Effects of Applied Strain and Sensitization on SCC Behavior of 304 Stainless Steel in Atmospheric Corrosion Environments

Abstract

Austenitic stainless steels have relatively good corrosion resistance due to the formation of a Cr-rich passive film. However, in atmospheric corrosion environments near seashore, austenitic stainless steels can suffer from localized attacks such as pitting corrosion and crevice corrosion. This is due to the formation of thin water layers containing high concentration of chloride ions on the stainless steels. In addition, when the steels are subjected to tensile stress or deformation, stress corrosion cracking (SCC) can occur from pits. Since it is well-know that sensitization can enhance SCC susceptibility of austenitic stainless steels, it is needed to clarify the effect of deformation and sensitization on the SCC of the steels in atmospheric corrosion environments. In this study, crack initiation and propagation behavior of sensitized 304 stainless steels was investigated under a MgCl2 solution droplet. The experimental results demonstrated that cracks were initiated from pits by applying plastic deformation. It was confirmed that hydrogen evolution was observed during propagation of the cracks. In the presentation, SCC mechanism of sensitized 304 stainless steels in atmospheric corrosion environments will be discussed.