汽车轮毂轴承的断裂失效分析

Fracture failure Analysis of Automobile Wheel Bearing

通过外观检查、成分测试、硬度测试、金相组织和扫描电镜观察等方法,对某品牌汽车3个轮毂轴承失效件进行分析,找出了造成轮毂轴承最终断裂失效的原因。结果表明,3种轮毂轴承的内圈和外圈的组织都符合JB/T 1255-2001标准的要求;1#轮轴轴承失效的原因是由于化学成分不合格和轴承内圈滚道的表面硬度较低;2#轮毂轴承的化学成分、硬度和组织都满足要求,失效原因在于密封性较差,而使得外圈滚道中外界硬度相对较高的颗粒落入滚道,造成磨损加剧;3#轮毂轴承外圈碳含量较低,使得外圈滚道表面硬度偏低,且由于润滑条件不好引起了粘着磨损,加剧了轴承的磨损,并最终造成失效。

The failure of three wheel bearings was analyzed by means of the appearance inspection,component testing,hardness testing,metallographic structure and scanning electron microscope.The results show that the microstructure of the three wheel bearing＇s inner ring and outer ring are in accordance with the requirements of JB/T1255-2001 standard.The failure of 1# wheel bearing is due to the unqualified chemical composition and the relatively low surface hardness of the bearing inner ring;the chemical composition,hardness and microstructure of 2# bearing meet the requirements,the failure reason is in poor sealing and the particles with relatively high external hardness outside outer ring fall into the raceway to cause wear increase;the carbon content of outer ring in 3# bearing is low making the outer ring raceway surface hardness lower,together with the bad lubrication condition to cause adhesion wear and eventually cause the failure.