400℃ 高周疲劳下 TC17 超声冲击强化表面状态演化规律研究

Based on UIT experiments, surface State measurement and tension-tension high cycle fatigue tests at 400 °C, the evolution laws of surface roughncss, surface morphology, residual stress, microhardness, and microstrueture of TC17 alloy were investigated. Results show that, compared with the surface states of the UIT processed speeimen, after lh heating treatment at 400 °C, the value of surface roughncss Ra increases from 0.46 µm to 0.67 µm, the surface microhardness decreases from 630 HV0.025 to 450 HV0.025, the surface compressive residual stress decreases from —640 MPa to — 525 MPa, the maximum value of compressive residual stress decreases from —1088 MPa to —776MPa, and the depth of plastic deformation layer decreases from 20 µm to 13 µm. After fatigue failureof the speeimen at 400 °C, the value of surface roughness Ra is as 1.22 ptm, the depth of compressive residual stress layer is as 70 µm, the depth of plastic deformation layer is as 9 µm, and the subsurface equiaxed a phase transforms into clongated Strips, the average grain arca increases from 11.8 µm² to 34 µm².