Abstract
Preheating of welding wire by electric current is an established technique for increasing deposition rate during welding, but is a relatively new contribution to additive manufacturing. The few studies that have been performed for additive methods have focused on a limited selection of materials, typically only one material grade, which limits their relevance to other material grades. This study has investigated the effect of resistive wire preheating, also known as hotwire, in a coaxial directed energy deposition system with laser beam and wire (DED-LB/wire), across a wider range of material grades so that effects of hotwire on different alloy compositions and crystal lattice structures can be determined. Inconel 625, aluminium bronze, nickel-aluminium bronze, carbon steel, austenitic, martensitic and duplex stainless steels were examined to provide a sampling of Ni-, Cu- and Fe-based alloys, as well as a comparison of austenitic, martensitic and duplex stainless steels.