Interplay of irradiation stress and phase stabilizer in determining the direction of martensitic transformation in SS316

Abstract

It is expected that radiation damage in austenitic stainless steels caused by Au and Ag ions will result in a forward martensitic transformation (MT), which should be proportional to the induced radiation stresses and hence the fluence. However, contrary to this intuitive understanding, we find that up to a critical fluence, instead of showing a forward MT, cold-worked SS316 shows restoration of austenite through reverse MT. Our x-ray diffraction (XRD) and magnetization measurements confirm these results. It is observed that despite a lower DPA in Au-damaged steel as compared to Ag, forward MT is observed only in the former case. With the help of ab-initio calculations, we have explained why reverse MT due to Au ions is more than the Ag ions till a critical fluence. Our studies show a strong interplay of irradiation stress and phase stabilizer in determining the direction of MT in SS316.