超声对不同铝合金搅拌摩擦焊接头性能的影响

利用自行研制的超声搅拌摩擦焊机分别对2219,7A52,LF21铝合金进行了常规搅拌摩擦焊和超声搅拌摩擦焊两种不同焊接的试验,并对常规搅拌摩擦焊与超声搅拌摩擦焊焊缝的微观组织、拉伸断口形貌进行了对比分析.结果表明,超声搅拌摩擦焊与常规搅拌摩擦焊相比热影响区几乎消失;超声搅拌摩擦焊焊缝焊核区组织比常规搅拌摩擦焊焊核区组织晶粒更加细小;断口扫描电镜图显示母材断口韧窝具有非等轴状待征,韧窝边上撕裂棱明显表明为韧性断裂;超声搅拌摩擦焊断口韧窝撕裂棱不明显;超声搅拌摩擦焊比常规搅拌摩擦焊的平均抗拉强度有所提高,但断后伸长率有所降低.

Effects of ultrasonic on properties of joints welded by friction stir welding process

In this paper,joints of 2219,7A52 and LF21 aluminum alloy were obtained by using a self-made ultrasonic friction stir welding machine.The microstructures and fractography of these joints were studied.The results show that the thermal mechanically affected zone(TMAZ) of ultrasonic friction stir welding is almost disappearing;The grains of weld nugget zone(WNZ) by ultrasonic friction stir welding are much finer than the ones obtained by conventional friction stir welding;The tensile fracture of base material appears to be mixed fracture with dimple and tear ridges.The tensile fracture of ultrasonic friction stir welding appears to be a dimple pattern.Although the tensile strength of joints obtained by ultrasonic friction stir welding are higher than the ones obtained by conventional friction stir welding,the elongation of the joints fellow on opposite tendency.