Chloride-induced stress corrosion crack propagation mechanisms in austenitic stainless steel are mechanically driven

Abstract

The objective of this study is to understand the mechanical aspects of chloride-induced stress corrosion cracking (CISCC) in austenitic stainless steel. CISCC is a critical degradation mode in austenitic stainless steel, so understanding its mechanisms is essential for predicting material integrity and lifetime. Here, CISCC is studied by transmission Kikuchi diffraction and transmission electron microscopy for two cases: propagation into a lower Schmid factor grain and a higher Schmid factor grain. The evolution of deformation fields near the crack-tip is estimated through local misorientations and geometrically necessary dislocations, and are more severe in the lower Schmid factor grain. In both grain types, cross slips are distributed closer to the crack, while co-planar slips appear away from the crack, revealing consistent crack-tip deformations. Strain-induced α’-martensite transformations occur in the higher Schmid factor grain. These results imply that grain texture can be used to predict and mitigate CISCC propagation in austenitic stainless steel.