Aim of the work is development of technology of production of ingots from sparsely-alloyed titanium alloys using electron beam melting method. To get high mechanical characteristics in titanium alloy, the modifiers of high-dispersion carbide compounds were used as foundry alloys. They in process of electron beam melting provide strengthened with nanoparticles structure of a material suitable for further deformation processing. In order to develop nanosized alloying modifiers for high-strength titanium alloys there were synthesized nanosized powder in form of carbon solution in silicon-carbide. A technology was developed for production of ingots from sparsely-alloyed titanium alloys using electron beam melting method. The works on production of 200 mm diam. titanium ingots with addition of 0.5% and 1.5% of the alloying modifiers based synthesized nanosized silicon-carbide were carried out with the help of determined modes. Hot deformation processing of ingots was performed, 15 mm thick deformed sheets were produced and then subjected to further heat treatment. Structure and properties of obtained material were investigated.
This paper reports a comprehensive study that investigated the quality of heat-resistant titanium alloys VT3-1 and VT9 obtained by the method of electron beam melting (EBM). It is shown that EBM makes it possible to produce high-quality metal of ingots of heat-resistant titanium alloys VT9 and VT3-1. Semi-finished articles were made in the form of bars from ingots obtained by the EBM method. It was established that in the macrostructure of the deformed metal there are no cracks, delamination, cavities, metal and non-metallic inclusions. The macrostructure of the metal of the bars corresponds to 4 points for the alloy VT3-1 and 4–5 points for the alloy VT9 on the 10-point scale of microstructures of instruction 1054-76. It was shown that the metal microstructure of forged bars of VT9 alloy consists of primary β grains with a continuous or intermittent α-rim along the grain boundaries 3–4 μs thick. The structure of the metal in the volume of grain – lamellar type with partially globularized plates of the α phase, plates of α-phase of close orientation form α colonies measuring 10–40 μs. The thickness of the α plates is 1–5 μs, between the plates or globules of the α phase there is a layer of β phase with a thickness of 1–2 μs. The microstructure of the deformed metal of titanium alloy VT3-1 consists of primary β grains, the volume of which contains colonies of lamellar α phases measuring 10–100 μs. The thickness of α plates is 1.5–3 μs, the layer of β phase in the intervals between α-plates is mainly 0.3–0.5 μs. The microstructure of semi-finished articles in the form of deformed bars of alloys VT9 and VT3-1 corresponds to type 4–6 according to the 9-type scale of the microstructure of instruction 1054-76. Studies of the mechanical properties of the obtained semi-finished articles have shown that they meet all the requirements of regulatory standards that are put forward by industry to the quality of the metal of heat-resistant titanium alloys
Performance of scientific-technical researches at the E. O. Paton Electric Welding Institute of the NAS of Ukraine have been directed on development of technology for manufacture of titanium aluminide –based alloys using the method of electron-beam melting (EBM). The mathematical models of heat state and evaporation of alloying elements in EBM were developed. The results of calculations of heat state using the mathematical model allowed determining a dependence of depth of liquid pool on different melting rates. The mathematical models of processes of evaporation in EBM of titanium aluminide ingots were used for plotting the nomograms, which help to determine the necessary content of alloying element of the alloy in the initial charge for acquiring the necessary concentration of this element in ingot at set technological parameters of melting. In scopes of designed mathematical models there were investigated different technological modes of electron-beam melting of ingots based on titanium aluminide. The optimum EBM modes, at which a solidification front approaches to flat, were determined. At that, more uniform distribution of the additives on ingot section and volume is provided as well as level of stressed state is reduced. The works were carried out on manufacture of titanium aluminide based-ingots with addition of refractory as well as volatile alloying elements. Composition and structure of produced ingots were examined. It is shown that electron-beam melting allows getting chemically homogeneous ingots based on titanium aluminide and is a perspective method for production of such class materials.
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