A low-temperature study to examine the role of ε-martensite during strain-induced transformations in metastable austenitic stainless steels

A low-temperature study of the mechanical behaviour of a metastable semi-austenitic stainless steel was carried out. This class of stainless steels is found to show a characteristic hump followed by softening in their stress-strain curves, especially at low temperatures, much like dynamically recrystallizing steels. Experiments are carried out at sub-zero temperatures to examine this phenomenon. Samples are subjected to various metallographic, X-ray and transmission electron microscopy techniques to identify the evolution of the different phases. The presence of an intermediate phase ε-martensite is detected which might cause a softening in the stress-strain behaviour, comparable with the formation in other low stacking fault energy stainless steels.