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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。
The underwater friction stir welding (SFSW) technology was used to connect the 2024-T4 aluminum alloy plates. The microstructure and mechanical properties of the welded joints were studied. The results show that the grain size can be remarkably refined by SFSW, and the average grain size of the nugget nucleus reaches 700 nm. However, the precipitation phase of the nugget nucleus obviously coarsens. Tensile strength of the welded joint is 86.9% of the tensile strength of the base metal, and the junction of the nugget zone and the thermo-mechanical affected zone becomes the weakened zone. Precipitation strengthening plays a major role in the joint performance, fine grain strengthening is weak.