AZ31B magnesium alloy sheets of 4.0 mm in thickness were successfully butt-welded by using laser beam welding (LBW). The effects of laser beam welding parameters such as laser power, welding speed and focal position on microstructure revolution and mechanical properties of AZ31B magnesium alloy were investigated. The results showed that the welded joints fabricated using a laser power of 2.5 kW, welding speed of 30 mm/s and focal position of + 2 mm presented optimized macroscopic morphology and best tensile properties compared with the other joints. The formation of fine grains in weld zone and uniformly distributed fine precipitates were the main reasons for superior tensile properties of these joints. In addition, there was only α-Mg phase and no β-Mg₁₇Al₁₂ was observed in the weld zone. The spherical particles in the weld zone were α-Mg segregation rich in Al and Mn.

采用激光束焊接 (LBW) 成功地对焊了 4.0 mm 厚的 AZ31B 镁合金板。研究了激光功率、焊接速度、焦点位置等激光束焊接参数对AZ31B镁合金组织转数和力学性能的影响。结果表明，激光功率为2.5 kW、焊接速度为30 mm/s、焦点位置为±2 mm的焊接接头与其他接头相比具有优化的宏观形貌和最佳的拉伸性能。焊缝区细晶粒的形成和均匀分布的细析出物是这些接头具有优异拉伸性能的主要原因。此外，只有α-Mg相，没有β-Mg ₁₇ Al ₁₂在焊接区观察到。焊缝区球状颗粒为富含Al和Mn的α-Mg偏析。