平衡轴承毂开裂分析

卡车上QT400平衡轴承毂在总装入库一段时间后开裂。通过对平衡轴承毂断口及金相组织观察，化学成分、拉伸性能及冲击性能测试，确定了平衡轴承毂开裂的模式及产生的原因。结果表明:平衡轴承毂为一次性脆性开裂，在平衡轴承毂生产过程孕育剂添加过多导致平衡轴承毂硅含量过高，脆性较大是导致平衡轴承毂开裂的主要因素。通过严格控制生产过程孕育剂添加量，使平衡轴承毂硅含量回到正常范围，冲击韧性明显提高，由此解决了平衡轴承毂的脆性开裂问题。

Cracking Analysis of Balance Bearing Hub

The balance bearing hub of a truck cracked at storage time after final assembly. To make sure the mode and causes of the cracking, the chemical component of balance bearing hub was tested. The fracture and microstructure of balance bearing hub were observed and the tensile property and impact property of balance bearing hub were also tested. The results indicate that the cracking mode of balance bearing hub is one-time brittle crack. The excessive addition of nucleating agent at productive process leads to high level of silicon content and large brittleness, which is the main factor of the cracking of balance bearing hub. Therefore we control strictly the addition of nucleating agent to limit the silicon content at balance bearing hub and the impact toughness improves obviously. We solve the brittle crack of balance bearing hub finally.