工艺参数和搅拌头尺寸对2024铝合金和AZ31镁合金异种金属搅拌摩擦连接接头性能的影响∗

摘要

Defect-free butt joints of 2024 Al alloy to AZ31 Mg alloy plates with 3 mm thickness were performed using friction stir joining (FSJ).The joining was carried out at five different parameters and using two kinds of geo-metric shape tools.Effects of joining parameter on microstructures,tensile strength and hardness distributions of the joints were investigated.The dissimilar joint presents an even microhardness distribution and obvious material bounda-ry with a rotation speed of 500 r/min and joining speed of 500 mm/min and using a tool with 15 mm diameter shoul-der,existence of mechanical lock and no intermetallic compounds was found.At rotation speed of 300 r/min and joi-nting speed of 30 mm/min,the fracture position is located at the boundary of materials mixed area and TMAZ on Al alloy side,the joint presents approximate tensile strength compared to the former due to dissimilar materials mixing al-though massive intermetallic compounds exist.%研究了2024铝合金与 AZ31镁合金的异种搅拌摩擦连接工艺，并获得了良好的3 mm 板材对接接头。采用5种不同的工艺参数和两种不同尺寸的搅拌头进行加工。研究了不同工艺参数对接头微观组织、拉伸强度和硬度分布的影响。结果表明，使用15 mm轴肩的搅拌头能够获得无缺陷的接头，在转速500 r/min、连接速度500 mm/min的工艺参数下，显微硬度分布均匀，材料边界明显，异种材料间的机械锁和结构增大了接头强度。在转速300 r/min、连接速度30 mm/min的工艺参数下，拉伸断裂位置位于铝合金一侧的热机影响区和材料混合区的交界处，虽然接头存在金属间化合物，但充分的材料混合使接头拉伸强度与前者相当。