Study on the mechanical stability of reversed austenite in super martensitic stainless steel via in-situ synchrotron high energy X-ray diffraction

Abstract

This study investigated the mechanical stability of two types of reversed austenite, film-like and blocky reversed austenite, which were obtained after tempering for different time at 620 °C in 16%Cr-5%Ni super martensitic stainless steel. Herein, synchrotron high-energy X-ray diffraction combined with in-situ tensile testing was performed. The results indicate that most of the blocky reversed austenite transformed into martensite early at the elastic stage, while the stress induced martensitic transformation of film-like reversed austenite mainly occurred after yield. The increase in chemical driving force caused by the lower degree of Ni enrichment, the decrease in strain energy due to matrix softening, and the lower interfacial energy due to the smaller specific surface area were considered possible reasons for the poor mechanical stability of blocky reversed austenite.