A concept is developed for assessing the stability of untransformed austenite entering the martensite-austenite component of a bainitic structure, which is determined by the action of hydrostatic stresses caused by difference in the specific volumes of the austenite and ferrite phases. Relations describing the thermal stability of austenite in the M/A phase are derived. The former is affected by the

A model of growth kinetics of CoB and Co2 B layers on cobalt alloy ASTM F-75 at 1223 – 1273 K is developed using two different approaches. The first approach is based on numerical solution of Fick’s equations inside each phase (Co2B, CoB and Co) using front tracking analysis with an implicit scheme. The second approach is based on an integral method employing numerical solution of differential algebraic

The influence of the initial structure parameters on formation of austenite grains under heat treatment of pearlitic spring steels is studied. Metallographic and x-ray diffraction analyses are performed. The structural characteristics of the austenite, i.e., the conventional grain diameter, the diversity of grain sizes, the nonequiaxed condition, the inhomogeneity, and the dislocation density, are

The surface layer obtained by ion-beam stirring of a thin carbon film deposited on titanium alloy VT6 is studied. The composition and the chemical condition of elements in the surface layer are determined. Formation of a disordered carbon structure in a thin surface layer (20 – 40 nm) and of titanium carbides in the transition layer is detected. A model of formation of structure in the specimens during

The effect of the content of Cu, Pb, Fe, Sn and Si on the properties of 445 commercial batches of brass ribbon subjected to continuous annealing to a soft condition is studied. The active system of control of the composition and properties of processed batches is updated, and a regression dependence of the properties of the ribbon on the content of lead, iron, tin and silicon impurities in it is determined

Processes of amorphization and crystallization of binary and multicomponent melts based on transition metals are studied. Comparative analysis of the pre-crystallization structural changes and of the atomic dynamics under the conditions of forced quenching and deep supercooling of metallic melts is performed. It is shown that hydrogenation of the melts introduces specific features into the occurrence

The influence of the initial structure on formation of austenite, evolution of structure, and elevation of operating characteristics of steel SA508 Gr.3 (0.24% C, 1.40% Mn, 0.88% Ni, 0.54% Mo) after an intercritical heat treatment (IHT) is studied. After the IHT, the grain size of the hypoeutectoid ferrite in the steel with an initially ferritic-bainitic structure is much larger than in the initially

The boundary conditions for describing the mass transfer of carbon from a low-pressure oxygen-free atmosphere into steel under vacuum carburizing are analyzed. Experimental results and thermodynamic calculations are used to determine the numerical value of the activity of carbon in an environment of low-pressure acetylene. The calculated value of the carbon potential is used in the boundary condition

The possibility of raising the impact toughness of medium-manganese TRIP-steel Fe – 0.2% C – 6% Mn – 3% Al by application of a novel heat treatment involving quenching from the intercritical temperature range and subsequent tempering is investigated. Electron microscope and x-ray diffraction studies are performed after the heat treatment. The quenching mode providing the highest impact toughness is

The effect of metallurgical inheritance on the structure and mechanical properties of semiproducts from alloy 01570 of the Al – Mg – Sc system is studied by x-ray phase analysis, electron microscopy, x-ray energy dispersive analysis, tensile tests and electron fractography. The structure of the ingot and the conditions of the deformation and of the heat treatment are shown to affect the structure and

Samples of titanium alloy VT6 obtained by the method of cold gas dynamic spraying (CGDS) and subjected to hot isostatic pressing (HIP) for lowering the porosity and improving the mechanical properties are studied. The HIP is conducted at a temperature of 900°C and a pressure of 110 MPa. This reduces the volume fraction of pores from 8 to 0.5% and raises the ultimate strength of the samples from 70

The effect of various aging modes and preliminary tension (3%) on the microstructure and mechanical properties of Al – Li alloy 2A97-T3 (1.31% Li, 3.55% Cu, 0.37% Mg, the remainder aluminum) is studied. Scanning electron microscopy in combination with energy-dispersive spectroscopy and EBSD analysis are applied. The ultimate tensile strength is determined.

