Magnetic properties on thermally sensitized austenitic stainless steels with different chemical composition were investigated. Ferromagnetic martensite phase appeared along grain boundary (GB) by thermal sensitization. As value of Ni equivalent increased and carbon content decreased, the ferromagnetic martensite decreased. The former phenomenon is related to structural stability of austenitic phase, while the latter to shortage of carbon for carbide formation. These behaviors can be explained consistently by considering the change of martensitic transition temperature due to Cr depletion at the GB.
