Mechanical properties of an Fe-30Mn-4Si-2Al alloy after rolling at different temperatures ranging from 298 to 1073 K

The microstructure evolution and associated changes of mechanical properties in an Fe-30Mn-4Si-2Al TRIP/TWIP steel subjected to rolling over a wide temperature range of 298-1073 K were studied. The extensive ε-martensite subdivides the initial coarse grains into nanoscale lamella structure after rolling at 298 K, with a high dislocation density. The elevating of rolling temperature changed the deformation microstructure from ε-martensite to deformation twins, as well as a decrease in dislocation density. The main emphasis is on the contribution of different plastic deformation mechanisms involved in the strengthening. Both ε-martensite and deformation twins have an impact on the strengthening by bringing about a Hall & Petch effect. However, dislocation gives more contribution during rolling at all the investigated temperatures. An interesting consequence of this observation is that the asynchronous synergy of deformation twins induced by warm rolling at 673 K and ε-martensitic transformation occurred at room temperature tensile deformation renders this material distinctly stronger with an improved work hardening rate.