The effect retrogression and re-aging (RRA treatment) on the tensile properties in the transverse direction of extruded rods from aluminum alloy AA7049 is investigated. Transmission electron microscopy is used to study the structure and the phase transformations occurring in the alloy under the RRAtreatment. The conductivity of the alloy is measured in different conditions. It is shown that the RRA

The effect of phosphorus and carbon on crystallization and magnetic properties of iron-based soft magnetic amorphous alloy containing up to 22 at.% B is studied. Ribbons with compositions FeaSi6B22PbCcNb0.85Cu0.65 (a = 68, 66, 64 and 62; b = 2.5, 1.5, 1.25 and 1; c = 0, 3, 2.25 and 7.5) are fabricated by melt spinning. Crystallization of the alloy under heating and its properties are studied by x-ray

Nanoparticles of nonstoichiometric magnetite obtained by controlled oxidation of carbonyl iron (α-Fe) in water are studied. The Fe : H2O mole ratio is 3 : 4, 4 : 4 and 3 : 10. The particles are synthesized in a high-power Activator 2S mill in an air atmosphere by 24-h milling. X-ray diffraction and spectrum analyses of the synthesized magnetite nanoparticles are performed. Formulas describing the crystal

The softening of a hot-deformed die steel under thermocycling used in thermal fatigue tests is studied. The changes in the microstructure, in the dislocation structure and in the hardness of the surface layer and of the core of the thermocycled sample are analyzed. It is shown that the thermocycling process is accompanied by softening of the hot-deformed die steel, because the total concentration of

The microstructure, the phase composition, the microhardness and the wear resistance of hypoeutectic white cast irons with different contents of chromium are studied. It is shown that the wear resistance of the iron depends substantially on the type of the carbide phase and on the morphology of the ledeburitic eutectic, which is determined in its turn by the content of chromium.

The influence of preliminary low-cycle overloads on the fatigue fracture resistance in the stages of formation and propagation of cracks in cyclically hardened steels is studied. The regular features of changes in the structural state under the overloads and its relation to the stress-strain diagram are determined using metallographic and x-ray diffraction analyses. The prehistory of the process of

The characteristics of the oxide layer deposited by microarc oxidation (MAO) on Al – Si alloys in a silicate-alkaline electrolyte are studied. The thermal conductivity of the layer at 50 – 120°C is determined using a special facility by the method of stationary heat flow. The thickness, the porosity, the elemental composition, the content of the amorphous phase, and the size of the crystallites in

The structural types of copper, diamond and tungsten are represented by a linear union of four tetrahedrons over faces within solution of a general problem of representation of a crystal structure as a union of special atomic clusters. This union (a tetrablock) plays the role of a universal building unit, because it determines the generating clusters (building units) of the basic structural types considered

A process of manufacturing of rolled sheets from a new high-strength wear-resistant weldable steel H500 MAGSTRONG® with wear resistance, strength and impact toughness parameters at negative temperatures not inferior to those of the best world counterparts is described. Transmission electron microscopy is used to study the structure of a sheet with a thickness of 12 mm formed as a result of hot rolling

Examination of fractures of rolling bearings from steel 8Kh4V9F2-Sh (ÉI347-Sh) is used to assess the effect of production factors on the operating capacity of bearings under elevated loads. The microstructure and fractures of the steel are analyzed. The compressive stresses and the contents of the general and diffusion-mobile hydrogen are determined. It is shown that a fatigue crack appears in the

The main mechanisms of structure formation in zones of welded joints of unlike metals (steel – aluminum) obtained by friction stir welding in the mode of structural superplasticity are considered. Sheet billets of different steels (St3ps, 12Kh18N10T) and deformable aluminum alloys (AD1, AMg6) with a thickness of 3 mm are butt- and lap-welded by the friction stir technique. The microstructures, the

