论文部分内容阅读
利用输出波长为1.054μm,脉冲宽度为20 ns的激光,对表面涂覆硅酸乙酯吸收涂层的2A02铝合金进行了冲击强化和疲劳试验。通过对冲击处理前后材料的微观组织、硬度和疲劳寿命的比较,分析了激光冲击处理对2A02铝合金材料疲劳行为的影响。结果表明,激光冲击强化可使2A02铝合金表面残余压应力达到120 MPa以上,强化层深度达1.5 mm,疲劳寿命为未经激光冲击强化处理试样的1.835~2.882倍。对合金疲劳试样断口微观形貌的扫描电镜(SEM)分析结果表明,疲劳断口由疲劳源、疲劳区和瞬断区组成,经激光冲击强化的试样疲劳源移向激光强化层以内,残余压应力有效地延迟疲劳源区的裂纹萌生,减缓疲劳裂纹的扩展速率,“循环硬化”有效抑制或减少了二次裂纹的产生,使激光冲击2A02铝合金的疲劳寿命得以大幅提高。
The impact strength and fatigue tests were carried out on 2A02 aluminum alloy coated with ethyl silicate absorption coating by laser with output wavelength of 1.054μm and pulse width of 20 ns. By comparing the microstructure, hardness and fatigue life of the material before and after impact treatment, the impact of laser impact treatment on the fatigue behavior of 2A02 aluminum alloy was analyzed. The results show that laser shock can make the residual compressive stress of 2A02 aluminum alloy reach 120 MPa and the depth of strengthening layer reaches 1.5 mm. The fatigue life is 1.835 ~ 2.882 times higher than that without laser shock. The SEM micrographs of the fatigue fracture surface of the alloy showed that the fatigue fracture was composed of the fatigue source, the fatigue zone and the instantaneous fracture zone. The fatigue source of the specimen strengthened by the laser shock moved to the inside of the laser strengthened layer, and the residual The compressive stress effectively delayed the crack initiation in the fatigue source zone and slowed down the expansion rate of the fatigue crack. The “cycle hardening” effectively suppressed or reduced the occurrence of secondary cracks, and greatly improved the fatigue life of the laser shock 2A02 aluminum alloy.