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

Abstract

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, β‐Mn is found as the precipitate at the grain boundary during the warm‐rolling process (500–650 °C). To investigate the impact of β‐Mn on the tensile properties, the microstructure of the TWIP steel rolled at the temperature value of 600 °C is observed by carrying out electron backscatter diffraction and scanning electron microscope measurements. The intergranular β‐Mn phase can help the material to accumulate geometric necessary 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 °C, and serrated flow appears in the tensile process, which is also conducive to improving the material properties.