表面激光硬化轴承的疲劳失效分析

Analysis on Fatigue Failure of GCr15 Steel Bearing by Laser Hardening

选用CO2激光器进行GCr15钢轴承滚道表面激光淬火处理试验,内圈硬化层深度可达到0.5 mm,外圈可达到0.45 mm。用金相显微镜、扫描电镜和X射线分析等现代测试技术对改性层的相组成及改性机理进行分析。结果表明,轴承表面的激光相变硬化可以产生具有较多残余奥氏体、细小碳化物以及过饱和的隐晶马氏体组织,从而提高轴承滚道表面的硬度。最后进行了轴承钢的接触疲劳性能试验。通过疲劳失效轴承表面的显微观察,验证了激光淬火套圈表面的疲劳失效形式仍为表层剥落。造成激光淬火套圈早期疲劳失效的主要原因是激光扫描开始与结束接口处没有完全对接上,以及硬化层深不均匀。

The laser surface hardening process of GCrI5 steel bearing inner and outer tings was tested by using CO2 continuous wave laser. A hardening depths of 0.50 mm （inner tings） and 0.45 mm （outer rings） were researched. The macromorphology and microstructure of the laser surface hardened layers were investigated by scanning electron microscopy （SEM）, optical microscopy and X-ray diffraction measurements. The results show that the laser transformation hardening can produce martensitic microstructure with more retained austenite and finer carbides to increase the hardness of the bearing surface. The fatigue properties of laser surface hardening GCrl5 steel bearing were studied. Bearing tings surfaces were examined by microscope after failure. It was identified by tests that the failure mode of bearing tings surfaces is surface spalling. The reason of early fatigue failure of laser surface hardening GCrl 5 steel bearing is no completely docking between the beginning and ending boundaries of the bearing tings and the unven hardeninlz layer depth.