稀土元素对半钢冲击疲劳性能的影响

Effect of Rare Earths on Impact Fatigue Property of Cast Semi-Steel

研究了稀土元素对半钢冲击疲劳性能的影响。采用金相显微镜、扫描电镜观察了经疲劳试验后半钢中碳化物的形貌、疲劳裂纹的萌生与扩展 ;测定了稀土含量与总裂纹的长度和裂纹扩展速率之间的关系曲线。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。当半钢中添加 0 .2 %RE及 960℃× 3h正火处理共同作用时 ,抗冲击效果最显著。

The effect of rare earth on impact fatigue property of cast semi steel was studied. The morphology of carbide, the appearance of fatigue crack forming and the fatigue crack propagating speed of cast semi steel were studied by means of optical microscope and scan electron microscope and the relation curves between the content of RE in cast semi steel specimen and the length, forming speed of fatigue crack were determined in impact fatigue test. The experimental results show that adding rare earth into cast semi steel can defer the time of forming fatigue crack, reduce the speed of crack propagating and increase the impact fatigue resistance. When normalizing is taken at 960 ℃×3 h after adding 0.2%RE, the best impact fatigue property is obtained, which is attributed to the variation morphology and the distribution of eutectic carbide network.