Mechanistic contribution of the interplay between microstructure and plastic deformation in hot-rolled Fe-11Mn-2/4Al-0.2C steel

We elucidate here the mechanistic contribution of the interplay between microstructural constituents and plastic deformation behavior in hot-rolled Fe-0.2C-11Mn-2Al (2Al steel) and Fe-0.2C-11Mn-4Al (4Al steel) transformation induced plasticity (TRIP) steels. The steel containing lower aluminum content (2 wt%) was characterized by excellent combination of tensile elongation (TE) of 31.4%, ultimate tensile strength (UTS) of 1407 MPa, and UTS×TE of 44.2 GPa%, where the ultrahigh strength is attributed to the cumulative contribution of the newly transformed martensite with high microhardness and Portevin-Le Chatelier (PLC) effect. In contrast, the higher aluminum (4 wt%) containing steel indicated lower UTS of <1200 MPa, but higher TE of 34-40%, which resulted from the TRIP effect and the cooperative deformation of α-ferrite and δ-ferrite.