车削加工工艺对EA4T车轴钢疲劳性能的影响

摘要

对不同工艺车削加工的EA4T车轴钢进行旋转弯曲疲劳试验,研究了车削加工工艺对该钢疲劳性能的影响.结果表明:在不同车削加工工艺下,试验钢轴向残余压应力的最大值与最小值相差50 MPa,周向残余拉应力的最大值与最小值相差25 MPa,车削加工工艺对残余应力的影响不大;不同车削加工工艺下试验钢表面粗糙度均小于0.8 μm,且表面粗糙度的最大值与最小值相差0.15 μm,车削加工工艺对表面粗糙度的影响不大;当表面粗糙度小于0.8 μm 时,车削加工工艺对疲劳寿命的影响不大;疲劳断口均分为裂纹源区、裂纹稳态扩展区和瞬断区,且均只有一个裂纹源,疲劳裂纹都是在表面较深车痕的根部萌生并向内扩展.%The rotary bending tests of EA4T axle steel machined with different turning processes were conducted,and the effect of turning process on fatigue behavior of the EA4T axle steel was studied.The results show that the difference between the maximum and minimum residual compressive stresses of the tested steel was 50 MPa and that of the residual tensile stresses was 25 MPa under different turning processes.The turning process had little influence on the residual stress.The surface roughness of the tested steel under different turning processes was less than 0.8 μm and the difference between the maximum and minimum surface roughness was 0.1 5 μm.The turning process had little effect on the surface roughness.When the surface roughness was less than 0.8 μm,the impact of the turning process on the fatigue life was limited.The fatigue fracture consisted of crack source region, crack stable expansion region and transient region,and only one crack source existed.The fatigue cracks were generated in the root of the deep turning marks and extended to the inside of the tested steel.