Titan №4 2019

Materials science

 

INFLUENCE OF PROCESSING TECHNOLOGY ON STRUCTURE AND CORROSION RESISTANCE OF A PILOT TITANIUM ALLOY WITH HIGH ALUMINUM CONTENT

 

S.S. Slezov, A.A. Mamonov, А.А. Lidzhiev, E.O. Agarkova, Yu.V. Chernyshova

 

The influence of a complex processing technology a pilot Ti-8.7Al-2.0Mo-1.5Zr titanium alloy is investigated including thermohydrogen treatment, vacuum ion-plasma nitriding and deposition of titanium nitride coating. It is shown that the structural state of the material bulk formed by thermohydrogen treatment as well as surface modification obtained by vacuum ion-plasma nitriding and titanium nitride coating significantly improve the corrosion characteristics of the alloy samples in a 0,9% NaCl aqueous solution. Processing modes are determined that provide the minimum current density of the passive state at potentials up to 1500 mV.

 

Keywords: titanium alloy, thermohydrogen treatment, vacuum ion-plasma nitriding, nitride coating, corrosion.

 

FORECASTING OF MECHANICAL PROPERTIES OF RODS FROM VT6 ALLOY DEPENDING ON CHEMICAL COMPOSITION AND ANNEALING REGIME

 

Yu.B. Egorova, S.V. Skvortsova, L.V. Davidenko, E.V. Chibisova, O.N. Gvozdeva

 

The results of statistical researches of the dependence of the mechanical properties of rolled rods with a diameter of 15–150 mm from a titanium alloy VT6 on their chemical composition and modes of simple (ordinary) annealing are presented.  Multifactor regression dependencies were established for the evaluation of short-term mechanical properties from equivalents of alloying elements and impurities in aluminum and molybdenum, the difference between the polymorphic transformation temperature and the annealing temperature, the annealing time, the diameter of the rod.

 

Keywords: titanium alloy VT6, rolled rods, chemical composition, structure, mechanical properties, statistical studies, forecasting.

 

RARE-EARTH ELEMENTS EFFECT ON THE STRUCTURE AND PROPERTIES OF ORTHORHOMBIC TITANIUM ALUMINIDE BASED ALLOY

 

A.V. Novak, N.A. Nochovnaya, E.B. Alekseev

 

The rare-earth elements Y, Gd, and Sc effect on the structure and properties of the alloy Ti–22.4Al–23.6Nb–0.9Zr-1.82 (V + Mo + Ta) –0.15W–0.4Si (at. %) was studied. The REE introduction leads to the formation of a finer-grained homogeneous ingots macrostructure and an increase in the dispersion of the secondary lamellar O-phase in the microstructure that forms after thermomechanical treatment. The gadolinium introduction ensures the achievement of the highest level of strength, plastic and heat-resistant properties of the alloy.

 

Keywords: titanium aluminide, Ti2AlNb, orthorhombic alloy, rare-earth elements, structure, mechanical properties.

 

 

Processing technologies

 

THE STRUCTURE AND PROPERTIES OF TITANIUM ALLOY VT6 OBTAINED BY DIRECT LASER DEPOSITION USING SECONDARY POWDER

 

S.A. Shalnova, O.G. Klimova-Korsmik, M.O. Gushchina, A.M. Vildanov, G.A. Turichin

 

Due to economic benefits, including material savings during direct laser deposition, it is possible to obtain products using a mixture of primary and recycled powder. Part of the powder during direct laser deposition does not fall into the melting zone, which significantly reduces the utilization of the material. In order to determine the effect of the recycled powder on the quality of titanium products, we studied the grown samples made from mixtures with different ratios of primary and recycled powders.

 

Keywords: high-speed direct laser deposition, additive technologies, titanium alloys.

 

USE OF V-Al-C PRECURSOR IN MELTING A V-Al-N-C MASTER ALLOY

 

D.V. Taranov, A.V. Larionov, S.V. Zhidovinova, V.M. Chumarev, A.N. Rylov, M.V. Trubachev

 

The possibility of using the V (70) -Al (23) -C (7) precursor alloy as a carbidizer for out-of-furnace aluminothermic smelting of the V-Al-N-C master alloy is studied and verified. It has been established that the replacement of carbon in the smelting charge with the V (70) -Al (23) -C (7) precursor does not lead to a change in the phase composition of the master alloy and the uniform distribution of carbide and nitride inclusions in the bulk of the ingot. The nitrogen-containing phase of the master alloy is represented only by aluminum nitride, the carbon-containing phase - in the form of non-stoichiometric V2AlC carbide. The oxygen content in the ingot (0.06 %) meets the requirements of technical specifications for the V-Al-N-C master alloy.

 

Keywords: V-Al-N-C master alloy, precursor, aluminothermy, phase composition, microstructure

 

THE APPLICATION EFFICIENCY OF THREE-ROLL GROOVES FOR ROUND TITANIUM RODS ROLLING

 

А.Y. Postylyakov, Y.V. Inatovich, Y.N. Loginov

 

The results of finite-element modeling of rolling round rods from VT6 titanium alloy according to the schemes circle ‒ oval ‒ circle and circle ‒ lancet triangle ‒ circle are presented. The values оf deformations and temperatures in the sections of the intermediate and final profile are determined, a comparative analysis of the nature of their distribution is performed. The specific energy costs during rolling according to both schemes are calculated. It has been established that the use of three-roll gauges is more effective both in terms of uniformity of the deformed and thermal state of the rolled bar, and energy consumption for deformation.

 

Keywords: shape rolling, roll pass design, gauge systems, two-roll grooves, three-roll grooves, deformed state, temperature, specific energy costs

 

 

Application. Quality. Market

 

THE TITANIUM FASTENING PARTS. THE EXPERIENCE OF THE DESIGNING AND USAGE

 

V.V. Travin, S.G. Temkin, A.I. Zmozhniy, G.A. Shevelev

 

The basic principles for designing high-loading threaded connections of the power equipment are described. The results of the experiments for strength, stress relaxation durability, stability at the screwing and fasteners wear of the high strength titanium alloys are represented. The data about the antiscore coatings and grease for the contact surfaces is given too. The experience of the freedom from failure usage of the threaded and flange connections included in the responsible casing and rotor elements of the steam turbine plant has confirmed the proper approach about usage titanium alloys in that elements.

 

Keywords: threaded connection, titanium alloy, stress relaxation, wear, coating, grease.

 

TITANIUM POWDERS: CURRENT STATE OF TECHNOLOGIES AND MARKET

 

G.A. Kolobov, A.V. Ovchinnikov, A.V. Osipenko, V.V. Pavlov, V.O. Panova

 

Technologies of manufacturing titanium powders of various types are reviewed. To produce powders of nonspherical shape, the technology of hydrogenation-dehydrogenation with use titanium sponge and waste as raw material is applied. The powders of spherical shape are produced by technology of rotating electrode in plasma, gas and plasma atomization, Armstrong Process, as well as by technologies of Praxair and Metalysis companies. When the market of titanium powders is considered, volumes of production by different countries and applied technologies, as well as spheres and specific objects of application of products from various powders are shown.

 

Keywords: titanium powders, properties, technologies of manufacture, volume of production, application

 

 

Events and anniversaries

 

In memory of Alexander Ilyin