The microstructure, tensile strength, high-cycle fatigue property and corresponding damage mechanisms of compacted graphite iron at room temperature (25 °C), 400 °C and 500 °C, were investigated. It is found that the fatigue strength increases at first and then decreases with the increase of the testing temperature. At 25 °C, the fatigue crack mainly initiates from graphite debonding and propagates along the graphite clusters. At 400 °C, the fatigue crack initiation is influenced by oxidation; the fatigue strength may be improved by dynamic strain aging. At 500 °C, the oxidation becomes more serious and the oxide layer accelerates the crack to propagate along the matrix. At the same time, the phenomenon of grain boundary softening, one of the reasons resulting in the reduction of fatigue strength, appears. Then, the model of damage mechanism was proposed according to the propagation behavior of fatigue crack at high temperatures, and the quantitative relationship between the fatigue strength and the ratio of the interphase corrosion depth to the critical crack length was established. This investigation may enrich the fundamental understanding on the damage mechanism of compacted graphite iron.

研究了压实石墨铁在室温（25°C），400°C和500°C下的组织，拉伸强度，高周疲劳性能以及相应的破坏机理。发现随着测试温度的升高，疲劳强度首先增加，然后降低。在25°C时，疲劳裂纹主要是由石墨脱胶引起的，并沿着石墨团簇扩展。在400°C时，疲劳裂纹萌生受到氧化的影响。通过动态应变时效可以改善疲劳强度。在500°C时，氧化会变得更加严重，并且氧化层会加速裂纹沿基体传播。同时，出现晶界软化现象，这是导致疲劳强度降低的原因之一。然后，根据高温下疲劳裂纹的扩展行为，提出了损伤机理模型，建立了疲劳强度与相间腐蚀深度与临界裂纹长度之比的定量关系。这项研究可以丰富对压实石墨铁的损伤机理的基本认识。