Weld appearance of 2219-T87 high strength aluminum alloy at different pulse frequency

Based on hybrid ultrahigh frequency pulse variable polarity gas tungsten arc welding process of 2219-T87 high strength aluminum alloy, the effect of pulse frequency on weld appearance was analyzed. Experimental results show that the pulse frequency has a great impact on arc characteristics and the molten pool flow behavior, which makes significant changes in the weld width, depth and penetration. When the pulse frequency f_H is less than 60 kHz, the weld width and depth increase with the increase of pulse frequency. The weld penetration is hardly changed with f_H<35 kHz, while it is considerably improved by at least 34% compared with the conventional variable polarity GTAW process when f_H>35 kHz. When the pulse frequency reached up to 60 kHz, the weld penetration significantly increases by 60% compared with the conventional variable polarity GTAW process. When the pulse frequency f_H>65 kHz, the weld width, depth and penetration presented show the downward trend.