中文摘要：

采用搅拌摩擦焊接方法对6mm厚的挤压态ZK60镁合金板材进行焊接．在广泛的焊接参数（600-1200r／min的旋转速率和50200mm／min的焊接速度）下，均得到了高质量的焊接接头．在焊接工具的搅拌和摩擦热的联合作用下，在焊核区形成了细小、均匀的再结晶晶粒，同时MgZn2粒子被破碎并大部分固溶入镁基体．对于ZK60镁合金，MgZn2粒子的弥散强化作用高于晶粒细化的作用，因而焊核区的硬度低于母材，拉伸时接头在焊核区发生断裂．在低热输入焊接参数（≤800r／min）下，随焊接参数的变化，焊核区晶粒尺寸、焊接接头的抗拉和屈服强度及延伸率变化较小．在高热输入焊接参数（1200r／min）下，焊核区晶粒明显变大，接头的抗拉和屈服强度略有下降．对焊接接头进行人工时效后，不同热输入条件下得到的焊接接头的强度和延伸率都有明显提高．

英文摘要：

Six millimeters thick ZK60 alloy plates were successfully friction stir welded （FSW）. The sound welded joints were achieved under a wide range of welding parameters （rotation rate of 600-1200 r/min and traverse speed of 5-200 mm/min）. After FSW, the coarse grains in ZK60 alloy were changed to fine equiaxed recrystallized grains at the nugget zone. Furthermore, the coarse MgZn2 particles were broken up and mostly dissolved into the matrix. For the ZK60 magnesium alloy, the precipitation strengthening effect was more dominant than fine-grain strengthening effect. Therefore, hardness value of the nugget zone was lower than those of the parent material and the fracture occurred at the nugget zone. At low heat input parameters （≤800 r/min）, the grain sizes in the nugget zone, and the tensile strengths and elongations of welded joints at different parameters were similar, but at high heat input parameter （1200 r/min）, the grains in the nugget zone became large and the tensile strength of welded joint slightly decreased. After aging treatment, the strengths and elongations of welded joints under different parameters increased and their mechanical properties were similar.