Comparative Analysis of Structure and Mechanical Properties of Additive Objects Manufactured by Electron Beam Method and Cold Metal Transfer

Nowadays prototyping and additive manufacturing of objects are the most promising trends of development. As opposed to more precise powder methods, particular attention has been given to faster wire techniques, which allow manufacturing of objects without pores. This work compares the influence of two wire techniques, electron beam additive manufacturing and cold metal transfer, on the structure and mechanical properties of AMg5 aluminum alloy. Under optimum printing parameters, the powers of the electron beam and arc were close, however, due to the pulse pattern of the arc, the cold metal transfer was more cost efficient. In addition, the arc technique is carried out in an argon environment, which accelerates cooling of the applied layer. Generally, due to lower heat input and accelerated cooling, the grain structure is refined, which leads to an increase in strength and microhardness. Due to continuous removal from the substrate and an increase in the weight of the object, the heat conditions of application of the next layer vary, which is controlled by a decrease in beam/arc power. That said, each layer is characterized by its thermal history, thus influencing the structure and properties of the material. In particular, the higher the heat amount accepted by a layers from previous layers, the lower its strength. When a certain height is crossed (about 30 mm) the cooling is intensified, due to the higher weight of the object, and the strength increases again. This is the most characteristic for cold metal transfer. However, these oscillations are rather moderate; the mechanical properties along the height are highly stable in both techniques. In addition, in the case of cold metal transfer, burning of alloying magnesium is lower. In general, at present, the cold metal transfer is more cost efficient and allows one to manufacture objects of higher quality.