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为了研究6061-T6铝合金激光喷丸后表面残余压应力在循环加载过程中的释放特性,对典型单联狗骨状试样进行激光喷丸处理及保温处理,利用MTS-809拉扭组合材料测试系统进行不同循环应力水平和循环周次的疲劳实验,并使用X-350A型X射线应力测定仪测量试样表面残余压应力的变化。结果表明,残余压应力的松弛主要发生在疲劳过程开始的100次循环周期内,1000次循环周期后残余压应力基本趋于稳定。不同应力水平下的松弛行为表明,循环应力较小时,残余压应力松弛的幅度和速率相对较小;当循环应力接近材料屈服强度时,残余压应力松弛的幅度和速率较大,循环后期残余压应力完全释放,在表面产生残余拉应力。与未经保温处理的激光喷丸试样相比,试样经过150℃保温处理10 min后,表面残余压应力下降,但在循环载荷作用下应力松弛的幅度和速率都较小,残余压应力的稳定性得以提升。
In order to study the release characteristics of surface residual compressive stress after 6060-T6 aluminum alloy laser shot peening in the process of cyclic loading, the typical single-dog bone sample was subjected to laser shot peening and heat preservation treatment. Using MTS-809 tensile and torsion composite material The test system was subjected to fatigue tests with different cyclic stress levels and cycles, and X-350A X-ray stress meter was used to measure the residual compressive stress on the specimen surface. The results show that the residual compressive stress relaxation occurs mainly within 100 cycles at the beginning of the fatigue process, and the residual compressive stress tends to be stable after 1000 cycles. The relaxation behavior at different stress levels shows that the amplitude and rate of residual compressive stress relaxation are relatively small when the cyclic stress is small. When the cyclic stress is close to the yield strength of material, the magnitude and rate of residual compressive stress relaxation are large. The residual pressure The stress is completely released and residual tensile stress is generated on the surface. Compared with the laser shot peening specimens without heat preservation, the residual compressive stress of the specimens decreased after 10 min heat treatment at 150 ℃, but the magnitude and rate of stress relaxation under cyclic loading were small. The residual compressive stress The stability is improved.