激光喷丸强化对半圆孔件疲劳寿命的影响

为研究激光喷丸强化对7075-T6铝合金半圆孔件疲劳寿命的影响,对激光喷丸与未喷丸的试样进行了对比试验,利用X射线应力仪测定其表面残余应力,并对试样进行疲劳拉伸试验.用扫描电镜观察了两类试样疲劳断口的形貌,并采用数理统计方法对其疲劳寿命进行分析.研究表明:经激光喷丸处理区域,表面存在较大的残余压应力,幅值为310 MPa;未喷丸试样疲劳裂纹条带的宽度为0.7~0.8μm,而喷丸试样疲劳裂纹条带的宽度为0.3~0.4μm,说明喷丸试样裂纹扩展的速度比未喷丸试样慢很多;激光喷丸后半圆孔件的疲劳寿命比未喷丸的疲劳寿命提高了2.8~7.2倍.

Effect of laser shot peening on fatigue life of semicircle hole specimen

In order to investigate the effect of laser shot peening on fatigue life of 7075-T6 Al alloy specimen with a semicircle hole, the comparative tests were conducted between the laser?peened specimen and the un?peened specimen. The surface residual stresses were measured with model X-350A of X?ray diffraction stress analyzer and fatigue tests were carried out. The fatigue fracture morphology of two kinds of specimens were observed with the model JSM-7001F of scanning electron microscope, and the fatigue life was comprehensively studied by statistical analysis. The results show that the laser shot peening can induce the residual compressive stress in laser?peened zone, and its magnitude reaches to 310 MPa. The spacing of the fatigue striations in un?peened specimen is roughly 0.7~0.8μm, while the spacing of the fatigue striations in peened specimen is only 0.3~0.4 μm, which indicates that the crack propagation rate of the peened sample is slower than that of the un?peened case. The average fatigue life of the laser?peened specimen is 2.8~7.2 times than that of the un?peened specimen.