马氏体时效钢以其超高的强度及优良的综合力学性能广泛应用于宇航结构钢、火箭发动机外壳等航空航天领域。 该材料可以通过在中等温度下进行时效处理析出纳米级的析出相来实现组织强化，具有超高强度、高延展性和高韧性。 不同钴含量对马氏体时效钢的时效组织具有较大影响，但目前钴元素在材料时效组织的作用机制目前仍存在争议，相关方面研究较少。 本文设计并制备了成分为 6%~12%( 质量分数 ) 钴含量的马氏体时效钢，并对其时效组织进行测试和表征。 实验结果表明，随着钴含量的升高，时效组织的马氏体板条宽度减小，位错密度升高，材料内部的纳米析出相由富 Mo 相逐渐转变为 Ni 3 Ti 相。

Maraging steel is widely used in aerospace applications such as aerospace structural steels and rocket engine casings, due to its ultrahigh strength and excellent comprehensive mechanical properties. The materials can be strengthened by precipitating nanoscale phases through aging treatment at moderate temperatures to achieve ultrahigh strength, high ductility and high toughness. Different cobalt contents have a great influence on the aging microstructure of maraging steels. However, the mechanism of cobalt in the microstructure of materials after aging treatment is still controversial at present, and there are fewer studies in this regard. In this paper, maraging steels with compositions ranging from 6% to 12%(mass fraction) cobalt content were designed and prepared, and the aging microstructures were tested and characterized. The results show that with increasing cobalt content, the martensite lath width of the aging microstructure decreases, the dislocation density increases, and the nano-precipitated phase in the material is gradually transformed from the Mo-rich phase to the Ni 3 Ti phase.