亚稳态奥氏体304不锈钢在核电领域应用广泛，但易发生疲劳损伤而影响服役寿命，因此通过无损检测手 段评估其服役过程中的疲劳损伤至关重要。 本文采用X射线衍射、电子背散射衍射、硬度和磁性能测试手段，系统研究 了304 不锈钢在不同疲劳循环次数下的微观组织与维氏硬度和饱和磁化强度之间的关联性。 结果表明，随着疲劳循环 次数增加，304不锈钢由奥氏体相转变为马氏体相，且马氏体相含量不断增加；而位错密度在疲劳循环0~1周内增加后 基本不变。 在疲劳循环0~1周内，304不锈钢的维氏硬度由马氏体含量和位错共同决定；而在后续疲劳循环中，维氏硬 度增量仅与马氏体含量增加有关，此时二者呈线性关系。 304不锈钢的饱和磁化强度与钢中马氏体含量相关，且二者之 间也存在线性关系。

Metastable austenitic 304 stainless steel is widely used in the field of nuclear power, but it is prone to fatigue damage and affects the service life; thus, it is crucial to assess the fatigue damage during service via nondestructive testing meansmethods. The correlations among the microstructure, Vickers hardness, and saturation magnetization of 304 stainless steel under different fatigue cycles were investigated via X-ray diffraction, electron backscatter diffraction, hardness, and magnetic property testing. The experimental results show that with increasing number of fatigue cycles, 304 stainless steel transforms from the austenite phase to the martensite phase, and the martensite phase content continues to increase; the dislocation density increases rapidly during the fatigue process from 0 to 1 cycle and remains relatively constant thereafter. The martensite content and number of dislocations affect the Vickers hardness of 304 stainless steel during 0 to 1 cycle of the fatigue process; as the number of fatigue cycles further increases, the increase in the Vickers hardness is related to only the increase in the martensite content, and a linear relationship exists between them. The saturation magnetization of 304 stainless steel is associated with the martensite content in the steel, and there is also a linear relationship between the two.