油田作业刹车轮毂的失效分析

Failure Analysis of the Brake Hub of an Oil Field Working Machine

对辽河油田失效刹车轮毂进行了裂纹形貌、化学成分、机械性能及显微组织的检验、分析及讨论。结果表明,刹车轮毂的失效主要是由于热处理工艺不当造成的。一方面,热处理工艺不当无法彻底消除铸态组织的不利影响,结果使得铸件的塑、韧性指标大幅度降低;另一方面,热处理工艺不当使得铸造应力及机加工的残余应力无法彻底消除,这样加剧了裂纹的产生和扩展。建议在最终热处理前增加一道退火工序,通过细化晶粒,来消除网状铁素体和不均匀组织,进一步提高材料的力学性能。

Aiming to the failure phenomena of brake hub of Liaohe oil field, crack figures, chemistry composition, mechanical property, and metallographic structures were tested, analyzed and discussed. The results show that the failure of the brake hub is caused by the improper heat treatment operation. On the one hand, the improper heat treatment operation can not thoroughly remove the bad effects of cast structures and leads to tremendous reduction of the plasticity and toughness index. On the other hand, the improper heat treatment operation can not completely relieve the casting stress and remnant stress, and further enhances generation and expansion of cracks. A working procedure before the last heat treatment operation was suggested to be added. Through refining crystal grain, the reticular ferrite and heterogeneous structures are relieved, and further mechanical property of mate.rials can be improved.