Effect of aluminium on deformation mode and mechanical properties of austenitic FeMnCrAlC alloys

This work is concerned with the effects of Al on the deformation mode and tensile properties of Fe19Mn5Cr(0–5.5)Al0.25C alloys. The deformation mode at room temperature shifted from (ε + α′) martensites to deformation twinning to slip with increasing Al content. Al increased the stacking fault energy at a rate of 10 mJ mm−2 wt.%−1, which is sufficiently high to give birth to the large variation of the deformation mode. On the other hand, bct α′ martensites were induced during deformation at low temperatures, together with deformation twins. The formation of bct α′ martensites was preceded by the prior formation of deformation twins. Fe19Mn5Cr3.5Al0.25C alloy composition exhibited excellent elongations exceeding 65% at both room temperature and 77 K. It was found in this work that the sequential formation of strain-induced deformation twins and α′ martensites was responsible for exhibiting excellent elongations at both room temperature and 77 K.