The methods of optical and electron microscopy and x-ray spectrum microanalysis are used to study the microstructure and phase composition of a tubular welded joint from alloy HP40NbTi based on the Fe – 25Cr – 35Ni system. Short-term and long-term mechanical properties of the alloy are determined. The joint is characterized by structural inhomogeneity and formation of silicon segregations and G-phase

The structure, phase composition and impact toughness of specimens cut from different-thickness regions of a billet with cross section 160 × 160 mm from continuously cast high-speed steel R6M5 are studied. It is shown that the macro- and microstructure, phase composition, and process ductility of the continuously cast high-speed steel R6M5 are substantially higher than those of the steel obtained by

The effect of heat treatment parameters (the temperature of 850 – 930°C and the cooling rate of 1 – 20 K/min) on the microstructure and mechanical properties of carbon steel with 1.95 wt.% C is studied. The temperatures of the phase transformations in the steel are determined. X-ray diffractometry is performed. A heat treatment mode preventing the formation of ledeburite in the structure of the steel

Long-length bimetallic conductors with a copper core and a shell from an aluminum alloy up to 2.4 mm in diameter with enhanced strength are obtained by swaging. The effect of the swaging strain on the structure, phase composition and mechanical properties of the bimetallic conductors is studied.

An approach to description of the structural types of phases is suggested, in accordance with which the structural types A15, C15 and C14 of Frank–Kasper phases are described as the densest packing of chains of special unions of tetrahedrons-tetrablocks. A tetrablock is a seven-vertex union of four tetrahedrons over faces. For the packing to be the densest, the ideal tetrahedrons in the tetrablocks

The process of formation of a multilevel multilayer B4C – Ti-6Al-4V cermet coating by the method of SLM is studied. The coating is characterized by presence of heterogeneous zones differing in the mechanical properties. It is shown that the use of the B4C – Ti-6Al-4V powder mixture with ceramics concentration 20 wt.% is not expedient, because it causes deficit of the metallic matrix and formation of

The relative magnetic permeability and electric conductivity in the temperature range from room one to 800°C are determined for steel 18CrNiMo7-6 with different structures, i.e., martensitic, bainitic and ferritic-pearlitic ones. The variation of the magnetic properties of the steel as a function of the temperature and of the microstructure and their effect of the depth of penetration of eddy currents

The methods of scanning electron microscopy and x-ray diffractometry are used to study the microstructure and mechanical properties of welded joints from alloy Ti60 after laser welding and subsequent heat treatment (PWHT). It is shown that the microstructure of the welded joint consists of three zones, i.e., a fusion zone (FZ), a heat-affected zone (HAZ) and base metal (BM). The PWHT lowers considerably

The methods of transmission and scanning electron microscopy are used to study the evolution of the structure of a welded joint of steels 32G2 and 40KhN in the thermomechanically affected zone (TAZ) under rotary friction welding (RFW). EBSD analysis is used to certify the microstructure in different parts of the TAZ and to calculate the densities of the low- and high-angle boundaries. It is shown that

Parts and billets produced from aluminum alloys and carbon steels using different methods of control, i.e., ultrasonic and radiographic inspection, computer tomography and metallographic analysis, are studied. Computer tomography is shown to be more advantageous than the other methods of nondestructive inspection.

The parameters of the process of production of flawless bimetallic billets from powder steel R6M5 (the external layer) and 5KhNM (the core) are assessed by mathematical simulation. The bimetal has mechanical properties comparable to those of cast and deformed high-speed steel, a more homogeneous structure, and a much lower cost.

