中文摘要：

以AZ31B镁合金为研究对象，采用TIG焊接方法，研究了外加纵向磁场对镁合金焊缝成形、焊缝组织及其焊接裂纹的影响规律。研究表明：在外加脉冲交变纵向磁场作用下，镁合金焊缝的熔宽增大，熔深减小，焊缝晶粒细化，析出相增加并呈弥散化分布状况；外加磁场影响了镁合金的焊缝成形和显微硬度，能够控制镁合金焊缝组织、减少镁合金焊缝热裂纹的产生，改善镁合金焊缝的性能。

英文摘要：

With AZ31B magnesium alloy as representative, the effect of pulse longitudinal magnetic field on weldment formation, microstructure and cracks of magnesium alloy was studied by TIG welding and spot welding. Results show that with the effect of the additional pulse longitudinal magnetic field, the width increases of the alloy weldment, the depth reduces, grains are refined and the precipitates increases and distributes dispersively. It influences the weldment formation of magnesium alloy. The magnetic field can also control the weldment microstructure, decrease the cracks and improve the welding quality of the magnesium alloy.