Ultra-high strength steel M54 has been considered as promising candidates for structural applications in spacecraft and aircraft, because of its excellent static and dynamic characteristics. Numerical simulation is widely accepted as an effective way to help understand the dynamic response to structures under impact loadings. In this study, the Johnson-Cook (J-C) constitutive parameters and failure parameters used in ANSYS were accurately determined by fitting static and dynamic experimental data. Based on the obtained experimental results, the good combination of ultra-high strength and good elongation under quasi-static condition was ascribed to its special chemical composition, the microstructure of ultrafine lath martensite with high dislocation density, ultra-high martensite content, uniform distribution of nano-sized M₂C carbides and the existence of reverted austenite films. The dynamic compressive properties at high strain rates were investigated systematically by split Hopkinson pressure bar (SHPB) system. A remarkable strain rate strengthening effect came into evident on flow stress of the steel. The dynamic strengthening mechanisms were considered as fine-grain strengthening, substructure strengthening, and dislocation strengthening. Also, adiabatic shear behaviors of the steel under dynamic compressive tests were investigated. The results demonstrated that the strain rate was a key basis to judge stability of the M54 steel under impact loading. Recrystallization mechanism was responsible for the appearance of fine equiaxed grains within adiabatic shear bands (ASBs). The evolution of the ASBs was simultaneously revealed. The obtained experimental results and established J-C constitutive model could enhance the scientific understanding of dynamic mechanical behaviors of the M54 steel and provide reliable constitutive parameters for better guiding relevant engineering applications.

超高强度钢 M54 因其出色的静态和动态特性而被认为是航天器和飞机结构应用的有希望的候选材料。数值模拟被广泛认为是帮助理解冲击载荷下结构的动态响应的有效方法。在这项研究中，通过拟合静态和动态实验数据，准确确定了 ANSYS 中使用的 Johnson-Cook (JC) 本构参数和失效参数。实验结果表明，准静态条件下超高强度和良好延伸率的良好结合归因于其特殊的化学成分、高位错密度的超细板条马氏体显微组织、超高马氏体含量、均匀分布纳米级M₂C碳化物和还原奥氏体膜的存在。采用分裂式霍普金森压杆（SHPB）系统系统地研究了高应变率下的动态压缩性能。对钢的流变应力有显着的应变率强化效果。动态强化机制被认为是细晶强化、亚结构强化和位错强化。此外，还研究了钢在动态压缩试验下的绝热剪切行为。结果表明，应变率是判断M54钢在冲击载荷下稳定性的关键依据。再结晶机制是导致在绝热剪切带 (ASB) 内出现细等轴晶粒的原因。同时揭示了 ASB 的演变。