中国激光, 2009, 36 (12): 3323, 网络出版: 2009-12-18   

激光冲击强化对2A02 铝合金疲劳行为的影响

Effect of Laser Shock Strengthening on Fatigue Behaviors of 2A02 Aluminum Alloy
作者单位
1 江苏大学 材料科学与工程学院,江苏 镇江 212013
2 江苏大学 机械工程学院,江苏 镇江 212013
摘要
利用输出波长为1.054 μm,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。
Abstract
The aluminum alloy 2A02 coated with ethyl-silicate black paint was laser shocked using the laser setup with the 1.054 μm output wavelength and the 20 ns short pulse,then the fatigue experiment was carried out. The effect of laser shock processing upon the fatigue behavior of the aluminum 2A02 was analyzed via the comparison of microstructures,hardness and fatigue life of the material before and after the shock. The experiment results indicated that the residual compressive stress of the laser-shocked test material can reach 120 MPa above,and the strengthened depth can reach 1.5 mm,which makes the fatigue life of the material be increased 1.835-2.882 times,comparing to that non-laser-shocked. The scanning electronic microscope (SEM) analysis of the fatigue fracture morphology revealed that the fatigue fracture consists of fatigue crack′s initiation,fatigue crack propagation zone and final rupture,and the fatigue crack initiation on the laser-shocked specimen moves towards the inner layer of laser-hardened surface. The residual compressive stress effectively postpones the initiation of the fatigue cracks,slow-downs the propaganda rate of the cracks,and the cyclic hardening inhabits or reduces the secondary cracks to emerge,therefore the fatigue life of the laser shocked aluminum 2A02 can be remarkably increased.

罗新民, 张静文, 赵广志, 任旭东, 张永康. 激光冲击强化对2A02 铝合金疲劳行为的影响[J]. 中国激光, 2009, 36(12): 3323. Luo Xinmin, Zhang Jingwen, Zhao Guangzhi, Ren Xudong, Zhang Yongkang. Effect of Laser Shock Strengthening on Fatigue Behaviors of 2A02 Aluminum Alloy[J]. Chinese Journal of Lasers, 2009, 36(12): 3323.

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