Robust interface and excellent as-built mechanical properties of Ti–6Al–4V fabricated through laser-aided additive manufacturing with powder and wire

Abstract

The feasibility of manufacturing Ti–6Al–4V samples through a combination of laser-aided additive manufacturing with powder (LAAM_p) and wire (LAAM_w) was explored. A process study was first conducted to successfully circumvent defects in Ti–6Al–4V deposits for LAAM_p and LAAM_w, respectively. With the optimized process parameters, robust interfaces were achieved between powder/wire deposits and the forged substrate, as well as between powder and wire deposits. Microstructure characterization results revealed the epitaxial prior β grains in the deposited Ti–6Al–4V, wherein the powder deposit was dominated by a finer α′ microstructure and the wire deposit was characterized by lamellar α phases. The mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and discussed. The mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications (AMS 6932) even without post heat treatment. No fracture occurred within the interfacial area, further suggesting the robust interface. The findings of this study highlighted the feasibility of combining LAAM_p and LAAM_w in the direct manufacturing of Ti–6Al–4V parts in accordance with the required dimensional resolution and deposition rate, together with sound strength and ductility balance in the as-built condition.

Keywords

laser-aided additive manufacturing / powder deposition / wire deposition / interfacial characteristic / mechanical behavior