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Zn中间层对镁/铝异种金属激光焊接的影响

Effect of Zn interlayer on laser welding of Mg/Al dissimilar metal

  • 摘要: 为了研究激光焊接镁/铝异种金属的工艺方法,采用4kW光纤激光器对AZ31B镁合金和5083铝合金进行了添加Zn中间层的焊接试验,得出了Zn中间层对镁/铝异种金属激光焊接接头的影响机理。结果表明,焊接接头组织较为均匀,热影响区不明显;镁侧熔合区及焊缝中心部位以α-Mg和α-Mg+Mg17Al12共晶组织为主,底部为Al固溶体及Mg/Al,Mg/Zn间化合物组成的混合组织;随着Zn中间层厚度的增加,焊缝底部生成的Mg/Zn化合物数量增多,Mg/Al间化合物数量明显减少,且连续分布的状态得到改善,剪切断裂由解理向混合断裂方式过渡;当中间层厚度为0.1mm时,拉剪强度达到最大值25.47MPa。该研究对提升镁/铝异种金属焊接接头的强度是有帮助的。

     

    Abstract: In order to study the laser welding process of magnesium/aluminum dissimilar metals, the experiment was conducted on AZ31B magnesium alloy and 5083 aluminum alloy with Zn interlayer by using 4kW fiber laser. The influence mechanism of Zn interlayer on Mg/Al dissimilar metal laser welding joint was obtained. The results show that the microstructure of the weld is uniform, and the heat affected zone is not obvious. The magnesium side and the center are mainly composed of α-Mg and α-Mg+Mg17Al12 eutectic structure, and the bottom of weld is the mixture of Al, Mg/Al and Mg/Zn compounds. With the thickness of Zn increased, at the bottom of the weld, the formation of Mg/Zn compounds increase, the Mg/Al compounds reduce and the distribution of microstructure is improved. The shear fracture mode transforms from cleavage to mixed manner. When Zn interlayer is 0.1mm, the shear strength reaches the maximum 25.47MPa. The study is helpful in improving the strength of the Mg/Al dissimilar metal welded joints.

     

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