中文摘要：

采用激光焊接技术成功焊接了2．0mm厚ZK60变形镁合金板材并研究了焊接参数（激光功率和焊接速度）对接头组织和力学性能的影响。在优化工艺参数下，可以获得良好的焊接接头，其抗拉强度为300MPa，伸长率为12．0％，分别高达母材的92．5％和65％。轧制板材晶粒细小且存在很多微细的析出相，对液化开裂具有抑制作用，从而没有观察到半熔化区（PMZ）的液化开裂现象。熔化区（FZ）具有等轴晶特征，平均晶粒粒径为8μm，与热影响区（HAZ）组织特征相似。这种组织特征有助于获得较高的焊接效率。

英文摘要：

Fine-grained ZK60 magnesium alloy sheets of 2.0 mm in thickness were successfully joined by laser beam welding （LBW）. The effects of welding parameters including laser power and welding speed on the microstructures and mechanical properties of the joints were investigated. A sound bead, with the ultimate tensile strength （UTS） of 300 MPa and elongation of 12.0%, up to 92.5% and 65% of those of the base metal, respectively, is obtained with the optimized welding parameters. No liquation cracking is visible in the partially melted zone （PMZ） owing to the inhibitory action of the fine dispersed precipitates and the fine-grained microstructure in the as-rolled magnesium alloy sheets. The fusion zone （FZ） is featured with the equiaxed dendritic grains of the average grain size about 8 μm, which are similar to those in the heat affected zone （HAZ）, and this contributes to the relatively high joint efficiency.