Prior Warm Deformation Dependence on Microstructural Evolution and Tensile Properties of a High-Mn Steel

The thermally and deformation-induced phase transformation behaviors of high-Mn transformation-induced plasticity (TRIP) steel are complicated when there are two unstable phases (austenite and epsilon-martensite) in the microstructure. To study prior warm deformation dependence on microstructural evolution and tensile properties, an austenite/epsilon-martensite dual-phase high-Mn TRIP steel was subjected to different amounts of warm deformation. The work-hardening behavior of warm deformed steel was divided into three stages and illustrated by microstructural characterization after warm deformation and tensile fracture. The results showed that both planar glide and cross slip occurred during warm deformation of austenite, and epsilon-martensite, and microbands formed on the close-packed planes having higher Schmid factors. During tensile deformation at room temperature, the work-hardening exponents were associated with the dislocation slip and TRIP effect. The yield and ultimate tensile strengths of steel were increased, but the ultimate elongation was decreased with increasing strain of the prior warm deformation.