosion resistance and nitriding kinetics of AISI 304L SS. Effective nitriding time and hence, the thickness of the nitrided layer were increased with increase in the duration of chemical etching and a decrease in the stability of passive layer on the SMATed specimens. Surface hardness of the nitrided specimens was dependent on the formation of expanded austenite (γN) and its decomposition (especially, at higher effective nitriding time).