Investigations were made of the effects of high-frequency, d-c, straight polarity current pulsations in the range of 2,000-25,000 pulses/s on the quality and mechanical properties of gas tungsten arc (GTA) welds in 2219 aluminum.
Pulsed-current and conventional GTA welds were made on 0.125, 0.250, and 0.350 in 2219 aluminum, using free fall, single-pass butt welds. Results of this investigation show that pulsed-current welds are superior in x-ray integrity to conventional GTA welds made under similar conditions, with discontinuity levels 80% lower for relatively long weldments. High-frequency pulsation is also very effective in avoiding the typical cast structure of weld metal. Such welds exhibit fracture toughness values 10-15% higher than conventional GTA weldments.
Potential manufacturing advantages include higher weld quality (fewer rejects and lower rework costs) and thinner weld lands, which result in lower structural weights.
