Various methods have been proposed to modify the friction stir welding. Friction stir vibration welding and underwater friction stir welding are two variants of this technique. In friction stir vibration welding, the adjoining workpieces are vibrated normal to the joint line while friction stir welding is carried out, while in underwater friction stir welding the friction stir welding process is performed underwater. The effects of these modified versions of friction stir welding on the microstructure and mechanical characteristics of AA6061-T6 aluminum alloy welded joints are analyzed and compared with the joints fabricated by conventional friction stir welding. The results indicate that grain size decreases from about 57 μm for friction stir welding to around 34 μm for friction stir vibration welding and about 23 μm for underwater friction stir welding. The results also confirm the evolution of Mg₂Si precipitates during all processes. Friction stir vibration welding and underwater friction stir welding processes can effectively decrease the size and interparticle distance of precipitates. The strength and ductility of underwater friction stir welding and friction stir vibration welding processed samples are higher than those of the friction stir welding processed sample, and the highest strength and ductility are obtained for underwater friction stir welding processed samples. The underwater friction stir welding and friction stir vibration welding processed samples exhibit about 25% and 10% higher tensile strength compared to the friction stir welding processed sample, respectively. The results also indicate that higher compressive residual stresses are developed as underwater friction stir welding and friction stir vibration welding are applied.

已经提出了多种方法来改进摩擦搅拌焊接。搅拌摩擦振动焊接和水下搅拌摩擦焊接是该技术的两种变体。在搅拌摩擦振动焊接中，相邻工件在进行搅拌摩擦焊接时垂直于接缝线振动，而在水下摩擦搅拌焊接中，摩擦搅拌焊接过程在水下进行。分析了这些改进版本的搅拌摩擦焊对 AA6061-T6 铝合金焊接接头的微观结构和力学特性的影响，并与传统搅拌摩擦焊制造的接头进行了比较。结果表明，晶粒尺寸从搅拌摩擦焊的约 57 μm 减小到搅拌摩擦振动焊的约 34 μm 和水下搅拌摩擦焊的约 23 μm。结果也证实了 Mg₂Si在所有过程中沉淀。搅拌摩擦振动焊接和水下搅拌摩擦焊接工艺可以有效降低沉淀物的尺寸和颗粒间距离。水下搅拌摩擦焊和搅拌摩擦振动焊接加工样品的强度和延展性高于搅拌摩擦焊接加工样品，水下搅拌摩擦焊接加工样品获得最高的强度和延展性。与搅拌摩擦焊接处理的样品相比，水下搅拌摩擦焊接和搅拌摩擦振动焊接处理的样品分别表现出高约 25% 和 10% 的拉伸强度。