目的 提高渗碳淬火轴使用寿命。方法 针对渗碳淬火轴关键部位孔口，采用超声冲击处理工艺对其进行表面强化处理，利用电子显微镜、硬度计结合有限元模拟对处理后的微观组织、硬度、残余应力等进行分析。结果 在孔口处理区，材料产生了明显的加工硬化，形成了梯度硬化层，硬化层厚度达到 80 μm，表层硬度约 60HRC。对超声冲击孔孔口部分的表面残余应力值进行测量，最小残余应力值为 374 MPa, 最大残余应力值为?530 MPa，采用上述超声冲击处理后，样品的残余应力平均值在?450 MPa。利用有限元模拟了孔口附近沿轴向深度的残余应力分布，其残余压应力层深约 1.4 mm，最大残余应力?891 MPa，疲劳危险点处的残余应力平均值约?760 MPa。轴孔边缘第三主应力基本上沿轴线方向。结论 通过超声冲击处理工艺对渗碳淬火轴孔口进行处理后，在孔角处形成硬化层，同时产生残余压应力，上述处理后可有效降低工作应力造成的疲劳载荷幅。

The work aims to improve the service life of carburied& quenched shaft. The hole on the key part of the carburied& quenched shaft was treated by ultrasonic impact. The microstructure, hardness and residual stress after treatment were analyzed by electron microscope, hardness tester and finite element simulation. The material became hardened obviously in the hole processing area and then formed the gradient hardening layerwhich reached the thickness of 80 μm including 60HRC surface hardness. The residual stress on the hole by ultrasonic impact was measured and the minim value was ?374 MPa and the maximum value was ?530 MPa. After the above ultrasonic impact treatment, the average residual stress of samplewas ?50 MPa. The finite element method was used to simulate the residual stress distribution of the depth along the axial, and the residual compressive stress layer depth was about 1.4 mm, the residual stress was ?891 MPa, and the average residual stress in the fatigue dangerous spot was about ?760 MPa. The third principal stress on the edge of the gear shaft near the hole was basically along the axis of the gear shaft. After the carburied& quenched shaft hole is treated by ultrasonic impact, the hardening layer is formed in the hole angle and the residual stress can be generated. Therefore, the above treatment can effectively reduce the fatigue load caused by the working stress.