Deposition of Ti–6Al–4V using laser and wire, part I: Microstructural properties of single beads

In this paper, the microstructural characteristics of Ti–6Al–4V single beads and their dependence on process parameters are addressed. Single beads represent the smallest – and therefore fundamental – unit of additive manufactured components. Bead-on-plates and single beads are produced using a 3.5 kW Nd:YAG laser and Ti–6Al–4V wire. Within 71 sets of process parameters laser beam power, welding speed, and wire-feed speed are varied. The microstructures are investigated by light and scanning electron microscopy, and are divided into several zones according to the thermal history underwent. Microstructural differences of the beads are correlated to the process parameters and discussed. The experiments reveal fundamental microstructural and process characteristics which are helpful for the repeatable and predictable manufacturing and understanding of multi-layered components.