Formation mechanism of surface metamorphic layer and influence rule on milling TC17 titanium alloy

To control the surface metamorphic layer and improve the performance of the workpiece, a combination of measurement and simulation is employed to obtain the force and temperature fields in TC17 milling. Based on the thermo-mechanical coupling, the formation mechanism of the surface metamorphic layer is analyzed. In addition, the influence of parameters on the surface characteristics is also studied. The results show that the milling force varies from 58.39 to 170.7 N, the temperature effect layer increases from 102 μm to 210 μm, and the effective strain layer increases from 38 μm to 145 μm within the experiment parameters. The thermal-mechanical coupling has a significant effect on residual stress. The surface compressive residual stress varies from − 206 to − 314 MPa, and the residual stress layer depth fluctuates by 30 μm. With the enhancement of thermal-mechanical coupling, the microhardness fluctuation does not exceed 20HV_0.025, and the maximum microhardness can reach 384HV_0.025. Moreover, the microhardness effected layer remains at 40 μm regardless of parameters enhanced, revealing that microhardness is insensitive to the process parameters. The plastic deformation layer depth alternates between 17 and 28 μm, indicating that it is little affected by thermal-mechanical coupling. Finally, the established model can accurately predict surface roughness and residual stress.