Corrosion conduct of Austenitic stainless steel 316L subjected to surface treatment

Abstract

The influence of low temperature liquid nitriding as a surface heat treatment analogy with laser peening treatment at the various of throbs on pitting corrosion of the “AISI 316L Austenitic stainless steel” is investigated in this paper. According to typical ASTM (G71-31) a number of corrosion examination samples are equipped with the measurements of (15 * 15 * 3) mm which distributed into the many groups. Three sets were exposed to liquid nit riding process at temperatures of (500, 400, 300) Co for one hour. The specimens (without coating) were exposed to a number of the throbs (1,2,3) by laser peening. Microstructure variations, compression residual stress, hardness, were inspected in this work. The corrosion and its variables (potential cell, current density) were also evaluated using the potential stat examination and applying the Tafel method using saltwater solution (3.5% NaCl). Tafle equation was used to compute the corrosion degree. The results revealed that the liquid nitriding participated to raise the corrosion rate at (500) Co, compared to the original metal because of chromium nitride and also leaser peening participated to the increase in the corrosion rate due to plastic deformation which led to the heterogeneity in the microstructure but liquid nitriding at temperature (400) °C gave the best result where it was closer to the parent metal’s, also laser peening at one throb showed the lower corrosion rate.