稀土变质及热处理对耐磨铸铁冲击疲劳性能的影响

采用金相显微镜、扫描电镜观察了经冲击疲劳试验后耐磨铸铁中碳化物的形貌、疲劳裂纹的萌生与扩展,测定了稀土含量及加热温度与裂纹的长度和裂纹扩展之间的关系曲线,在此基础上探讨了稀土变质及热处理对耐磨铸铁冲击疲劳性能的影响.结果表明: 稀土能推迟裂纹萌生的时间,降低裂纹扩展速率,提高其冲击疲劳抗力.当稀土与热处理共同作用时,效果更显著.其原因主要归于网状共晶碳化物形态与分布的改变.

Effect of Rare Earth Modification and Heat Treatment on Impact Fatigue Property of Wear Resistant White Cast Iron

The morphology of carbides, as well as the generation and propagation of fatigue cracks in wear-resistant white cast iron after impact fatigue test were observed by means of optical microscopy and scanning electron microscopy, and the relationship between the content of RE (rare earths) in the wear-resistant white cast iron and the heating temperature as well as the length and propagation speed of the fatigue cracks were determined. Based on the obtained results, the effect of RE modification and heat treatment on the im- pact fatigue property of the wear resistant-white cast iron was further studied. The experimental results show that adding RE into white cast iron can defer the time for the generation of fatigue cracks, reduce their propagation speed and increase the impact fatigue resistance . The aforesaid effect is more noticeable in the case of combination of RE modification and heat treatment , which can be attributed to the variation of morphology and the distribution of eutectic carbide network.