Determining the structure and properties of heat-resistant titanium alloys VT3-1 and VT9 obtained by electron-beam melting

Abstract

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