Production of Ultrahigh-Strength and High-Ductility TWIP Steel by Precipitation of beta-Mn during Large Deformation during Warm-Rolling

Herein, twinning-induced plasticity (TWIP) steel having large deformation is rolled at different rolling temperatures to improve the tensile strength and retain a certain plastic deformation capacity. Based on X-ray diffraction and transmission electron microscope analysis, beta-Mn is found as the precipitate at the grain boundary during the warm-rolling process (500-650 degrees C). To investigate the impact of beta-Mn on the tensile properties, the microstructure of the TWIP steel rolled at the temperature value of 600 degrees C is observed by carrying out electron backscatter diffraction and scanning electron microscope measurements. The intergranular beta-Mn phase can help the material to accumulate geometric nec-essary dislocation (GND) density, inhibit crack propagation, as well as improve the strength and plasticity of the material. Once TWIP steel is warm-rolled above the temperature value of 600 degrees C, and serrated flow appears in the tensile process, which is also conducive to improving the material properties.