AZ31镁合金激光自熔焊工艺及接头的性能

Laser Welding Process of AZ31 Magnesium Alloy and Performance of Joint

采用对接激光自熔焊方法焊接4 mm厚的AZ31镁合金,通过微观组织分析和力学性能测试研究了激光自熔焊工艺参数对镁合金激光焊接头焊缝成形、组织以及力学性能的影响。试验结果表明:采用试验范围内的工艺参数,可以获得焊缝成形良好、无明显焊接缺陷的接头。焊接速度从3 m/min增大到3.9 m/min,焊缝尺寸和接头抗拉强度变化较小。随着激光功率从2.4 kW增加到3.0 kW,接头抗拉强度逐渐减小。焊缝组织为晶粒均匀分布的等轴晶,其晶粒呈六角形,焊缝区硬度明显低于母材。当激光功率为2.4 kW、焊接速度为3 m/min时接头抗拉强度最高,为193 MPa。

4 mm thick AZ31 magnesium alloy was connected by using butt laser welding. The effects of laser welding process parameters on the weld formation, microstructure and mechanical properties of magnesium alloy laser welded joints were investigated by means of microstructure analysis and mechanical properties testing. The experimental results show that,it is possible to obtain joints with good weld formation and without obvious weld defects by using the welding process parameters within the test range. As the welding speed increases from 3 m/min to 3.9 m/min, the change of weld size and tensile strength of joint are not obvious. As the laser power increases from 2.4 kW to 3.0 kW, the tensile strength of the joint decreases gradually. The weld microstructure is uniformly distributed equiaxed crystal whose grain shape is hexagonal. The hardness of weld area is significantly lower than that of the base metal. The maximum tensile strength of the joint is 193 MPa when the laser power is 2.4 kW and the welding speed is 3 m/min.