Enhanced corrosion resistance of Cr-Mn ASS by low temperature salt bath nitriding technique for the replacement of convectional Cr-Ni ASS

Abstract

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.

Citation

Tandon, V., Patil, A.P. and Rathod, R.C. (2019), "Enhanced corrosion resistance of Cr-Mn ASS by low temperature salt bath nitriding technique for the replacement of convectional Cr-Ni ASS", Anti-Corrosion Methods and Materials, Vol. 66 No. 4, pp. 439-445. https://doi.org/10.1108/ACMM-10-2018-2013