Study on the mechanism of intergranular stress corrosion cracking and analysis of residual stress and work hardening in welds of low-carbon austenitic stainless steel with hard surface machining

Mori, Hiroaki*; Katsuyama, Jinya  ; Mochizuki, Masahito*; Nishimoto, Kazutoshi*; Toyoda, Masao*

In order to clarify the effects of residual stress and hardening on intergranular stress corrosion cracking (IGSCC) behavior in the welds of Type 316L stainless steel with surface hardening, the residual stress and hardness in the butt joint of pipes were estimated and grain boundary sliding was analyzed from the viewpoint of microdeformation. The residual stress and hardness in hard-machined surfaces near welds was clarified from experiment and analysis method. Grain boundary sliding in the cold-rolled specimen occurs in smaller strain conditions than that in as-received specimen; the amount of grain boundary sliding increases remarkably with an increase in rolling reduction. We also clarified that grain boundary energy is raised by grain boundary sliding. On the basis of the results, we concluded that the cause of IGSCC in the welds of Type 316L stainless steel with surface hardening is the increase in grain boundary energy induced by residual stress of welding and surface hardening.