冷轧对G20CrNi2MoA渗碳轴承钢组织演变与耐磨性的影响

采用电子背散射衍射分析(EBSD)、扫描电镜(SEM)、X射线能谱分析(EDS)等方法研究了冷轧对G20CrNi2MoA渗碳轴承钢微观组织演变规律和耐磨性的影响。结果表明:冷轧能够细化原材料晶粒;当冷轧变形量由0%增加到30%时,经二次淬火后,表层碳化物面积分数由4.38%增加到5.99%,碳化物平均粒径由0.15 μm降低到0.13 μm;经二次低温回火后,表层约0.9 mm渗碳层深范围内碳含量梯度和显微硬度梯度得到提高,平均摩擦因数由0%的0.489降低到30%变形量下的0.346,磨损率由27.2×10^-6 mm³·N^-1·m^-1降低到9.1×10^-6 mm³·N^-1·m^-1。表明材料经30%冷轧变形后,由于表层碳化物的面积分数和硬度得到提高,磨粒磨损和疲劳磨损逐渐减轻,使耐磨性得到提高。

Effect of cold rolling on microstructure evolution and wear resistance of G20CrNi2MoA carburized bearing steel

Effect of cold rolling on the microstructure evolution and wear resistance of G20CrNi2MoA carburized bearing steel was studied by means of electron backscattered diffraction (EBSD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that the cold rolling can refine the grain size of the raw materials. When the cold rolling reduction increases from 0% to 30%, the area fraction of carbides increases from 4.38% to 5.99% and the average diameter decreases from 0.15 μm to 0.13 μm after the secondary quenching. After the secondary low-temperature tempering, the gradients of both the carbon content and the microhardness are increased within about 0.9 mm depth of the surface carburized layer, the average friction coefficient decreases from 0.489 to 0.346 when the cold rolling reduction increases from 0% to 30%, and the wear rate also decreases from 27.2×10^-6 mm³·N^-1·m^-1 to 9.1×10^-6mm³·N^-1·m^-1. It indicates that the abrasive wear and fatigue are decreased gradually due to the increasing of area fraction of carbides and microhardness of the top surface after 30% cold rolling reduction, thus the wear resistance of the materials increases.