塑性变形在淬硬钢磨削白层形成中的作用机理

Action Mechanism of Plastic Deformation on the Grinding White Layer of Harden Bearing Steel

对淬硬轴承钢GCr15进行了磨削实验,采用热电偶和三向压电晶体测力仪测量了磨削温度和磨削力.通过X射线衍射仪对磨削表面残余奥氏体含量、马氏体亚晶粒尺寸以及微观应变进行了分析.通过有限元分析软件仿真计算了工件表面的接触应力和应变,讨论了塑性变形在磨削白层形成中的作用.结果表明:法向磨削力引起材料的强烈塑性变形和高接触应力;工件表面高的接触应力能降低材料相变温度,促进相变的发生;强烈的塑性变形能细化晶粒作用;磨削白层的厚度随着塑性变形的增加而增加,而其亚晶粒大小随塑性变形的增加而减小.

The grinding temperature and the grinding force were measured by using the thermocouple technique and 3-axis piezoelectric dynamometer in the grinding process of GCr15 harden steel. The residual austenite content, the subgrain size of the martensite and the micro-strain in the grinding surface were analyzed on the basis of X-ray diffraction （XRD） examinations of the microstructure. The contact stress and the plastic strain of the grinding surface were simulated hy using the finite Cement method （FEM）. The effect of the plastic deformation on the grinding white layer was discussed. The results have shown that intense plastic deformation and high contact stress can be brought about by the normal grinding force. High contact stress can reduce phase temperature, and plastic strain can refine crystal grain. The depth of white layer increases with the plastic strain and the crystal subgrain size decreases with the plastic strain.