焊接参数对AZ31镁合金搅拌摩擦焊接头组织和力学性能的影响
Influence of Welding Parameters on Microstructure and Mechanical Properties of Welded Joints of AZ31 Alloy by Friction Stir Weld
熊 峰， 张大童， 鄢 勇， 邱 诚
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作者单位：（华南理工大学 机械与汽车工程学院，广东 广州 510640）
中文关键字：搅拌摩擦焊； AZ31镁合金； 微观组织； 力学性能
英文关键字：friction stir weld; AZ31 alloy; microstructure; mechanical properties
中文摘要：研究了板厚为6 mm的AZ31镁合金搅拌摩擦焊工艺，并对接头的断裂机制进行了考查。在转速为1000 r/min，焊接速度为60 ～ 300 mm/min条件下获得表面平整，无缺陷的焊缝。与母材相比，搅拌区的晶粒得到明显细化。随焊接速度增加，搅拌区的晶粒尺寸减小。搅拌区的硬度高于其他区域。焊接速度为150 mm/min时，接头拉伸强度最高，达到母材的92.7%。断裂多发生在热影响区，热影响区晶粒粗大且分布不均，显微硬度最低，是焊接接头的薄弱环节。
英文摘要：AZ31 alloy plate with 6 mm thickness was welded by friction stir, and the tensile fracture mechanism of FSW joints was investigated. At a constant rotation rate of 1000 r/min, the defect-free joints could be obtained under the welding speed 60 ～ 300 mm/min. Coarse grains in base material change into fine equiaxed grains in stir zone after FSW. The size of grain in stir zone decreases with the welding speed increasing. The microhardness shows that the hardness of stir zone is higher than that of other zones. The joints with the tensile strength of 92.7% of the base material was achieved at the welding speed of 150 mm/min. The heat affected zone (HAZ) is the weakest zone in the whole weld due to the inhomogeneous distribution of coarse grains and the lowest hardness is in the HAZ.