Microstructure and Properties of Ti-6Al-4V Articles 3D-Printed with Co-axial Electron Beam and Wire Technology

Abstract

Advanced additive manufacturing technology of direct energy deposition type called x Beam 3D Metal Printing was employed for manufacturing of articles of various size and shape using titanium Ti-6Al-4V alloy wire as a feedstock material. The key distinctive feature of this process is applying of the hollow conical electron beam generated by low-voltage (< 20 kV) gas-discharge electron beam gun for heating and melting of the substrate and wire, which ensures precisely controllable liquid metal transfer from the wire end to the substrate, specific temperature gradients at the fusion area and heat flow from liquid metal pool. Such conditions of heating, melting and cooling during deposition of molten additive material provide controllable microstructure formation, including grain size and material texture. Influence of processing parameters and cooling conditions on fusion, crystallization, grain growth and intragrain structure of manufactured “chunky” Ti-6Al-4V blocks was discussed. The post-processing heat treatment was used to relieve residual stresses formed during article manufacturing. Tensile and fatigue testing has been performed for samples cut in various directions of produced articles to investigate the material uniformity. Optimization of processing parameters allowed production of 3D printed articles from Ti-6Al-4V with isotropic microstructure and mechanical characteristics which met standard requirements for Ti-6Al-4V material.