Railway axles, which are an important component of railway vehicles, are generally manufactured using high-speed forging processes. To investigate the microstructure evolution and flow behavior during forging processes, a series of isothermal hot compression and heating tests were conducted in the temperature range of 900–1200 °C and strain rate range of 0.01–20 s⁻¹. A strain-compensated Arrhenius constitutive relationship was identified for 25CrMo4 steel, and microstructure evolution kinetics, comprising dynamic recrystallization, metadynamic recrystallization, static recrystallization, and grain growth, were determined. A coupled thermomechanical–metallurgical numerical model was established for the high-speed forging of 25CrMo4 steel axles by using the TRANSVALOR Forge software package. The grain size evolution during the multipass high-speed forging process was predicted, and a full-scale axle was fabricated through high-speed forging to verify the predicted results. The predicted and experimentally observed grain sizes had good agreement. Finally, a series of geometric constraints are proposed for the design of round anvils. The reliability and applicability of the proposed constraints were validated by considering the surface quality and microstructure requirements as well as the forming force during chamfering. The results indicated that the proposed constraints can suitably guide the design of anvils for high-speed forging processes.

铁路车轴是铁路车辆的重要组成部分，通常使用高速锻造工艺制造。为了研究锻造过程中的组织演变和流动行为，在900–1200°C的温度范围和0.01–20 s ^-1的应变速率范围内进行了一系列等温热压缩和加热测试。确定了25CrMo4钢的应变补偿Arrhenius本构关系，并确定了包括动态再结晶，亚动态再结晶，静态再结晶和晶粒长大的微观组织演化动力学。使用TRANSVALOR Forge软件包，建立了用于25CrMo4钢轴高速锻造的热机械-冶金耦合数值模型。预测了多道次高速锻造过程中的晶粒尺寸演变，并通过高速锻造制造了一个全尺寸轴，以验证预测结果。预测和实验观察到的晶粒尺寸具有良好的一致性。最后，针对圆砧设计提出了一系列几何约束。通过考虑表面质量和微观结构要求以及倒角过程中的成形力，验证了所提出约束条件的可靠性和适用性。结果表明，提出的约束条件可以适当指导高速锻造过程中的砧座设计。