Gas Metal arc Pulse Welding with Alternating Current for Lightweight Materials

Abstract

So-called heat-reduced arc welding processes dominate the joining technology in the automotive sector today. They offer the advantage to reduce deformation of thin walled plates. Also, metallurgy and material properties are affected decisively. Based on the present state of the art in power-controlled gas metal arc welding (GMAW) this paper present the developing of a welding process, that allows a quasi-decoupling of the energy input between filler metal and base material. This is being realized by a polarity reversal. In conjunction with pulse control and the specific adjustment of the pulse a significant improvement of the arc stability can be achieved. This applies particularly to non-ferrous materials tending to concentrate oxygen on its surface like aluminum, magnesium and their combinations, respectively. Especially it is possible to control the deposition rate, welding formation and bonding conditions between base material and filler metal. Furthermore spatter can be reduced and manufacturing time can be saved. The present investigation includes the comparison between various modern GMAW processes, such as ColdMIG®, CMT® and short arc, with the pulsed GMAW using alternating current (AC) for welding aluminum. Thereby, mainly the penetration depending on the heat input is taken into account. It can be noted that the AC pulsed GMAW process produces weld seams of the same quality as well-known processes in matters of height and width of the joint. The generated welds have low notches at the edge of the seam and a uniform weld scaling. Visual imperfections on the surface have not been detected.