ZG45铸钢轴端套在制造过程中发现裂纹,采用化学成分分析、宏观及金相检验、扫描电镜分析等方法, 对轴端套裂纹产生原因进行了分析。结果表明: 由于冶炼浇注工艺不当, 硅、锰元素含量偏低等原因, 导致铸件结晶组织粗大及最后凝固区域低熔点非金属夹杂物沿晶界分布, 使晶界成为薄弱环节, 在随后加工过程的热应力作用下铸件沿晶开裂并扩展至表面。

Cracks were found on ZG45 cast steel axle sleeves surface during manufacturing, and cracks formation causes were analyzed by means of chemical compositions analysis, macro examination, metallographic examination and scanning electron microscope analysis, etc. The results show that as a result of inappropriate smelting and casting procedure, the content of silicon and manganese in the steel was below the standard requirement, which led to coarse grains forming in the steel and low-melting-pointed non-metallic inclusions gathering along the grain boundaries at the last solidified areas. Therefore, the grain boundaries became the weak positions and cracks formed and extended along the grain boundaries under action of the following thermal stress.