42CrMoA钢主轴内部夹杂缺陷分析与控制

42CrMoA钢主轴在锻造后无损检测时发现内部有缺陷。采用宏观分析、扫描电镜观察、能谱分析、金相分析、化学成分分析、力学性能分析等方法对主轴缺陷的性质、成因和对主轴的影响进行了分析。结果表明:主轴内部缺陷为外来夹杂物,主要包含Al、Si、Ti、Ca、Mg、Na、K等元素的氧化物,主要为钢液或渣液冲刷熔蚀脱落的耐火材料形成的复合夹杂物,以及少量保护渣、炉渣,这些外来夹杂物集中分布在主轴的心部,其他位置的化学成分、内生夹杂物、金相组织、力学性能检测结果正常。通过优化浇铸工艺、挡渣设计等措施可以减少外来夹杂物。

Analysis and control of inclusion defects in 42CrMoA steel shaft

The internal defects were found during non-destructive testing in one 42CrMoA steel shaft after forging. The methods including macroscopic analysis， scanning electron microscope （EDS） observation， energy dispersive spectrum analysis （EDS）， metallographic examination， chemical composition analysis and mechanical property analysis were used to analyze the property and causes of defects as well as the influence on the shaft. The results showed that the defects inside of shaft were foreign inclusions， which mainly included the oxides of Al， Si， Ti， Ca， Mg， Na and K. The inclusions were composed of a small amount of furnace slag and protective slag as well as a large amount of composite inclusions which were formed by refractory materials from molten steel or liquid slag flushing. These foreign inclusions were concentratedly distributed in the center of the shaft. The testing results of chemical composition， endogenous inclusion， metallographic structure and mechanical property in other positions were normal. The foreign inclusions could be reduced by the measures such as optimizing the casting procedures and designing slag trap.