基于应变速率的激光喷丸强化6061-T6铝合金力学性能分析

Analysis on Mechanical Property of 6061-T6 Aluminum Alloy by Laser Shot Peening Based on Strain Rate

为研究不同应变速率下激光喷丸对6061-T6铝合金力学性能的影响,对标准拉伸试样进行单面和双面激光喷丸强化处理,随后在0.0001～0.1s-1 4种连续应变速率加载条件下,对未喷丸、单面喷丸、双面喷丸3组试样进行了力学性能测试,同时测试了试样表面残余应力,分析了喷丸前后材料表面粗糙度变化及其对延伸率的影响,探讨了激光喷丸后力学性能变化的微观机理。结果表明,抗拉强度(UTS)及屈服强度随应变速率的增加而增大,延伸率随应变速率的增加略微减小;与未处理试样相比,单面激光喷丸后,铝合金的抗拉强度及屈服强度得到小幅提高,延伸率大约降低了1%;双面激光喷丸后,铝合金抗拉强度最大提高了10.8%,屈服强度最大提高了12.5%,延伸率降低了2%左右。激光喷丸区域晶粒得到细化,位错密度得以增加,6061-T6铝合金的力学性能得到改善。

In order to investigate the effects of laser shot peening （LSP） on mechanical properties of 6061-T6 aluminum alloy under different strain rates, standard tensile specimens are tested under different conditions like single-side LSP and two-side LSP, followed by the tensile property tests under four different strain rates from 0. 0001 to 0.1 s 1. The distribution of surface residual stress is measured, and surface roughness before and after LSP is observed. Furthermore, the relation between surface roughness and elongation is also investigated. The grain size and microstructure before and after LSP are analyzed. The results show that the ultimate tensile strength （UTS） and yield strength increases but the elongation decreases with the increment of strain rate. Compared with the untreated sample, the UTS and yield strength after single-side LSP increase slightly, and the elongation decreases by about 1%. Mter two-side LSP, the UTS increases by 10.8 %, and the yield strength increases by 12.5 %, the elongation decreases by about 2 %. A large amount of grain is refined and the dislocation density also increases in the laser- peened area, which improves the mechanical properties of 6061-T6 aluminum allov.