Cost-Effective Manufacturing of Ti-6Al-4V Filler Wire from As-Cast Ingot via Processing Map-Guided Design for Wire Arc Additive Manufacturing

Abstract

Wire and arc additive manufacturing (WAAM) is a cost-efficient technology for large-scale production; however, the high cost of Ti-6Al-4V filler wire, primarily associated with conventional billet-based thermomechanical processing, remains a critical limitation. This study proposes a direct and cost-effective manufacturing route for Ti-6Al-4V filler wire from an as-cast ingot, enabled by processing map-guided thermomechanical design. Hot deformation behavior was systematically investigated for the as-cast ingot, the β-forged billet, and the α + β-forged billet over 700–1200 °C and strain rates of 0.01–10 s−1. An artificial neural network (ANN)-assisted correction was employed to compensate for adiabatic heating, enabling reliable construction of processing maps and identification of stable deformation domains associated with dynamic recrystallization (DRX). The optimized deformation conditions derived from the processing maps were directly applied to hot-rolling, followed by room-temperature wire drawing. As a result, high-quality Ti-6Al-4V filler wire with a diameter of 1.7 mm was successfully fabricated. Microstructural analysis revealed deformation-induced refinement and alignment of the α phase, with variations depending on the initial state. Despite relatively coarser features, the wire fabricated from the as-cast ingot exhibited a tensile strength of 1408 MPa and elongation of 6.7%, demonstrating tensile properties comparable to those of the wires fabricated from the forged billets. These results provide direct experimental validation that processing map-guided design enables the direct conversion of as-cast Ti-6Al-4V ingots into high-quality filler wire. The proposed approach offers a simplified and economically competitive alternative to conventional billet-based processing routes for WAAM applications.