HAZ softening behavior of strain-hardened Al-6.7Mg alloy welded by GMAW and pulsed GMAW processes


Gas metal arc welding (GMAW) process was used to weld plates of strain-hardened Al-6.7Mg alloy. It was observed that HAZ softening issue occurred extensively for the current material using the GMAW process. So, as a solution, pulsed current was employed and the plates were welded by pulsed GMAW (PGMAW) process. The effects of peak current (93, 120, 140, and 160 A) and pulse frequency (0.5, 2.0, and 5.0 Hz) on the strength of the weldments were investigated. For high peak currents (160 A), catastrophic defects were formed in the weld metal. It was observed that for the lowest pulse frequency (0.5 Hz), increasing the peak current increased the weld strength. The peak current did not change the strength for higher frequencies (2.0 and 5.0 Hz). Furthermore, increasing the frequency from 0.5 to 2.0 Hz for peak currents of 93 and 120 A led to strength improvement. For peak current of 140 A, frequency changing was ineffective. The overall enhancement in the strength of welds and reduction of HAZ softening by employing pulsed current offers a promising opportunity for further application of GMAW process with controlled heat input for welding of strain-hardened Al-6.7Mg alloy.

Publication Title

International Journal of Advanced Manufacturing Technology