某批次激冷铸铁HT300CrMoCu汽车凸轮轴装配时,近1/4的凸轮轴在中间轴颈处发生断裂,采用宏观、微观对凸轮轴进行了理化检测,并对凸轮轴的铸造工艺进行分析。结果表明,凸轮轴致裂的原因首先是由于Cr含量超标,强烈阻碍铸铁的石墨化,形成合金碳化物;再就是冬天气温下降快,浇注温度低,冷铁未作及时调整,引起凸轮部分全白口,轴颈也出现了白口组织。通过控制合金成分、浇注温度、孕育处理、过热温度和保温时间、冷铁的尺寸等因素,来控制石墨的形成,改善和提高凸轮轴的性能。 A batch of chilled cast iron HT300CrMoCu car camshaft assembly, nearly 1/4 of the camshaft in the middle of the journal fracture occurs, the use of macro and micro camshaft physical and chemical testing, and camshaft casting process analysis. The results show that the reason of camshaft fracture is firstly that the content of Cr exceeds the limit, which strongly impedes the graphitization of cast iron and forms the alloy carbides. Thirdly, the temperature drops rapidly in winter and the pouring temperature is low. White mouth, neck also appeared in white tissue. By controlling the alloy composition, pouring temperature, inoculation, overheating temperature and holding time, chill iron size and other factors, to control the formation of graphite to improve and improve the performance of the camshaft.