Influence of tensile pre-strain and sensitization on martensite reversion mechanism in austenitic stainless steel

The martensitic phase transformation and reverse transformation of AISI 304 austenitic stainless steel by tensile pre-strain and sensitization at 948 K were investigated by X-ray diffraction. Martensite reversion was found to occur by an athermal shear mechanism at this temperature. A small quantity of “supposed secondary α′-martensite” was generated in a specimen suffering 40% engineering strain after being sensitized for a long time and water quenched. This could be due to the redistribution of carbon and chromium in the reverted austenitic phase and dislocations, which promoted the nucleation of the martensitic transformation.

► Reversed transformation of strained stainless steel was shear.
► Sensitization induced “supposed secondary α′-martensite”.
► “Supposed secondary α′-martensite” was facilitated by sheared austenite.