水下搅拌摩擦焊接铝合金组织与性能研究

Study on Microstructure and Properties of Aluminium Alloy Submerged Friction Stir Welding

采用水下搅拌摩擦焊接(SFSW)技术对2024-T4铝合金板材进行连接,研究了焊接接头的微观组织和力学性能。结果表明:SFSW可以显著细化晶粒,焊核区的平均晶粒尺寸达到700nm,但焊核区的析出相明显粗化。焊接接头的抗拉强度为母材抗拉强度的86.9%,焊核区和热机械影响区交界处成为接头的薄弱区。沉淀强化对接头性能起到主要作用,细晶强化作用较弱。

2024-T4 aluminium alloy plate was jointed by submerged friction stir welding（SFSW）,and the microstructures as well as mechanical properties of the weld were measured experimentally.The results show that SFSW causes significant grain refinement with an average grain size of 700 nm but coarsens precipitates in the nugget zone.The ultimate tensile strength of the weld is 86.9 percent of the base metal.The interface between the nugget zone and the thermo-mechanically affected zone is the weak zone of the SFSW joint.Precipitation strengthing is the main strengthing mechanism while the grain refinement strengthing is relatively weak.