When 17-4PH martensitic stainless steel serviced at 300 °C for long term in nuclear power plant, the thermal aging embrittlement and hardening will be significant. It will seriously affect the safety and economic operation of nuclear power plant. In this work, Three-Dimensional Atom Probe Technology (3DAPT) was used to characterize the element distribution, and the evolution of Cu-rich precipitate and Cr-rich precipitate with service time were analyzed. The results show that with the service time increasing, the number density and size of Cu-rich precipitate and Cr-rich precipitate in the material increase obviously, which leads to the increase of critical shear stress with dislocation. The main reason to hardening is the nucleation and growth of Cu-rich precipitates and Cr-rich precipitates, which the contribution of Cu-rich precipitates fits Russell-Brown model. The contribution of Cr-rich precipitates to hardening increases with the service time, and is greater than that of Cu-rich precipitates.

当17-4PH马氏体不锈钢在300°C下长期在核电站中使用时，其热时效脆化和硬化作用将很明显。它将严重影响核电站的安全和经济运行。在这项工作中，使用三维原子探针技术（3DAPT）来表征元素分布，并分析了富铜沉淀物和富铬沉淀物随使用时间的演变。结果表明，随着使用时间的增加，材料中富Cu沉淀物和富Cr沉淀物的数量密度和尺寸明显增加，这导致位错的临界剪切应力增加。硬化的主要原因是富铜沉淀物和富铬沉淀物的形核和生长，富铜沉淀物的贡献符合Russell-Brown模型。富铬沉淀物对硬化的贡献随着使用时间的增加而增加，并且比富铜沉淀物的贡献更大。