磨削加工对GCr15SiMn轴承钢表面组织性能的影响

采用扫描电镜,电子背散射衍射、X射线衍射、显微硬度计及三维表面轮廓仪等对磨削加工后的GCr15SiMn轴承钢的显微组织、硬度、残余应力及物相进行了研究。结果表明:磨削后GCr15SiMn轴承钢表面的硬度远高于基体,并且残留奥氏体发生分解,表面呈现压缩残余应力。试样表层组织存在由于塑性变形引起的几何必须位错密度(GND)增加的现象,这是轴承钢表面硬度上升的主要原因。将轴承服役过程以及磨削加工后的组织性能变化进行对比,发现有相似之处。磨削加工引起的表层变化可能是诱发裂纹在表面萌生的原因。

Effect of grinding on surface microstructure and properties of GCr15SiMn bearing steel

Microstructure, hardness, residual stress and phase of GCr15 SiMn bearing steel after grinding were studied by means of scanning electron microscopy, electron backscatter diffraction technique, X-ray diffraction, microhardness tester and three-dimensional surface profile instrument. The results show that the hardness of the surface of the GCr15 SiMn bearing steel after grinding is much higher than that of the matrix, and the residual austenite is decomposed and the surface exhibits compressive residual stress. There exists the increase of geometrically necessary dislocation(GND) due to plastic deformation in the surface of the sample, which is the main reason of the increase of the surface hardness of the GCr15 SiMn bearing steel. The change of the microstructure and properties of the GCr15 SiMn bearing steel during service process and grinding are compared, and the similarities are found. The change of microstructure and properties of surface layer caused by grinding may be the cause of crack initiation on the surface.