The causes of reversible variation of coercivity in alloys for permanent magnets as a result of cyclic heat treatments are analyzed including the effect of magnetostatic interaction between microvolumes on the processes of magnetization reversal and on the magnitude of the reversibility of the coercivity. A scheme of the processes occurring in alloys of the Sm – Co – Cu – Fe – Zr system is suggested

The effect of the chemical composition of the alloys on the magnetic properties of sintered Sm – Co – Fe – Cu – Zr magnets produced with mixing of alloy powders is studied. Elevation of (BH )max of Sm – Co – Fe – Cu – Zr magnets due to increase of the concentration of Fe to 20 wt.% requires observation of a strict proportion of the components and precision choice of the modes of heat treatment. Optimization

Structural and phase transformations at elevated temperatures in α-titanium containing trace nonmetallic impurities are studied by the methods of differential scanning calorimetry and x-ray diffraction analysis. The microstructural and energy characteristics of such transformations are determined.

The possibility of raising the wear resistance and prolonging the service of forging die inserts is analyzed with the aim to elevate the efficiency of the production process and to reduce the cost of forgings. Three sets of inserts fabricated from the same grade of die steel and subjected to the same heat treatment are studied. Additional nitriding (gas or ion plasma one) is applied to two sets for

The effect of the chemical composition and microstructural parameters on the corrosion resistance of low-alloy steels serving in oilfield pipelines is studied. The causes of lowering of the corrosion resistance of the steels are determined. Recommendations are given for raising this characteristic without lowering the strength of the steels.

Results of a study of the fine structure of an alloy of the Mg – Zn – Zr – REE system proving the presence of nanosize plates of self-organizing LPSO-phases after deformation are presented. The Zn and Y hardening elements are redistributed in the periodic rows of the LPSO phases under the effect of the deformation process parameters. The optimum deformation mode of the new alloy provides formation

The effects of the dislocation density and of the concentration of vacancies in the β-solid solution on the processes of aging of intermetallic titanium alloy VTI-4 yielding a Ti2AlNb orthorhombic O-phase are studied. It is shown that the influence of the nonequilibrium concentration of vacancies in the solid solution is decisive for acceleration of the diffusion process and abrupt growth of the sizes

X-ray diffractometry with mathematical processing of the diffraction patterns by the Tikhonov method of regularization, which enhances the resolution, is used to study the phase state in Nd – Fe – Co – B – Zr-base alloys during the reverse reaction of HDDR process at different hydrogen pressures. The range of hydrogen pressures in which the reverse reaction (recombination) of the HDDR process develops

Deformations of straight-sided splines (changes in the width of the hubs) of steels 16MnCr5, AMS6265 and 17CrNiMo7-6 are studied after different treatments, i.e., a hold at 1050°C without carburizing and with slow cooling to room temperature, vacuum carburizing with subsequent slow cooling to room temperature, and vacuum carburizing with subsequent oil quenching. The sizes of the deformations are shown

The effect of long-term thermocycling and mechanical loads on the corrosion resistance of novel nitrogen austenitic Cr – Ni – Mn steels melted under laboratory conditions is studied in various aggressive environments. The steels are subjected to 400 thermal cycles in the temperature range from –100 to 100°C and to cyclic mechanical loading during 1 × 106 cycles. The structure and the mechanical properties

Ametallographic study of advanced low-carbon martensitic steel with high resistance of the supercooled austenite to the transformations by pearlitic and bainitic mechanisms under continuous cooling is performed. The critical temperatures of the transformations occurring under heating and cooling are determined. The kinetics of the isothermal transformation of the austenite in the temperature range

The phenomenon of post-aging retrogression in magnesium alloys containing two rare-earth metals belonging to different groups, i.e., yttrium Y (the yttrium group) and samarium Sm (the cerium group), is investigated. It is shown that retrogression may occur in alloys with different proportions of yttrium and samarium aged at 200°C for maximum hardness and then annealed at somewhat higher temperatures

The structure and magnetic hysteresis properties of nanocrystallized melt-spun ribbons with composition (Sm0.8Zr0.2)(Fe0.72Co0.24Ti0.04)z ( z = 10 – 12) are studied. It is shown that substitution of a part of iron in the composition of the alloy by cobalt raises substantially the Curie temperature but almost halves the coercivity. The decrease is connected with growth in the volume fraction of the

The effect of laser surface alloying with copper on the structure, phase composition and microhardness of surface layers of titanium is studied. Treatment modes improving the structure and special properties of the surface are determined.

