Structure and Phase Composition of Ti–6Al–4V Alloy Obtained by Electron-Beam Additive Manufacturing

Abstract

The paper presents the fabrication of Ti–6Al–4V alloy specimens using two operating modes of the electron beam additive manufacturing (EBAM). The structure, phase composition and microhardness of the obtained alloy specimens are investigated. The EBAM process includes a deposition of Ti–6Al–4V wire onto a substrate comprising of VT1-0 (grade 2) titanium alloy and 12Kh18N10 (AISI 321) stainless steel. It is shown that at a high electron beam current, the height and width of the β-phase columnar grains are lower than at a low electron beam current. This phenomenon is discussed in terms of stabilization of the temperature gradient and the increased cooling rate during the building process. This phenomenon is caused by the formation of Fe₂Ti, FeTi and Cr₂Ti intermetallic phases in the diffusion bonding appeared between the titanium and stainless steel plates.