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使用Nd:YAG纳秒激光器分别在试样表面温度为20、100、200、300以及400℃下对TC4钛合金狗骨状拉伸试样进行激光喷丸表面强化,然后使用疲劳试验机在高周疲劳条件下对试样进行残余应力释放测试与疲劳寿命测试,并使用热场发射扫描电镜研究激光温喷丸后试样的断口特点。结果表明,经过10 000次循环载荷后,试样表面温度为20、100、200、300及400℃时激光喷丸TC4钛合金试样的残余压应力幅值分别下降至–100、–75、–132、–196与–146 MPa;由于较高的残余压应力幅值及较低的残余应力释放速度,300℃时激光温喷丸试样的疲劳条带间距约为0.42μm,比20℃激光喷丸降低了约64%;300℃时激光温喷丸试样的疲劳寿命高达147 846次,约为20℃激光喷丸试样的1.7倍。
The Nd: YAG nanosecond laser was used to laser shot peening the surface of TC4 titanium alloy dog bone tensile specimens at the surface temperature of 20, 100, 200, 300 and 400 ℃, respectively, and then using the fatigue tester at high Residual stress relief test and fatigue life test were carried out under cyclic fatigue conditions. The thermal field emission scanning electron microscope was used to study the fracture characteristics of the specimens after laser peening. The results show that after 10 000 cycles of loading, the residual compressive stress amplitude of laser shot peening TC4 titanium alloy samples decreases to -100 and -75, respectively, when the sample surface temperature is 20, 100, 200, 300 and 400 ℃. -132, -196 and -146 MPa, respectively. Due to the higher residual compressive stress amplitude and lower residual stress release rate, the fatigue band spacing of laser-shot-peening specimens at 300 ℃ was about 0.42μm, Laser shot peening decreased by about 64%. The fatigue life of laser shot peening specimen at 300 ℃ was as high as 147 846 times, about 1.7 times that of laser shot peening at 20 ℃.