Abstract

A longitudinally varying magnetic field (MF) was applied during cold metal transfer (CMT) welding of Al alloys. The effect of MF on the welding process, macrostructure, microstructure and properties of weld beads was studied. The results showed that the application of MF led to arc expansion and rotation, the droplet transfer frequency decreased, the droplet volume became larger, and the droplets deflected. When the coil current was between 0 and 5 A, the weld beads porosity decreased from 4.47 to 0.26%. And when the coil current was increased to 8 A, the porosity of weld beads also increased to 2.84%. MF reduced the weld depth, wetting angle and weld reinforcement, and increased weld width. With the increase of coil current, the width of primary dendrite arms decreased from 7.75 to 5.01 μm. The area occupied by the Al–Si eutectic was enlarged, and the eutectic was refined. It was also found that the MF slightly increased the hardness of the weld beads, and the hardness distribution was more uniform.

Graphic Abstract

中文翻译：

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纵向磁场对铝合金CMT焊接的影响

摘要

在铝合金的冷金属转移（CMT）焊接过程中施加了纵向变化的磁场（MF）。研究了MF对焊接工艺，焊道宏观组织，微观组织和性能的影响。结果表明，MF的应用导致电弧的膨胀和旋转，液滴的传递频率降低，液滴的体积变大，液滴发生偏转。当线圈电流在0至5 A之间时，焊缝孔隙率从4.47降低至0.26％。并且当线圈电流增加到8 A时，焊道的孔隙率也增加到2.84％。MF减少了焊接深度，润湿角和焊接增强，并增加了焊接宽度。随着线圈电流的增加，初级枝晶臂的宽度从7.75减小至5.01μm。Al-Si共晶所占面积扩大了，共晶被提炼。还发现MF稍微增加了焊道的硬度，并且硬度分布更均匀。

图形摘要