Affect on stress corrosion cracking due to surface hardened layer at welding parts of stainless steel pipings

The effects of the hardened surface layer at the welding parts of stainless steel piping on the occurrence of stress corrosion cracking (SCC) were confirmed through experiments. Assuming that SCC occurs and develops due to the localized oxidation of the material surface, an oxidation test was performed under constant stress in high-temperature water using notched round bar specimens suitable for stress loading. The pieces of 316L stainless steel and 15Ni-15Cr stainless steel were used as test materials. From observation of the test specimens, it was clarified that there is a difference in the formation shape of the surface oxide film due to the stress and surface hardened layer, and also there is the influence of the stress on the peeling form of the oxide film outer layer of the surface. It is important to apply mirror finishing after the turning machining of the welding part. (A.O)