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对2.2mm厚挤压态AZ71镁合金板材进行交流TIG焊研究,焊接电流分别取70、80和90A。结果表明:电流为90A时,焊缝外观成形良好,无宏观缺陷,焊缝达到熔透状态。用光学显微镜、SEM、EDS等对焊缝的微观组织进行观察分析表明:随着电流的增加,焊缝区和热影响区组织逐渐粗化,热影响区宽度增加。电流的增加还导致焊缝区晶界上β-Mg17Al12相逐渐增多,形态也发生了变化。
AC TIG welding of 2.2mm thick extruded AZ71 magnesium alloy sheet was carried out with welding current of 70, 80 and 90A, respectively. The results showed that the appearance of the weld was well formed with 90A current without macroscopic defects, and the weld reached the penetration state. The observation and analysis of the microstructure of the weld by means of optical microscope, SEM and EDS showed that with the increase of current, the microstructure of the weld zone and the HAZ became coarse and the HAZ width increased. The increase of current also led to the gradual increase of β-Mg17Al12 phase in the grain boundary of the weld zone and the change of morphology.