Materials science

 

POSSIBILITIES OF CREATING NEW COMPOSITE MATERIALS FROM A CARBON FIBER MATRIX AND A WIRE FROM A TITANIUM NICKELIDE ALLOY WITH A HIGH ELASTIC PROPERTIES

 

D.E. Gusev, M.Yu. Kollerov, E.A. Lukina, R.E. Vinogradov

 

The mechanical behavior in bending of composite materials made of a carbon fiber matrix reinforced with a superelastic TiNi wire has been investigated. The influence of the number of carbon fiber layers and the volume fraction of reinforcing TiNi elements on the elastic characteristics (modulus of elasticity, proportionality limit and corresponding deformation) of the composite material is shown. An increase in the elastic and strength characteristics of the composite material is revealed when it is reinforced with a superelastic wire.

 

Keywords: NiTi, titanium nickelide, composite material, carbon fiber, mechanical testing, elastic deformation, superelasticity.

 

CREATION OF GRADIENT STRUCTURES IN LARGE-SIZED ENDOPROTHESIS BLOCKS MADE OF VT6 ALLOY BY THERMAL HYDROGEN TREATMENT

 

A.V. Neiman, A.M. Mamonov, E.O. Agarkova, A.V. Ovchinnikov

 

The possibility of the formation of a gradient structure in large-sized endoprostheses blanks made of VT6 titanium alloy by the methods of thermal hydrogen treatment has been investigated. It is shown that the resulting structure is represented by a finely dispersed mixture of α- and β-phases in surface layers up to 5 mm deep and a bimodal structure in the core. The formed structure provided a significant gradient of hardness over the section of the workpieces, with a level of at least 37 un. HRC in the surface layer.

 

Keywords: thermal hydrogen treatment, gradient structure, hardness, titanium alloys, endoprostheses

 

STUDY OF STRENGTH CHARACTERISTICS OF EXPERIMENTAL HEAT-RESISTANT PSEUDO-α TITANIUM ALLOY VT20

 

M.A. Gorbovets, S.A. Golynets, S.A. Monin, O.S. Kashapov

 

Tests were carried out to determine the strength characteristics of a new experimental heat-resistant pseudo-α titanium alloy. It was found that the characteristics of short-term and long-term strength, creep, and high-cycle fatigue experimental alloy surpasses the VT20 alloy of the same class and at the same time is not inferior to the two-phase VT9 alloy. The stress concentrator on notched specimens reduces the scatter of test results at the HCF and increases the scatter of test results at the MCF.

 

Keywords: titanium alloys, microstructure, mechanical properties, testing temperature, fatigue.

 

PREDICTION OF THE MECHANICAL PROPERTIES OF Ti-6Al-4V ALLOY BARS DEPENDING ON THE STRENGTH EQUIVALENTS FOR ALUMINUM AND MOLYBDENUM AT TEMPERATURES OF 20–600°C

 

Yu.B. Egorova, L.V. Davidenko, I.M. Mamonov, A.V. Shmyrova

 

Based on the analysis of production data the correlations of mechanical properties with the content of alloying elements and impurities, the diameter of the bars, and the structure parameters after annealing under industrial conditions of rolled, forged, and pressed bars with a diameter of 15–150 mm made of various modifications of the Ti-6Al-4V titanium alloy are investigated. Regression dependences for estimating the average values of the mechanical properties of bars on the strength equivalents of alloying elements and impurities for aluminum and molybdenum in the temperature range from 20 to 600°C are justified.

 

Keywords: chemical composition, bars, titanium alloy Ti-6Al-4V, mechanical properties, aluminum and molybdenum equivalents, annealing, forecasting.

 

EVALUATION OF THE OPERATIONAL RELIABILITY OF TITANIUM ALLOY CYLINDERS

 

S.V. Serikov

 

The work compares the performance of cylinders made of titanium alloys 14, VT14, with cylinders if they were made of titanium alloy PT7M. The calculated prospects of spherical cylinders made of PT7M alloy are shown. Especially when they are produced with a low specific weight, while observing a safety margin.

 

Keywords: cylinders, titanium alloys, ultimate strength, yield point, elongation, impact strength, specific work of fracture, intense load.

 

 

Manufacturing technologies

 

ABOUT IMPROVING THE QUALITY OF FORGINGS OF W-SHAPED BRACKETS MADE OF VT14 ALLOY

 

V.I. Galkin, P.A. Golovkin, S.A. Fesenko, E.A. Davydkina

 

Mathematical modeling of the process of stamping of W-shaped forgings of brackets from titanium alloy VT14 has been carried out. Methods for increasing the homogeneity of their structure by controlling the deformation pattern of the initial workpiece and the temperature of its heating are shown. It has been established that an increase in the uniformity of structural and phase transformations occurring in the process of forming a forging makes it possible to improve its quality and uniformity of mechanical properties without changing the die tooling and the equipment used.

 

Keywords: forging, part, deformation, structure, titanium alloy, deformation mechanisms, phase transformations, structural transformations, mechanical properties, crack resistance.

 

PROSPECTS FOR OBTAINING POWDERS OF ORTHORHOMBIC TITANIUM ALUMINIDES BY HYDROGENATION–DEHYDROGENATION

 

K.S. Senkevich, O.Z. Pozhoga

 

The possibility of obtaining fine powders from the intermetallic titanium alloy VTI-4 by the method of hydrogenation–dehydration has been studied. It has been established that ball milling of rapidly quenched fiber from the alloy hydrogenated to 2 wt. % hydrogen makes it possible to obtain a fine powder of intermetallic hydride. Subsequent vacuum annealing leads to the decomposition of the hydride and obtaining a powder of an intermetallic alloy with a single-phase β-composition.

 

Keywords: Orthorhombic titanium aluminide, rapid solidified, powders, hydrogenation–dehydrogenation.

 

HIGH-VOLTAGE POWER SUPPLIES FOR ELECTRON-BEAM TECHNOLOGICAL INSTALLATIONS

 

G.M. Mustafa, S.V. Chistilin, A.B. Ermakov, S.I. Gusev

 

The issues of using high-power high-voltage power sources (HVPS) for technological installations of electron-beam melting of metals are discussed. The use of an intermediate frequency of energy conversion made it possible to minimize the weight and overall dimensions of the VIP and significantly improve their operational characteristics. Isolated Gate Bipolar Transistors (IGBTs) are used as the element base of the frequency converters. Transformers-rectifiers are made on the basis of ferrite magnetic cores with dry air-barrier insulation. The article describes the designs and characteristics of the HVPS for a voltage of 30–40 kV with a power of 150–450 kW, created in the Scientific and Production Enterprise "NPP LM Inverter" LLC.

 

Keywords: intermediate frequency, technological short circuit, automatic re-activation.