Improvement of Arc Properties in GTAW of Aluminium Alloys

Abstract

Gas tungsten arc welding (GTAW) is a widely used method of joining aluminium and its alloys. Despite the fact that a lot of research has been done in this area for several decades, there are many unresolved issues on the welding process control. Optimization of square wave alternating current profiles is one of them. This paper presents the results of studies on control of spatial position of an arc by an improved heat input algorithm taking into account the necessary relationship between direct current of straight and reverse polarity. It is shown that an increase in direct current reverse polarity to over 10 A contributes to expansion of a cathode spots space and, consequently, a greater deviation of the arc from the axis of a tungsten electrode. The spatial position of the arc is almost coaxial to the tungsten electrode when direct current reverse polarity is short-term reduced to 5 A at the final stage. These results are correct for a wide range of the square wave alternating current profiles.