高氮不锈钢滚轮滚针轴承外圈动载失效原因分析

Dynamic Load Failure Analysis of High Nitrogen Stainless Steel Tracd & Needle Roller Bearing Outer Ring

国内某轴承厂开发某型号滚轮滚针轴承,在动载试验过程中出现外圈开裂失效的问题,针对该问题进行分析。采用金相显微镜、维氏硬度计、扫描电镜等检测分析手段,从多个方面分析轴承失效的原因。结果表明:锻车滚轮滚针轴承金相组织中的网状碳化物存在,大大增加了材料脆性,使得外圈在轴承运转中、外力作用下快速脆性开裂;从断口形貌分析,开裂断口处是以脆性断裂为主、塑性断裂为辅;从扫描电镜EDS能谱分析知,轴承外圈基体和二次析出相中含氮化合物大量流失导致的氮元素含量过少,是造成其脆性断裂的主要原因。因此,滚轮滚针轴承外圈开裂失效原因为网状碳化物存在与氮元素含量流失所引起的脆性断裂。

The problem of outer ring cracking and failure of tracd&needle roller bearing developed by a bearing factory in China was analyzed.By means of metallographic microscope,Vickers hardness tester and scanning electron microscope,the causes of bearing failure were analyzed from many aspects.The results show that the presence of reticulated carbides in the metallography of tracd&needle roller bearing of forging wheel greatly increases the brittleness of the material and makes the outer ring brittle crack rapidly under the action of external force during the operation of the bearing.From the fracture morphology analysis,brittle fracture is the main fracture,and plastic fracture is the secondary fracture.According to EDS analysis of scanning electron microscope,the main reason of brittle fracture of bearing outer ring is that the content of nitrogen element is too little,which lead by the loss of nitrogen compounds in the matrix and secondary precipitated phase.In conclusion,the cracking failure of the outer ring of tracd&needle roller bearing is caused by the existence of reticulated carbides and the loss of nitrogen content.