Titan №1 2023

Raw materials. Metallurgy.

Fundamental problems of enrichment of quartz-leucoxene sandstones of Timan with obtaining high-quality titanium raw materials

G.B. Sadykhov, K.G. Anisonyan, Yu.V. Zablotskaya, T.V. Olyunina, D.Y. Kopyev, K.V. Goncharov, B.G. Balmaev, A.S. Tuzhilin

The article provides a detailed analysis of the results of research conducted by various organizations, from the second half of the twentieth century to the present, on the enrichment of quartz-leucoxene sandstones of the Yareg and Pyzhem deposits of Timan in the Komi Republic.

In the Southern Timan (Yareg deposit), sandstones are predominantly leucoxene with an insignificant content of altered ilmenite. In the Middle Timan (Pyzhemskoye deposit), sandstones are ilmenite-leucoxene, but with the predominance of the latter. In sandstones, leucoxene and ilmenite grains have a sagenite structure, in which titanium oxides (rutile, anatase, pseudorutyl, etc.) are in close fusion with finely dispersed quartz. The SiO2 content in leucoxene grains is 25–35%, and in ilmenite grains – 15–20%. The main cementing bond in sandstones is siderite. When sandstones are enriched using flotation and gravity methods, there is no separation of quartz and leucoxene, at best, leucoxene concentrates with a very high quartz content (40–45% and higher) and with large losses of titanium are obtained.

The main reasons for the low efficiency of flotation, gravity and other physical methods of enrichment for the separation of quartz and leucoxene are discussed, and the developed scientifically based integrated approaches to solving the problem of enrichment of quartz-leucoxene sandstones of Timan with the production of high-quality titanium raw materials for the production of titanium and pigment TiO2.

Keywords: leucoxene sandstones, Yareg deposit, Pyzhem deposit, siderite bundle, hydrothermal processes, leucoxene, leucoxenized ilmenite, quartz, magnetizing firing, desilinization of leucoxene and ilmenite, artificial rutile, synthetic wollastonite, calcined quartz sand.

Materials science

The research of the influence of heat treatment on residual stresses, mechanical properties, and texture formation of VT6 alloy specimens produced by selective laser melting

S.V. Skvortsova, A.E. Ivanov, V.S. Spektor, A.V. Shalin, P.A. Smirnov

The paper describes the study of titanium alloy samples obtained by selective laser melting. The influence of different annealing temperatures on the magnitude of residual stresses was compared. The texture was compared, as well as the influence of annealing temperature on texture formation and mechanical properties of titanium samples grown in different directions.

Keywords: titanium alloy, additive technologies, heat treatment, residual stresses, texture formation.

Structure and properties of  pseudo-α titanium alloy produced by hot isostatic pressing (HIP)

A.S. Oryschenko, V.P. Leonov, I.M. Khachaturyan, Yu.Yu. Malinkina, M.V. Iksanov, S.N. Petrov, D.A. Karyagin

The powder of pseudo-α-titanium alloy PT-3V, obtained by the plasma rotating electrode process (PREP), has been studied. It is characterized by a high degree of sphericity and the almost complete absence of satellites; the microstructure of the powder material has a finely dispersed lamellar structure. Compact parts were produced from the powder. The mechanical properties of both the test samples and the experimental model fully comply with the requirements of the regulatory documentation for deformable semi-finished products of similar sections.

Keywords: pseudo-α titanium alloy, powder material, PREP, hot isostatic pressing.

Forging effect on structure and surface quality in the machining of billets made of Ti-6Al-4V titanium alloy

P.A. Golovkin, A.V. Krykov

At the present time, there are no regulatory documents that would determine the feasible ways to manufacture parts from titanium alloys, from the choice of the type of initial material to its machining in terms of obtaining a quality surface and structure. On the example of titanium alloy Ti-6Al-4V the dependence between the type of blanks - bar or forging, and the quality of the surface of the part turned through has been revealed. It is shown that forging improves the quality of machining and eliminates some inherent material deficiencies of the original rolled bars.

Keywords: titanium alloy, bar, forgings, pieces, temperature, structure, workability, surface quality, cutter load, hardness of material.

Manufacturing technologies

Features of manufacturing titanium alloy castings by centrifugal casting

M.N. Saubanov, I.O. Leushin, I.E. Illarionov

For the manufacture of investment castings from titanium alloys by centrifugal casting, it is necessary to conduct an experimental study and calculations of the elements of the gate system, taking into account the chemical activity of titanium in the molten state and the inertia of the materials of the mold. In this paper, the optimal hydraulic modes and operating conditions and designs of individual elements of the gate system concerning centrifugal casting of titanium alloy castings are determined. Taking into account the relative and Coriolis acceleration of the liquid titanium melt reveals the possibility of intensifying the processes of floating light particles by installing feeders of a special curved shape.

Keywords: titanium investment castings, centrifugal casting, chemical activity of titanium alloys, design of gate systems, portable rotational, relative, Coriolis acceleration.

Processing technologies

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Deformations during cold rolling of titanium alloy pipe

Yu.N. Loginov, A.Yu. Postylyakov, F.V. Vodolazskiy, Ya.I. Kosmatskiy

Numerical simulation of the process of cold rolling of a Ti-3Al-2,5V (Grade 9) titanium alloy pipe is performed. It has been established that in the final product, the deformations are much higher than the values calculated through the geometry of the workpieces before and after deformation, and this difference exceeds 250%. This can create an error in predicting the level of work hardening of the metal towards the end of the rolling process. An inhomogeneous distribution of the strain in the cross section of the finished pipe was revealed both in the direction of the radius (along the wall thickness) and in the tangential direction. A strong decrease in the strain according to von Mises with respect to the intensity of deformation was also revealed, which indicates a high degree of nonmonotonicity of the rolling process.

Keywords: titanium alloy, plastic deformation, cold rolling of pipes, modeling, finite element method.