A process of hardening of steel 16Kh3NVFMB-Sh involving vacuum carburizing and subsequent hardening heat treatment is studied. It is shown that in order to obtain an optimum phase composition and, as a consequence, high operating properties, the steel should be subjected after carburizing to high tempering for formation of a fine ferrite-carbide structure. The treatment should be finished with quenching

Special features of the process of recrystallization of austenite under hot deformation and its effect on the physical and mechanical properties of rolled sections from bearing and structural steels under the conditions of thermal deformation treatment are studied.

Structural changes occurring in the surface layer as a result of the hardening produced by various variants cyclic loading in high-strength high-quality steel 30KhGSN2A are considered. The sizes of the hardened zone are determined. It is shown that the hardening occurs in the early loading stages and is then followed by a durable state of saturation until failure. The differences in the deformation

Mechanisms of Luders deformation in tensile tests of specimens of steel 08G2B with ultrafine ferrite-bainite structure are studied by the method of digital image correlation. The fields of displacements of εyy and εxy and their distribution over the length of a specimen are determined. Two kinds of Luders deformation differing in the behavior of the Chernov–Luders bands are detected. The results of

The temperatures of phase transformations and the oxidation-reduction reactions occurring under heat treatment of composite Al – Si + flux brazing metal used for brazing of Al alloys and produced by the TRILLIUM™ Technology are determined. It is shown that the melting mechanism is stepped and is accompanied by a chemical reaction between the flux and the oxide film and by diffusion transfer of silicon

The structures and phase compositions of a series of refractory alloys of the Co – Al – Mo – Nb system (the cobalt angle) are studied by differential scanning calorimetry (DSC) and scanning microscopy. The effect of the contents of niobium and molybdenum on the phase composition and the temperature boundaries of the range of existence of the Co3(Al, Mo, Nb) intermetallic phase are determined.

The domain structure and its change as a result of heat treatment of alloys of type Sm(Co, Cu, Fe, Zr)7.5 is simulated with the use of the FMRM software based on the phenomenological approach to analysis of processes of reversal magnetization. Adequacy of the results of the simulation of the domain structure is checked by comparison with published data on experimental studies of similar alloys and

Prospects of oxygen alloying of alloys in the process of deposition of rods on parts from titanium alloys aimed at raising their hardness are considered. Experiments on fabrication of samples of titanium alloys with remelting of filler rods with oxide coating formed by plasma electrolytic oxidation are performed. The main mechanical characteristics of the overlay rod material modified by introduction

Periods of the stage of concentrated strain of specimens of low-carbon steel 08G2B with ultrafine structure are studied by joint analysis of stress–strain curves and fields of digital image correlation (DIC). The DIC data and detection of a through crack on the surface of a tensile specimen are used to justify the use of the parameters of the second period of the stage of concentrated strain as criteria

The possibility of fabrication of powders from alloy 25Kh15KA for synthesizing permanent magnets by the method of selective laser melting is considered. The method is used to make specimens of permanent magnets 10 × 10 × 9 mm size with a density meeting the State Standard for 25Kh15KA magnets produced by the standard metallurgical process to obtain a coercivity of 45.4 kAm, a residual induction of

The integral method is used to simulate the kinetics of growth of γ′-phase layers during nitriding of Armco iron in a microwave discharge chamber. Solution of the system of differential algebraic equations is used to assess the diffusivity of nitrogen in the γ′-phase layers in the temperature range of 773 – 843 K at a surface concentration of nitrogen equal to 5.9 wt.%. The computed activation energy

The main factors responsible for the kinetics of isothermal bainitic transformation in alloy steels are determined using computer simulation of the solid-state phase transformation. The effect of the initial configuration of nuclei of the new phase in the volume of the metal on the parameters of the process of bainitic transformation is determined. Comparative analysis of the computed kinetics of phase