Determining the technological parameters of electron-beam welding of high-strength titanium alloys

Abstract

It is usually quite difficult to carry out deep penetration of thick-walled products from titanium alloys using conventional welding technologies. In this study, it was proposed to use electron beam welding under high vacuum conditions for the realization of 40 mm thick melting of VT23, VT3-1 alloys. This paper considers the possibility of obtaining high-quality welded joints from high-strength titanium alloys having (a+β) two-phase structures. For the implementation of research works, samples were made from selected materials, samples were welded according to the specified modes, metallographic analysis was performed, and the level of mechanical properties was determined. The research results were verified under laboratory conditions. The technological features of the processes of electron-beam welding of products with a thickness of 40 mm were considered; the parameters affecting the weldability of titanium alloys and their structure were determined. The welded samples were checked by X-ray non-destructive testing, the microstructure of the welds was studied, and the physical and mechanical properties of the welded joints were checked. It was established that a feature of titanium alloys VT3-1, VT23 is the need for heat treatment after welding under the base metal regimes to improve the characteristics of the welded joint. The resulting strength limit of the alloys after heat treatment reached values of 1250 MPa and more, while the impact toughness was at the level of 48–50 J·cm-2. Modeling the welding process has made it possible to ensure the reproducibility of the characteristics of the welded joint at a level close to that of the base metal, to increase the quality indicators of welded joints, and to reduce the time required to test the technology. The studies of simulator samples showed compliance of the quality of welded joints with the predefined parameters.