Influence of the beam oscillation parameters on the porosity of electron beam freeform fabricated titanium alloy SPT-2

The effect of electron beam oscillation on the formation of metal during electron beam freeform fabrication has received practically no attention. Nevertheless, it is a variable technological tool that allows to significantly influence the formation of metal during EBFFF process, including the probability of defects formation. The effect of the focus current, the form, and the frequency of the beam oscillation on the formation of pores in single beads by method of electron beam freeform fabrication of the titanium alloy SPT-2 on the substrate of the alloy VT6 was investigated. The porosity of the obtained beads was studied using x-ray images. It was found that too deep an arrangement of the focal plane relative to the substrate surface leads to excessive pore formation. Reducing the oscillation frequency from 1000 Hz to 100 Hz made it possible to completely get rid of the pores in the metal. The use of a spiral-shaped oscillation made it possible to reduce the probability of pore formation in comparison with an oscillation in the form of concentric circles.