(湖南大学 材料科学与工程学院，长沙 410082)
摘 要: 采用CO2激光对轧制态ZK40镁合金板材进行焊接，并研究焊接工艺参数对接头显微组织及力学性能的影响规律。结果表明：在合理的工艺条件下，可以获得成型良好的焊接接头，其抗拉强度可达到315MPa，为母材的91.3%；熔池边界无外延生长的柱状晶，整个熔池完全由细小均匀的等轴树枝晶组成；分布于晶界及枝晶臂间的第二相粒子主要是Mg51Zn20；随着焊接热输入的增大，枝晶臂生长更为发达，晶粒粗化。
关键字: ZK40镁合金；激光焊接；显微组织；力学性能
（School of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The as-rolled ZK40 magnesium alloy sheets were joined by laser beam welding. The effects of welding parameters on the microstructures and mechanical properties of the joints were studied. The results show that a sound bead, with the ultimate tensile strength of 315 MPa, up to 91.3% of that of base metal, can be obtained with the optimized welding parameters. No columnar grains can be found at the fusion boundary, and the fusion zone (FZ) is characteristic of equiaxed dendritic grains and fine Mg51Zn20 precipitates disperse along the grain boundaries and among the dendritic arms. With the heat input increasing, the grains in FZ get coarser and more dendritic.
Key words: ZK40 magnesium alloy; laser beam welding; microstructure; mechanical property
