Ti-6Al-4V超高频脉冲GTAW焊缝气孔分析

Study on weld porosity in Ti-6Al-4V titanium alloy with ultra high frequency pulsed GTAW

以Ti-6Al-4V钛合金为母材金属进行焊缝气孔研究,试验发现与常规电弧焊接(conventional GTAW,CGTAW)相比,超高频脉冲GTAW(ultra high frequency pulsed GTAW,UHFP-GTAW)具有较好的焊缝气孔清理效果,可有效减少甚至清除气孔缺陷.结合UHFP-GTAW电弧行为对焊缝气孔形成的气泡长大、脱离熔池壁面、上浮逸出等三个阶段分别进行分析.结果表明,在高频脉冲电弧作用下,气泡受压,有利于气泡核长大;表面张力变大,有利于附着气泡脱离熔池壁面;Ti-6Al-4V钛合金熔池粘度随温度升高而减小,气泡逸出速度随之增大,有利于降低焊缝气孔敏感性.

The study on weld porosity was carried out with Ti-6Al-4V titanium alloy. The experimental data indicated that the significant porosity elimination can be found with ultra high frequency pulsed GTAW( UHFP-GTAW),no porosity or much less porosities in weld compared with conventional GTAW( CGTAW). The research focused on influence of arc behavior of UHFP-GTAW to porosity during growth period,detaching period,and escape period respectively. The results showed the benefits for the growing of gas pores nucleus which are pressed,the detaching process of the gas pore with higher surface tension,and decreasing of sensibility of weld porosity when the temperature in the molten pool increased which made less viscosity of the liquid metal and a large escape velocity on the condition of UHFP-GTAW.