焊速对水下搅拌摩擦焊接7A04铝合金组织性能的影响

Effect of Welding Speed on Microstructure and Properties of Submerged Friction Stir Welded 7A04 Aluminum Alloy

对7A04-T6铝合金板进行了水下搅拌摩擦焊接(Submerged friction stir welding,SFSW),研究了焊速对焊接接头组织和力学性能的影响。结果表明:采用SFSW成功实现了7A04铝合金的连接,晶粒细化和细小、弥散分布的析出相有效减弱了焊接热软化效应。当旋转速度恒定为950r/min,焊速从95mm/min增大到235mm/min时,接头焊核区的晶粒和析出相随着焊速的增大逐渐细化,抗拉强度系数从84.5%升高到89.0%。不同焊速条件下,拉伸断口均呈现微孔聚合和解理混合断裂特征。

Submerged friction stir welding （SFSW）under water was carried out on the 7A04-T6 aluminum al-loy plates and the effect of welding speed on the microstructure and mechanical properties of the joint was investiga-ted.The results showed that 7A04 aluminum alloy plates were successfully welded by SFSW,and the thermal softe-ning was reduced owing to refined grains and dispersive precipitated phase.With the increase of welding speed from 95 mm/min to 235 mm/min,the size of grains and precipitated phase decreased,and ultimate tensile strength ratio of the joint increased from 84.5% to 89.0% when rotation rate was constant at 950 r/min.All the tensile fracture surfaces presented the characteristic of dimples and cleavage fracture at different welding speeds.