Abstract This paper studied the dissimilar aluminum alloys (5082/6061) laser lap welding with different configurations. Two configurations were set up by exchanging the place position of the upper and lower plates under the same parameters. When higher Mg content alloy located as the upper plate, the evaporation of Mg led to the instable welding process and the lower actual heat input, which affected the weld morphology. The solidification microstructures near the fusion line of the two joints were observed by SEM and analyzed by coupling temperature field and phase field method simulation results, longer and wider intergranular liquid channels and more severe solute segregation occurred in 6061/5182 joint. The results validated that 6061/5182 joint had a higher crack sensitivity than 5182/6061 joint. Moreover, crack sensitivity had a greater influence on tensile property than other factors by testing. The two joints presented significantly different porosity and pore morphology. Dense and fine pores appeared when more Mg element content in the upper plate, which related to the failed escape of Mg vapor and the attenuation of laser energy in thickness direction. Moreover, microhardness decreased as Mg element content increasing, because of the dilution effect of the strengthening phases.

中文翻译：

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不同位置配置下5182和6061异种铝合金搭接激光焊接的显微组织、孔隙率和力学性能

摘要 本文研究了不同配置的异种铝合金（5082/6061）激光搭接焊。通过在相同参数下交换上下板的放置位置来设置两种配置。当镁含量较高的合金位于上板时，镁的蒸发导致焊接过程不稳定，实际热输入较低，从而影响焊缝形貌。通过扫描电镜观察两个接头熔合线附近的凝固组织，并结合温度场和相场法模拟结果进行分析，6061/5182接头发生了更长更宽的晶间液体通道和更严重的溶质偏析。结果证实6061/5182接头比5182/6061接头具有更高的裂纹敏感性。而且，通过测试，裂纹敏感性对拉伸性能的影响大于其他因素。两个节理呈现出明显不同的孔隙率和孔隙形态。上板中Mg元素含量较多时出现致密细孔，这与Mg蒸气逸出失败和激光能量在厚度方向衰减有关。此外，由于强化相的稀释作用，显微硬度随着 Mg 元素含量的增加而降低。