关键词: TWIP钢, 退火温度, 超细晶, 屈服强度, 强塑积

Abstract: Effect of annealing temperature on the microstructure and mechanical properties of Cu-containing TWIP steel was studied using electron backscatter diffraction(EBSD), X-ray diffraction(XRD), scanning electron microscope(SEM), and mechanical testing. Thermodynamic calculations reveal that the stacking fault energy (SFE) of Fe-22Mn-0.6C-3Cu TWIP steel at room temperature is 27.95 mJ/m², indicating that the deformation is primarily dominated by twinning. The results show that as the annealing temperature decreases, the microstructure of the Cu-containing TWIP steel evolves from homogeneous coarse equiaxed grain to mixed microstructure of fine and ultrafine grains. Correspondingly, the yield strength and tensile strength increase, while the elongation decreases. Moreover, as the average grain size decreases, the onset of dynamic strain aging is delayed. The ultrafine-grained (UFG) Cu-containing TWIP steel, fabricated through multi-pass cold rolling followed by low-temperature short-time annealing (650 ℃×5 min), exhibits the optimal mechanical properties. The steel achieves a yield strength of 643 MPa, a tensile strength of 1104 MPa, an elongation of 78.5%, and a product of tensile strength and elongation of 86.4 GPa·%.

Key words: twinning induced plasticity(TWIP) steel, annealing temperature, ultrafine grain, yield strength, product of tensile strength and elongation