关键词: TC17钛合金, 超声冲击强化, 表面状态, 高周疲劳, 演化规律

Abstract: Based on UIT experiments, surface state measurement and tension-tension high cycle fatigue tests at 400 ℃, the evolution laws of surface roughness, surface morphology, residual stress, microhardness, and microstructure of TC17 alloy were investigated. Results show that, compared with the surface states of the UIT processed specimen, after 1h heating treatment at 400 ℃, the value of surface roughness 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 -776 MPa, and the depth of plastic deformation layer decreases from 20 μm to 13 μm. After fatigue failure of the specimen at 400 ℃, the value of surface roughness Ra is as 1.22 μm, 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 α phase transforms into elongated strips, the average grain area increases from 11.8 μm2 to 34 μm2.

Key words: TC17 titanium alloy, ultrasonic impact treatment(UIT), surface state, high-cycle fatigue, evolution law