Russian Metallurgy (Metally)最新文献

Despite restrictive measures against Russian business, there remains a tendency to increase the volume of collection and consumption of scrap metal in the Russian Federation and most developed countries of the world. The revealed processes associated with the collection and consumption of scrap metal in Russia in 2011–2021 confirmed the positive prospects for the development of an independent resource industry for metallurgy in the medium term. This trend necessitated digital modernization of the existing domestic scrap collection–scrap consumption accounting system using a blockchain technology with automatic generation of a QR code for each batch of scrap metal. The architecture of a system with the main functional blocks of a digital platform is presented, and a scheme for administering data on the movement of scrap metal batches in a system with a QR code generator is developed. As a result, the document flow and the administrative costs for tracking the movement of material and cash in complex supply chains of goods and services are significantly reduced. In addition, the performance of control functions by managers of companies and various fiscal authorities participating in the resource business process is substantially facilitated.

Abstract—The influence of the initial orientation of a two-radius roller on the stress–strain state during surface plastic deformation (SPD) is considered. The finite-element method and the ANSYS computer program are used to determine the values of the temporary and residual stresses and deformations of cylindrical parts for different initial orientations of a two-radius roller during SPD. It has been established that the scheme of reversible rotation of a two-radius roller positioned at an angle of 45° relative to the feed direction has the greatest effect on the stress–strain state at the deformation location, while hardening with a two-radius roller, whose axis of rotation is perpendicular to the feed direction, has the minimum effect.

Since modern gas turbine engines operate under changing temperature load conditions, one of the important characteristics of the protective coatings on turbine blades is their high resistance to the appearance and development of cracks under mechanical and thermal loads. The effective internal heat removal systems used to cool turbine blades lead to an increase in their thermal stress. Currently, the cracks induced by thermal fatigue are one of the common defects in the protective coatings on turbine blades. The heat resistance of the coatings at high temperatures is determined by the following three factors: the shape of the part onto which a coating is applied, the coating thickness, and the phase composition of the surface layers or the maximum aluminum content in the coating. Therefore, when a protective coating is chosen under specific operating conditions, it is important to know the influence of these factors on the heat resistance of the coating. In this work, we compare various coatings in terms of their resistance to cracking during cyclic temperature changes. The dependence of the heat resistance of the coatings on the method of their application and the phase-structural state is established. The revealed mechanism of thermal-fatigue crack formation and propagation as a function of the phase composition of the initial coating is especially valuable. The life of the protective coatings under cyclic temperature changes is shown to depend on the chemical composition of the coating and the method of its formation. The dependence of formation of thermal-fatigue cracks on samples with the coatings under study on the number of temperature change cycles is found.

Abstract—A computational and experimental estimation of the thickness of coating formed by electrocontact welding of a metal woven mesh onto bronze parts is carried out. The calculated coating thickness of the metal woven mesh is shown to correlate quite well with the coating thickness experimentally formed at the optimum electrocontact welding parameters.

An enhanced-performance composite antifriction material was created based on iron-containing material. Features of the structure formation of glass–metal composite materials produced from carbonyl iron powder by powder metallurgy methods were considered. The relationship between the method of fabricating the material and the features of its microstructure was investigated, and so was the relationship between the composition and structure of the resulting composite materials and their properties. The obtained samples were examined by microstructural analysis with a VEGA 3 TESCAN SEM microscope.

Sealing assemblies and welded rings made of nickel superalloys for sealing the gas–air path of the stator in a gas turbine engine are developed. Samples of sealing assemblies and cross-sectional profiles of U- and W-shaped sealing rings made of KhN50VMTYuB alloy tapes are demonstrated. Key quality requirements for sealing elements are formulated.

Abstract—Data on the effect of the annealing temperature on the microstructure of a prepared diffusion coating are reported. The minimum annealing temperature for the formation of a diffusion coating is determined. Results of electron microprobe analysis of the chemical composition and microstructure of the prepared coatings are reported; the changes in the microhardness of them are also considered.

The deformation behavior of cast super duplex steel is studied in the temperature range 1100–1250°C and the strain rate range 0.1–10 s^–1. Hot deformation is performed by uniaxial compression of cylindrical specimens on a Gleeble 3800 simulator of thermomechanical processes. The flow stresses are shown to decrease with increasing temperature and decreasing strain rate in accordance with a change in the Zener–Hollomon parameter of the temperature–rate deformation conditions. The shape of the flow curves indicates that hot deformation is accompanied by intense dynamic softening, as a result of which the flow stresses decrease or remain unchanged after reaching peak values. Under all hot deformation conditions, ferrite acquires a dynamically recrystallized structure. At the lowest deformation temperature (1100°C) and relatively high strain rates (1–10 s^–1), the mechanism of austenite softening is dynamic recovery. A decrease in the strain rate or an increase in the deformation temperature causes partial dynamic recrystallization of austenite. Under similar deformation conditions, the plastic flow stress of the steel under study is significantly higher than that in standard duplex stainless steels. When analyzing the peak flow stresses, we determined the effective hot deformation activation energy (Q = 501.31 kJ/mol) required for calculating the Zener–Hollomon parameter. An expression for describing the peak flow stress is obtained in the form of a hyperbolic function of the Zener–Hollomon parameter. This expression describes the experimental data array with a high accuracy and can be used to estimate the required energy–force parameters of forging and rolling equipment. A comparative estimation of the hot ductility of the super duplex steel is performed by finding the strain corresponding to the appearance of the first macrocracks on the specimen surface. At a strain rate of 10 s^–1 (which is characteristic of hot forging processes), the safest deformation temperature range of the steel is shown to be 1150–1250°C, in which austenite undergoes partial dynamic recrystallization reducing the risks of cracking.

A technology for producing a Ti–26Nb alloy is developed. The effect of heat treatment conditions on the structure and the phase and chemical compositions of ingots is studied. Optimum homogenizing annealing conditions (900°C, 12 h) are found, which leads to the formation of a completely recrystallized structure. After melting, the alloy is found to be represented by a mixture of 66.5 vol % β_m-Ti and 33.5 vol % α'-Ti with the bcc and orthorhombic crystal lattices, respectively. After annealing, the phase composition is shown to change to the continuous β phase with traces of the ω phase, which increases the microhardness of the alloy. After annealing, a homogeneous distribution of chemical elements over the entire volume is observed. The oxygen, nitrogen, carbon, and sulfur contents correspond to standard specifications for titanium alloys.

The influence of the type (grits from an ingot, a quick-cooled plate) and size of the fraction of a modifier and the REM content on the structural of camshaft castings made of ChVG40 vermicular graphite iron (VGI) are studied.