Investigations on Additive Manufacturing of Ti–6Al–4V by Microplasma Transferred Arc Powder Deposition Process

Abstract

This paper presents investigation findings on additive manufacturing (AM) aspects of Ti6Al4V by microplasma transferred arc powder deposition (μ-PTAPD) process in continuous and dwell-time mode. Pilot experiments were conducted to identify feasible values of six important parameters of μ-PTAPD process for single-layer deposition followed by 27 main experiments varying three parameters. Energy consumption aspects were used to identify optimum values of parameters varied during main experiments for multilayer deposition. It revealed that higher values of flow rate of powder and travel speed of deposition head result in smaller values of power consumption per unit flow rate of powder and energy consumption per unit traverse length. Continuous and dwell-time modes were used to study deposition characteristics, microstructure, lamellae widths, wear characteristics, tensile properties, fractography of tensile specimen, wear mechanism, and microhardness of multilayer depositions. Dwell-time deposition yielded higher effective wall width (EWW), deposition efficiency (DE), yield strength, ultimate strength, microhardness, surface straightness, lower strain, wear volume and friction coefficient, and smaller lamellar width. It had good deposition quality with fine partial martensite and basket-weave microstructure. Fractography analysis exhibited fine dimple rupture for dwell-time multilayer deposition and occurrence of elongated regions for continuous multilayer deposition. Wear of dwell-time multilayer deposition occurred by microploughing and microcutting resulting in smaller wear debris. Comparison of Ti6Al4V depositions by different processes revealed that dwell-time μ-PTAPD process is cost-effective than laser-based processes and energy efficient than pulsed plasma arc process.