为了定量评价废旧件的疲劳损伤，以液压缸为研究对象，取其相应部位的材料制作标准拉伸试样，对试样进行疲劳拉伸试验，分析试样表面在不同疲劳损伤阶段的金属磁记忆信号，提出表征损伤程度的特征值与评估模型。结果表明，根据定位指标确定位置之后，再依据损伤程度评估指标，可对损伤程度进行判断。利用金属磁记忆检测技术可为废旧件损伤再制造的定量评价提供依据。

In order to quantitatively evaluate the fatigue damage of used parts, standard tensile test specimens were made from the same material as sample parts in the research object of hydraulic cylinder. After fatigue tensile tests on the specimens, the surface metal magnetic memory signals were analyzed at different fatigue stages. The eigenvalues and evaluation model are proposed to characterize the degrees of damage. The results show that after determining the stress concentration location according to the positioning index, the degree of damage is estimated based on the evaluation index. Metal magnetic memory detection technology provides a fundamental method for the quantitative evaluation of re-manufacturing ability of fatigue damage of used parts.