目的 针对高强7A52铝合金在MIG焊接过程中易出现组织不均匀及接头性能下降的问题,系统探讨电弧摆动频率与焊后T6热处理对焊接接头组织演化及力学性能的调控作用,阐明二者的协同强化机制。方法 以7A52铝合金为研究对象,开展不同摆动频率条件下的坡口修复MIG焊接试验,并对焊接接头实施T6焊后热处理。同时通过微观组织分析、EDS能谱分析、显微硬度测试及拉伸性能测试对接头性能进行表征。结果 摆动频率的变化显著影响熔池流动行为,随着摆动频率的提高,焊缝组织由柱状晶向等轴晶转变,晶粒明显细化。经T6热处理后,焊缝区强化元素重新分配,析出相数量增多且分布更加均匀,焊接接头综合力学性能显著提升。在摆动频率为3 Hz并结合T6热处理条件下,焊接接头性能达到最优,其平均显微硬度为166HV,最高显微硬度达180.33HV,最大抗拉强度为472.28 MPa。结论 摆动频率与焊后热处理之间存在明显的协同强化效应,为7A52铝合金高性能MIG焊接接头的工艺优化提供了理论依据。
Abstract
To address the issues of microstructural inhomogeneity and degradation of joint performance in high-strength 7A52 aluminum alloy during MIG welding, the work aims to systematically investigate the effects of torch oscillation frequency and post-weld T6 heat treatment on the microstructural evolution and mechanical properties of welded joints, thereby elucidating their synergistic strengthening mechanism. MIG welding experiments with groove repair were conducted under different oscillation frequencies with 7A52 aluminum alloy, followed by T6 post-weld heat treatment. The joint performance was characterized by optical microscopy, energy-dispersive spectroscopy (EDS), microhardness testing, and tensile testing. The results indicated that oscillation frequency had a significant effect on molten pool flow behavior. With the increasing oscillation frequency, the weld microstructure transformed from columnar grains to equiaxed grains, with significant grain refinement. After T6 heat treatment, strengthening elements in the weld zone were redistributed, leading to an increased number of precipitates with a more uniform distribution, thereby significantly improving the overall mechanical properties of the welded joints. Under the combined condition of an oscillation frequency of 3 Hz and T6 heat treatment, the welded joint exhibited optimal performance, with an average microhardness of 166HV, a peak microhardness of 180.33HV, and a maximum tensile strength of 472.28 MPa. The results demonstrate a pronounced synergistic strengthening effect between oscillation frequency and post-weld heat treatment, providing a theoretical basis for optimizing the welding process of high-performance MIG welded joints of 7A52 aluminum alloy.
关键词
摆动频率 /
7A52铝合金 /
热处理 /
显微组织 /
力学性能
Key words
oscillation frequency /
7A52 aluminum alloy /
heat treatment /
microstructure /
mechanical properties
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基金
北京市教育委员会科研计划（KM202310017006）; 国家自然科学基金联合基金重点支持项目（U22B20127）
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