In a refinery factory, some alloy of an antifriction bearing bush of a feed water pump in the HRSG (heat recovery steam generator) fell off. The analysis of bearing bush alloy components, the microstructure,and the morphologies of pits and cracks were conducted. It turned out that the lead in the bearing bush alloy is in a higher level, while the copper is in a lower level. Then the primary crystal Cu6Sn5formed by copper and tin was rare and the SnSb with small density floated and segregated,which reduced the fatigue resistance of Bibbitt Metal. Under the action of several alternating loads,an oil wedge was formed when the lubricating oil infiltrated the microcracks on the bearing bush surface and unable to escape. The cracks expanded continuously and connected with each other, and the fatigue pitting hap-pened on the internal surface of the bearing bush. Finally,a large number of pits were formed and even a bulk of alloy fell off.%某炼油厂余热锅炉给水泵滚动轴承轴瓦合金发生脱落.对轴瓦合金成分、金相组织、凹坑及裂纹形貌等进行分析,结果发现轴瓦合金中铅含量过高,铜含量较低,铜与锡形成的初晶体Cu6Sn5偏少,密度较小的晶体SnSb上浮偏析,降低了巴氏合金的抗疲劳性能.在交变载荷的作用下,润滑油渗入轴瓦表面微细裂纹无法逸出而形成油楔,裂纹持续扩展并彼此连接,从而在轴瓦内衬表面发生疲劳点蚀,形成大量麻坑,甚至发生大块脱落.
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