Cu元素合金化可以提高低碳马氏体不锈钢的力学性能，但其对该材料耐腐蚀性能的影响尚没有一致的认识。本工作采用SEM、XRD、TEM、APT以及电化学测试等手段研究了添加3%Cu (3Cu)对低碳马氏体不锈钢0Cr13Ni4Mo显微组织及耐腐蚀性能的影响，并与不含Cu不锈钢进行了对比分析。结果表明，经过1050℃固溶处理后，Cu均匀地分布在板条马氏体基体上；400℃回火后，Cu形成了极小的纳米团簇，其中偏聚了大量的Fe原子等；500℃回火后，Cu纳米团簇长大为尺寸为5~10 nm的富Cu析出相，核心处主要偏聚Cu原子，且与基体处于共格关系，而碳化物则由富Fe的纳米团簇生长成富Cr的析出相。3Cu低碳马氏体不锈钢经过500℃回火后表现出优异的耐腐蚀性能，这是因为富Cu析出相的长大过程中伴随着向周边基体排出Cr原子，减少了由富Cr碳化物造成的贫Cr区，从而降低了3Cu低碳马氏体不锈钢的腐蚀敏感性。

Low-carbon martensitic stainless steel 0Cr13Ni4Mo is widely used in hydraulic turbine runners, oil and gas storage, high-pressure pipes in power generation, and other fields owing to its high strength, good corrosion resistance, and good welding properties. However, to enhance its performance under different environments, there is a need to improve its strength and corrosion resistance. Previous studies have found that adding Cu to 0Cr13Ni4Mo steel enhances its strength through the formation of Cu-rich precipitation. However, the impact of Cu on the corrosion behavior of the 0Cr13Ni4Mo steel is not yet well understood. This study aims to investigate the effect of adding 3%Cu (mass fraction) on the microstructure and corrosion resistance of low-carbon martensitic stainless steel 0Cr13Ni4Mo using various techniques such as SEM, XRD, TEM, APT, and electrochemical testing. The results show that after solution treatment at 1050^oC, Cu is uniformly distributed on the lath martensite matrix. After tempering at 400^oC, Cu forms minute nanoclusters with a large number of Fe atoms segregated. On the other hand, tempering at 500^oC leads to the growth of Cu-rich precipitates with a size of 5-10 nm, where Cu atoms are mainly segregated at the core of the precipitates and are in a coherent relationship with the martensitic matrix. Carbides grow from Fe-rich nanoclusters to Cr-rich precipitates during the tempering process. The addition of 3%Cu to low-carbon martensitic stainless steel shows excellent corrosion resistance after tempering at 500^oC. This may be due to the emission of Cr atoms to the surrounding matrix during the growth of Cu-rich precipitates, which reduces the Cr-depleted zone caused by Cr-rich carbides in the matrix, thus reducing the corrosion sensitivity of 0Cr13Ni4Mo martensitic stainless steel with 3%Cu addition. These findings provide a better understanding of the role of Cu-rich precipitates on the corrosion performance of low-carbon martensitic stainless steels and provide guidance for the design of corrosion resistant steels.