搅拌针形状对6082-T6铝合金静轴肩搅拌摩擦焊接头组织与性能的影响

Effect of The Shapes of Tools on The Structure and Properties of 6082-T6 Aluminum Alloy Welded Joints by Stationary Shoulder Friction Stir Welding

摘要:

采用四种形状的搅拌针对3mm厚的6082-T6铝合金进行静轴肩搅拌摩擦焊焊接，研究了不同形状搅拌针焊接接头的宏观形貌，微观组织，力学性能和断口形貌，以及搅拌针的产热。结果表明三角形搅拌针与四边形搅拌针产热较低，动静体积比较大，接头处塑性金属流动性强，焊接过程中焊缝顶部与底部温差较小，可以形成无缺陷的SSFSW接头；XRD分析表明，焊核区无新的物相产生，三角形搅拌针焊接接头焊核区微晶尺寸最小；各接头的硬度均呈“U”形分布，最低点位于后退侧热机影响区与焊核区交界处，三角形搅拌针接头的硬度整体略高；三角形搅拌针焊接接头的抗拉强度与断后伸长率最高，分别为202.9MPa和3.8%；拉伸断口形貌分析表明，所有接头均为韧性断裂。

Abstract:

Four types of tools were used to weld 3mm 6082-T6 aluminum alloy thought stationary shoulder friction stir welding. The macro morphology, microstructure, mechanical properties and fracture morphology of welded joints by tools of different shapes, as well as the heat generation of the tools were studied. The results show that the triangle tool and the quadrangle tool produce lower heat and have a relatively large dynamic and static volume, which can enhance the flow of plastic metal at the joint, reduce the small temperature difference between the top and bottom of the weld during the welding process, and form a defect-free SSFSW joint. XRD analysis shows that no new phases are generated during the welding process, and the crystallites size of NZ welded by triangle tool is the smallest. The hardness of each joint is distributed in a "U" shape, and the lowest point is at the junction of RS-TMAZ and NZ, but the hardness of the welded joint by triangle tool is slightly higher. The tensile strength and elongation after fracture of the welded joint by triangle tool are the highest, respectively 202.9MPa and 3.8%. Analysis of tensile fracture morphology shows that all joints are ductile fractures.