Development of electron-beam equipment and technology for additive layer-wise wire cladding

Currently, a wide range of additive technologies (or 3D printing technologies) are increasingly often used to obtain metal products of complex shape with anisotropic properties. A thick-walled part can be printed with less but sufficient precision (a few millimeters) and greater productivity by three-dimensional electron beam cladding with wire. The technology is based on a vacuum chamber with an electron-beam gun with a plasma emitter and modular manipulators, which enables layer-by-layer electron-beam melting (EBM) of powders or three-dimensional deposition of melted wire. Included software provides modular exchange and synchronized control of all system components according to the task using digital G-codes. The experimental printing was carried out at an accelerating voltage of 30 kV and a beam current from 15 to 20 mA. In this work, the samples from wires of Ti-6Al-4V titanium alloy and AISI 308 steel were printed on an electron-beam 3D-printer. The quality of the samples in terms of porosity and, hence, the mechanical properties was studied by non-destructive (computed tomography) and mechanical testing. It is shown that selecting proper modes of radiation exposure, wire feeding and beam scanning allows obtaining titanium and steel products with satisfactory mechanical properties. However, the problem of reducing macro porosity, especially for the titanium alloy, requires new approaches to optimizing the microstructural uniformity and porosity.