Assessing the effect of TIG alternating current time cycle on aluminium wire plus arc additive manufacture

The effect of electrode positive time cycle (% EP) of the alternating current TIG process has been investigated for aluminium wire + arc additive manufacture of linear walls. The study considered the effect on oxide removal, linear wall dimensions, microstructure, mechanical properties as well as the effect on electrode wear. The results showed that the effective wall width was minimum at 20%EP with a corresponding maximum in layer height. It was also observed that increasing the% EP increased the electrode wear rate, which in turn affected the arc stability. Microstructure analysis showed a noticeable increase in the grain size for higher% EP. The study also showed that% EP had no significant effect on mechanical properties. From a heat input analysis, a direct correlation was observed between the arc voltage and the% EP. The study also indicated that there could be other contributing factors to wall dimensions. For aluminium wire + arc additive manufacture of linear walls, minimum cleaning ranged between 10%EP and 20%EP. (C) 2017 Elsevier B.V. All rights reserved.