Microstructure and deformation behavior of the hot-rolled medium manganese steels with varying aluminum-content

We elucidate here the mechanistic contribution of the interplay between microstructural constituents and plastic deformation behavior in hot-rolled Fe-0.2C-11Mn-xAl steels containing 2-6 wt% Al. The decrease in austenite fraction with increase in Al-content was accompanied by decrease in tensile strength, while the δ-ferrite content and ductility increased. 2Al steel was characterized by ultrahigh ultimate tensile strength (UTS) of 1407 MPa, while 6Al steel exhibited extremely high total elongation (TE) of 65%. The superior ductility in 6Al steel is attributed to cumulative contribution of transformation induced plasticity (TRIP) effect and twinning induced plasticity (TWIP) effect. The increase in soft δ-ferrite phase with low microhardness led to increase in TE and decrease in UTS and work hardening rate.