Microstructural evolution and deformation behavior in the Fe-(6, 8.5)Mn-3Al-0.2C TRIP steels

We have studied here the microstructural evolution and deformation behavior in two hot-rolled Fe-6Mn-3Al-0.2C (6Mn steel) and Fe-8.5Mn-3Al-0.2C (8.5Mn steel) transformation induced plasticity (TRIP) steels. Excellent combination of mechanical properties including total elongation (TEL) of 39.3%, ultimate tensile strength (UTS) of 1112 MPa and UTS×TEL of 43.7 GPa% were obtained in 8.5Mn steel subjected to intercritical hardening at 750 °C and tempering at 200 °C. The increase in the Mn-content in the experimental steel led to increase in the volume fraction of austenite and change in austenite morphology. Non-uniform Mn distribution in austenite with varied morphology resulted in different degree of austenite stability and led to discontinuous TRIP effect, contributing to the best combination of mechanical properties in 8.5Mn-750 steel.