关键词: 车轮钢, 热变形, 热处理, 组织, 力学性能

Abstract: ER8 wheel steels with different microstructures were obtained based on 12 kinds of thermomechanical processes, and their tensile properties were compared. The results indicate that thermal deformation at 950 ℃ significantly increases the size of pearlite zone and proeutectoid ferrite compared to deformation at 850 ℃ and 900 ℃. Under a given thermal deformation temperature, heat treatment at 700 ℃ has little effect on the microstructure, whereas when the heat treatment temperature exceeds 800 ℃, the volume fraction of proeutectoid ferrite decreases rapidly while its grain size reduces gradually. The analysis of the tensile properties reveals that, under a given thermal deformation temperature, heat treatment at 700 ℃ reduces the residual stress introduced during thermal deformation, leading to decreased strength and increased ductility. By further increasing the heat treatment temperature, the ER8 wheel steel generally exhibits higher strength and lower ductility, which is associated with the reduction in ferrite content and the increase in pearlite content. The ER8 wheel steel achieves the highest strength along with good ductility under the process of thermal deformation at 850 ℃ followed by heat treatment at 800 ℃, with a yield strength of 595 MPa, a tensile strength of 920 MPa, and a total elongation at break of 19%.

Key words: wheel steel, thermal deformation, heat treatment, microstructure, mechanical properties