超声冲击对Al-Cu合金TIG焊缝微观组织演变的影响

Effect of ultrasonic impact on Al-Cu alloy TIG weld microstructure evolution

随焊超声冲击焊接通过控制超声冲击工具头的上下运动,实现对焊缝的随焊冲击处理,同时向熔池中导入周期性超声能量.熔池内金属流动状态周期性变化,使得焊缝表面形成明显的类似鱼鳞纹状结构.对比随焊超声冲击焊接和普通TIG焊Al-Cu合金熔池结晶情况.结果表明,周期性超声能量的导入使熔池结晶呈现周期性.有超声作用时,焊缝晶粒细化、细长共晶组织被打碎,焊缝中细晶区宽度与焊接速度、单个周期内超声作用时间线性相关.当超声开始导入时,形成带状组织结构,组织内部θ相细小且分布均匀;超声撤离时,共晶组织呈线状析出,有聚集趋势.

Trailing ultrasonic impact welding( TUIW),impacted the welds by controlling the impact-tool up and down,with periodic ultrasonic energy conducted to the molten pool at the same time. Metal flowing patterns changed periodically under the influence of periodic ultrasonic energy,obvious scales formed in the welds surface similar to the fish-scale. Compared with conventional TIG,it turns out that TUIW periodic ultrasonic energy leads to periodic crystallization during Al-Cu alloy molten pool solidification process. With ultrasonic in,the weld grains were refined and the elongated eutectics were broken down,the width of small grain zone depend linearly on welding velocity and the ultrasonic action time in a single cycle. When ultrasonic began to import,banded structure formed in the weld,θ phase was small and distributed evenly within the organization. Meanwhile,eutectic organization precipitated linearly and tended to be gathered.