Current mode effects on weld bead geometry and heat affected zone in pulsed wire arc additive manufacturing of Ti-6-4 and Inconel 718

Abstract

For the last decade, additive manufacturing (AM) has been revolutionising the aerospace industry, building and repairing various components for aircrafts and outer space vehicles. Despite the fact that AM is gaining rapid adoption by the industry, it is still considered a developing technology, with ongoing research in a variety of fields. Wire arc additive manufacturing (WAAM), a welding-based AM technology, is an active field of research as well, because it enables economical production of large-scale metal components with relatively high deposition rates. In this article, the effects on the weld-bead geometry and heat affected zone from high and low frequency pulsed current are explored on Gas Tungsten Arc Welding (GTAW). The materials used in this investigation were selected to be Ti-6-4 and Inconel 718, both highly used in the aerospace industry for their high strength-to-weight ratio and strength at elevated temperatures respectively. The design of the experiments followed a Taguchi-inspired orthogonal array, altering, apart from the current modes and values, the torch travel speed driven by an industrial robotic arm as well as the wire-feeding rate. The results demonstrate the ability to control both the weld-bead dimensions and penetration depth, as well as the heat affected regions, by utilizing the dual pulsing combination of both high and low frequency pulsing. Alterations from wide beads with deep penetration to narrower beads with greater height-to-width ratios are demonstrated in a single manufacturing setup, enabling further development of the WAAM process.