In the present investigation, an attempt has been made to investigate the replacement compatibility of conventional austenitic stainless steel (316L) with low-Ni austenitic stainless steel (201) by employing their dissimilar welding using gas tungsten arc welding technique with varying heat input. The effects of heat input on the microstructural, mechanical, and corrosion properties were studied. The result depicts the balanced austenite/ferrite content in the fusion zone for both the heat inputs. The low heat input process, which results in a faster cooling rate, demonstrates higher tensile strength and microhardness. Similarly, the pitting corrosion resistance of the fusion zone demonstrates better properties on the low heat input process attributed to the lesser dendritic length and lesser interdendritic arm spacing.

Purpose The purpose of this paper is to enhance the corrosion resistance of Cr-Mn austenitic stainless steel (ASS) via low temperature salt bath nitriding and to replace the convectional Cr-Ni ASS with newly developed enhanced corrosion resistive Cr-Mn ASS. Design/methodology/approach The low temperature salt bath nitriding was performed on Cr-Mn ASS at 450°C for 3 h in potassium nitrate salt bath. Findings The present paper compares the corrosion resistance of salt bath nitrided Cr-Mn ASS with convectional Cr-Ni ASSs (316 L and 304 L ASSs) in 3.5 per cent NaCl by electrochemical techniques. The electrochemical impedance spectroscopy result shows the increase in film resistance and potentiodynamic polarization results show the enhanced corrosion resistance of nitrided Cr-Mn ASS, which is almost equivalent to that of 316 L and 304 L ASSs. This is attributed to the formation of nitrogen supersaturated dense nitride layer. The present results therefore suggest that the nitrided Cr-Mn ASS may replace costly convectional Cr-Ni ASSs for commercial and industrial applications. Originality/value Ever-increasing price of nickel (Ni) is driving the industries to use Ni-free or low-Ni austenitic stainless steels (ASSs). But its corrosion resistance is relatively poor as compared to conventional Cr-Ni ASSs. However, its corrosion resistance can be improved by nitriding. The low temperature salt bath nitriding of Cr-Mn ASS and its electrochemical behavior in 3.5 per cent NaCl has not been studied. The present research paper is beneficial for industries to use low cost Cr-Mn, enhance its corrosion resistance and replace the use of costly conventional Cr-Ni ASSs.

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