Regulation of Finishing Cooling Temperatures on Microstructure and Comprehensive Mechanical Properties of Microalloyed Weathering Steel in Thermo‐Mechanical Control Process

A Gleeble‐3500 thermo‐mechanical simulator was employed for this study. The effects of finishing cooling temperatures (450/500/550/600 °C) on the microstructural evolution and mechanical properties of a novel V–Ti–N microalloyed high‐heat‐input weathering steel were investigated. The results show that with the increase of finishing cooling temperature, the proportion of polygonal ferrite (PF) increases, the fraction of granular bainitic ferrite decreases markedly, while the proportion of acicular ferrite increases slightly. The area fraction and size of M/A constituents increase, and the dislocation density reduces. Higher finishing cooling temperature causes microstructure coarsening. It diminishes dislocation substructures and decreases the strength and low‐temperature impact toughness. However, the increase in PF and coarsening of M/A constituents enhance the strain‐hardening capacity, slowing down the reduction in tensile strength, lowering the yield ratio, and improving the elongation after fracture. Based on the comprehensive performance evaluation, controlling the finishing cooling temperature at 500–550 °C achieves a good balance between strength, ductility, toughness, and yield ratio, resulting in excellent comprehensive mechanical properties. This study provides important theoretical and practical references for the preparation of high‐performance microalloyed high‐heat‐input steel by thermo‐mechanical control process.