A new type of low temperature sensitization of austenitic stainless steels enhanced with defect-solute interactions

Analyses of changes in corrosion characteristics, microstructure and mechanical properties during aging of cold-worked type 304 and 316 steels have indicated that there is a temperature zone between 400 and 500deg C where an aging-induced ductility minimum exists. The metallurgical change associated with the phenomenon is suggested to enhance the trend of environmentally-assisted cracking under typical fusion reactor conditions, particularly under coexistence of neutrons. Unlike the sensitization due to carbide precipitation at higher temperatures, a new mechanism is proposed which is related to austenite stability and particularly to strain-induced martensite formation in which solute-defect interactions play an important role. (orig.)