2219铝合金双主轴回抽式搅拌摩擦焊接头组织与力学性能分析

Microstructure and mechanical properties of 2219 aluminum alloy refilling friction stir welded joints

采用双主轴回抽式搅拌摩擦焊对2219铝合金板进行了焊接,分析了接头的微观组织和力学性能,探讨了搅拌针回抽速度对接头力学性能的影响.结果表明,焊缝平稳段上层试样断裂于前进侧热力影响区,靠近热影响区;平稳段下层试样断裂于焊缝中心的搅拌针端部搅动区;而回抽段焊缝断裂于后退侧热影响区,靠近热力影响区.焊接接头抗拉强度达到母材的70%,断后伸长率为80%以上;当回抽速度为6 mm/min时,断后伸长率最高.硬度最低值位于热力影响区和热影响区交界处.

The 2219 aluminum alloy sheets were welded with refilling friction stir welding technology.The microstructure and mechanical properties of the welded joints were characterized,and the effects of retraction speed of the stir-pin on the mechanical properties of the joints were analyzed.The results show that,for the upper part of the joints obtained in stable welding stage,the fracture during tension test occurred in the thermal-mechanically affected zone(TMAZ) on advancing side;while for the lower part,the specimen fractured in the zone A3.The joints in the retraction part fractured in the heat-affected-zone(HAZ) on retreating side.The tensile strength and elongation of the bead were 70% and 80% of the base metal,respectively.The retraction speed of stir-pin had remarkable effect on the mechanical properties of the joints,and when the retraction speed was 6 mm/min,the elongation of the joints reached the maximum.The lowest microhardness located in the boundary between TMAZ and HAZ.