Russian Metallurgy (Metally)最新文献

Abstract

The results of developing a (Co–Cr–Si) + (Cr–Al) diffusion coating using a two-stage powder method are presented. The mechanisms of transfer of cobalt, chromium, silicon, and aluminum atoms to the surface of a ZhS6U superalloy at the first and second stages of processing are discussed. The characteristics of the composition, structure, and life of the (Co–Cr–Si) + (Cr–Al) coating are determined at a temperature of 900°C under corrosion conditions in the presence of an aggressive salt deposit.

Abstract—

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.

Abstract

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.

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.

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.

Abstract

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—The paper presents the results of a finite element study of the influence of friction conditions at the tool–metal contact surface on the stress–strain state of the metal in the deformation zone in cold forging of bars on a lever radial forging machine. The thus-obtained data were analyzed to give recommendations on the magnitudes of friction forces at the tool–metal contact surface in forging in order to provide rational forging protocols.

Abstract

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—This paper presents experimental results on the machining of parts fabricated from powder materials. The specifics of porous surface structure formation in powder-metallurgy parts upon abrasive finishing are described.