Development of shape memory effect in an Fe-based alloy under heavy cold rolling

This research was conducted to examine the effect of heavy cold rolling process on the microstructureand shape memory effect (SME) of Fe-۹.۵Ni-۶.۵ Mn (wt.%) steel. Experimental results such as X-raydiffraction (XRD) and electron backscatter diffraction (EBSD) analyses revealed that themicrostructure of the initial alloy in the solution annealed condition was a fully lath -martensitewith a high density of dislocation. Under heavy cold rolling with ۹۰% reduction in thickness, theaustenite () phase with a fine grain size was partially induced in the martensite matrix through ashear  transformation, resulting in the development of a dual-phase () steel. Strain-inducedaustenite inherited the dislocation structure from the parent martensite due to the shear nature of thetransformation. The tensile test results indicated a shape recovery of ۳۵% at ۱% pre-strain for thecold rolled specimen. The presence of austenite phase with high density of dislocation in the dualphasesteel was the main reason for appearance the SME.

Keywords:

Fe-Ni-Mn steel , Cold rolling , Microstructure , Austenite , Shape memory effect