32Cr3MoVE渗氮轴承钢的高应力滚动接触疲劳性能

High Stress Rolling Contact Fatigue Properties of 32Cr3MoVE Nitrided Bearing Steel

对采用双真空熔炼制备的32Cr3MoVE轴承钢进行表面渗氮处理,利用滚动接触疲劳试验机在4.5GPa高应力下研究其滚动接触疲劳性能,分析其滚动接触疲劳破坏机制。结果表明:试验钢的有效渗氮层深度为350μm,随距表面距离的增大,渗氮层残余压应力呈先增大后减小趋势,距表面300μm处的残余压应力最大,为610 MPa;渗氮层中存在沿晶界分布的白色脉状组织;利用双参数Weibull分布计算得到其滚动接触疲劳特征寿命、额定疲劳寿命、中值疲劳寿命分别为3.040×10~8,0.357×10~8,2.083×10~8周次;试验钢的滚动接触疲劳破坏模式包括表面起裂和次表面起裂两种,表面起裂试样剥落坑的平均直径及深度均明显大于次表面起裂试样的;表面起裂试样沿表面点蚀坑或划痕处起裂,次表面起裂试样在长时间循环接触应力作用下,次表面材料性能退化,导致裂纹萌生。

Surface nitriding treatment was conducted on 32 Cr3 MoVE bearing steel prepared by double vacuum melting process.The rolling contact fatigue performance was studied under the high stress of 4.5 GPa by rolling contact fatigue testing machine,and the failure mechanism of rolling contact fatigue was analyzed.The results show that the effective nitriding layer depth of the test steel was 350μm;the residual compressive stress in the nitriding layer increased and then decreased with the increase of distance from the surface,and had the largest value of 610 MPa at 300μm distance from surface.The white vein structure distributing along the grain boundaries appeared in the nitriding layer.The rolling contact fatigue characteristic lifetime,rated fatigue lifetime and median fatigue lifetime were 3.040×10~8,0.357×10~8,2.083×10~8 cycles,respectively,calculated by two-parameter Weibull distribution.The rolling contact fatigue failure modes of the test steel included surface crack initiation and subsurface crack initiation,and the average diameter and depth of peeling pits in surface crack initiation sample were significantly larger than those of subsurface crack initiation sample.Surface crack initiation sample cracked along pits or scratches on the surface;the subsurface material properties of subsurface crack initiation sample degraded under the action of prolonged cyclic contact stress,resulting in crack initiation.