激光冲击处理对2195铝锂合金蠕变时效行为及回弹的影响

Effect of Laser Shock Peening on Creep Aging Behavior and Springback of 2195 Al-Li Alloy

摘要:

采用硬度测试、微观组织表征和蠕变时效成形实验研究了激光冲击处理对2195铝锂合金蠕变时效行为的影响，并探讨了激光冲击处理对蠕变时效成形单曲率构件回弹的影响。结果表明，相比于未经激光冲击处理的蠕变时效合金，经激光冲击处理后的蠕变时效合金硬度值提升约22%，且晶粒尺寸从板材表层到中间层显著降低，其中表层晶粒尺寸在2种工艺处理后的差异最大（49 μm），中间层晶粒尺寸的差异最小（4 μm）；经激光冲击处理的蠕变时效合金内部的T1析出相分布更密集，数量更多，尺寸更细小。此外，经激光冲击处理的蠕变时效成形板材，与未经过处理的板材相比，其回弹率明显下降，降低幅度约37.6%。硬度提升归因于激光冲击带来的细晶强化和显著的析出强化，回弹率的降低是由于激光冲击处理后的板材凹面在弯曲过程中受到的压应力与激光冲击产生的残余压应力共同作用而产生了更大的蠕变变形。

Abstract:

Hardness testing, microstructural characterization, and creep aging forming experiments were conducted to investigate the impact of laser shock peening (LSP) treatment on the creep aging behavior of 2195 Al-Li alloy and to evaluate its effect on the springback of single-curved components formed through creep aging. The results indicate that, compared to the creep-aged alloy without LSP treatment, the hardness of the creep-aged alloy with LSP treatment is increased by approximately 22%. Grain size is notably reduced from the surface to the middle layer of the plate, with the greatest decrement in surface layer (49 μm) and the least in the middle layer (4 μm). The T1 precipitate phase in the creep-aged alloy with LSP treatment exhibits a denser distribution, greater quantity, and finer grain size, compared with that without LSP treatment. Furthermore, the springback ratio of creep-aged sheets subjected to LSP treatment is significantly lower than that of untreated sheets, decreasing by about 37.6%. The enhancement in hardness is attributed to fine grain strengthening and substantial precipitation strengthening induced by LSP. The reduction in springback is ascribed to the increased creep deformation resulting from the combined effect of the compressive stress on the concave surface of the plate during bending and the residual compressive stress generated by LSP treatment.