Beam Current Effect on Microstructure and Properties of Electron-Beam-Melted Ti-6Al-4V Alloy.

In this study, a noncommercial 3D printing machine was used to fabricate Ti-6Al-4V alloy by electron-beam melting (EBM). The influence of beam current on the microstructure, phase composition and mechanical properties of electron-beam-melted Ti-6Al-4V alloy was investigated. Numerical simulation is implemented to evaluate thermal fields during electron-beam melting of Ti-6Al-4V powder. The decrease in beam current from 3.5 to 2.5 mA leads to refinement of microstructure: The average width of α plates decreases from 10 down to 6 μm. The formation of finer microstructure is attributed to higher cooling rate at lower beam current confirmed by simulation. The phase composition of EBM Ti-6Al-4V indirectly depends on the beam current. High content of β phase (7%) was achieved at the beam current of 3 mA. The produced Ti-6Al-4V samples are characterized by high microhardness (470-520 HV). [ABSTRACT FROM AUTHOR]