Effects of annealing temperature on the microstructure and properties of the 25Mn-3Si-3Al TWIP steel

Microstructures and mechanical properties of the 25Mn twinning induced plasticity (TWIP) steel at different annealing temperatures were investigated.The results indicated that when the annealing temperature was 1000℃, the 25Mn steel showed ex-cellent comprehensive mechanical properties, the tensile strength was about 640 MPa, the yield strength was higher than 255 MPa, and the elongation was above 82%.The microstructure was analyzed by optical microscopy (OM), X-ray diffraction (XRD), and transmission electron microscopy (TEM).Before deformation the microstructure was composed of austenitic matrix and annealing twins at room temperature; at the same time, a significant amount of annealing twins and stacking faults were observed by TEM.Mechanical twins played a dominant role in deformation and as a result the mechanical properties were found to be excellent.