Process parameters optimisation of Ti6242 produced by Electron Beam Melting

Titanium and its alloys are used in a wide range of applications such as aerospace, marine, biomedical implants and consumer goods, thanks to their superior specific strength, excellent corrosion resistance, and biocompatibility. However, from manufacturing point of view, the titanium alloys suffer of several problems, mainly due to the reactivity to oxygen. The introduction of oxygen results in the simultaneous formation of an oxygen layer (alpha-case) , it forms during casting, processing, and elevated temperature exposure in service. This oxide layer formed during service often limits the maximum service temperature of titanium alloys. Thanks to the controlled environment, Additive manufacturing processes have already demonstrated the capacity to produce Titanium alloys with superior quality respect to the conventional manufacturing processes. In this contest, Electron Beam Melting (EBM) which works in a vacuum build environment and high build temperature is extremely attractive to minimize residual stress, oxide formation and material contamination. However, EBM research is mainly focus on Ti6Al4V, while alloys, such as Ti6242, that are wider applicability at higher temperature applications and excellent fatigue and creep resistance are rarely explored. The presented work aimed to explore the process window of Ti6242 by EBM process. The focus was to understand the influence of process parameters (in particular beam speed, current, focus offset and line offset) on the final microstructure and the material density. The surface finishing measured as surface roughness and dimensional accuracy as function of process parameters has been analysed using descriptive and inferential statistical analyses in light of producing a representative industrial component.