Erokhin O. Production of microalloyed titanium alloys with oxygen and silicon by electron beam melting

Ph.D. Thesis is devoted to the solution of an important scientific and technical problem, lying in the development of the theory and practice fort high-quality ingots of microalloyed titanium alloys production by the method of electron beam melting with an intermediate capacity. By the method of mathematical modelling application, the processes of chemical elements evaporation during Electron Beam Melting (EBM) of titanium-based alloys have been researched. On the basis of calculations carried out within the framework of mathematical models, technical regimes have been determined and Electron Beam Melting (EBM) technology for microalloyed titanium ingots has been developed that ensures a high quality metal produced. Work has been carried out on the production of semi-finished products and the high quality of titanium alloys produced by the developed electron beam technology has been demonstrated. The peculiarities of titanium oxides dissolution processes in the titanium melt under vacuum conditions and the effect of electron beam heating have been studied. Study of ingots quality, structure and mechanical properties of titanium microalloyed with oxygen produced by the electron beam melting method have been carried out. The technology for producing ingots micro-alloyed with oxygen by application of Electron Beam Melting (EBM) method with an intermediate capacity has been developed. Exemplified by production of Grade 2 and Grade 3 titanium, the technology for producing large-sized ingots microalloyed with oxygen by the application of electron beam melting method with an intermediate capacity has been developed. Study of alloying components evaporation process features from ingots of microalloyed titanium alloys under vacuum conditions and the effect of electron beam heating has been carried out. Technology for producing ingots of titanium alloys microalloyed with silicon by the application of electron beam melting method with an intermediate capacity has been developed. The study of the ingots quality, structure and mechanical properties of the BT9 titanium alloy produced by the application of Electron Beam Melting (EBM) method with an intermediate capacity has been carried out and it has been demonstrated that this technology allows producing high-quality ingots both in terms of chemical composition and structure. It has been demonstrated that the penetration depth of the surface layer of heat-resistant titanium alloy ingots processed by electron beam melting technology reaches up to 10 mm, and the surface of the ingots has a high quality, mirror-like appearance with characteristic vacuum etching, smooth microrelief without cracks, breaks and interruptions. Research of mechanical properties of semi-finished products made from ingots of heat-resistant BT 9 titanium alloy melted by the application of Electron Beam Melting (EBM) method revealed that they meet all the requirements of the regulatory standards made by the industry for the metal quality of heat-resistant titanium alloys. Practical significance of the results obtained for Ph. D. Thesis research lies in the fact that a new promising technology has been developed, application of which for producing domestic semi-finished heat-resistant alloys based on titanium will allow to abandon the import of valuable foreign semi-finished products, and ensure the expansion of their use by Ukrainian enterprises. Furthermore, implementation of the developed Electron Beam Melting (EBM) technology for producing large-sized ingots with a regulated oxygen content opens up an opportunity for creating production of semi-finished products to manufacture the parts of powerful power plants. The developed Electron Beam Melting of the side surface technology of large-sized ingots will significantly increase the yield of usable material.