Investigation on nucleation of intergranular stress corrosion cracking in austenitic stainless steel by in situ strain measurement

摘要

This study evaluates the nucleation criterion for intergranular stress corrosion cracking (SCC) on a smooth surface of type 304 austenitic stainless steel from a mechanical viewpoint. SCC testing was conducted under a constant load, and microscopic strains on a smooth surface were measured in situ by the digital image correlation technique. The initiation period and site of intergranular cracks were estimated from the change in the microscopic strain distribution near grain boundaries (GBs), and the crack initiation was evaluated using strains at GBs just before cracking. As a result, the initiation of an intergranular crack could be characterized by evaluating only the maximum normal strain along the GB. The criterion for crack initiation was determined to be a maximum normal strain >0.01 from the viewpoint of local strain.