Том 2016, № 13 (2016)

The density and the ultimate tensile strength of steel are studied during melting, secondary refining, and continuous casting in an arc-furnace shop.

The studies directed on designing an advanced rhenium-free nickel superalloy, which is an analog of ZhS32VI alloy, are performed. The chemical composition of the alloy has been found and an experimental alloy batch has been melted (10 kg). Microstructural and metallographic studies and strength tests are carried out. The new single-crystal superalloy has a long-term strength σ¹⁰⁰⁰₁₀₀= 238–248 MPa at a density of 8.87 g/cm³.

The mechanism of formation of boron-containing phases during steel borating has been studied. The transformations in the boride phase are shown to be related to the decomposition and appearance of new clusters, i.e., their synthesis owing to the coalescence of defects. This is related to the probability for boron or iron vacancies to be formed and fluctuated. A mathematical description of the kinetics of boride layer formation is given.

The interaction of oxidation atmospheres with metals and alloys and the influence of an oxide film on the formation of a hardened layer upon the subsequent nitriding are considered.

The depths to which plastic deformation occurs under ball indentation of a steel plate at various loads is determined. It is established that the ratio of the depth that plastic deformation reaches to the indentation depth is constant (approximately 15) independently of the indentation load. This finding allows us to conclude that this ratio should be held no less than 15 in hardness measurements. Experiments demonstrate that the lower the hardness of the metal substrate, the larger the decrease in the measured hardness when the ratio is lower than 15.

The addition of nanodispersed powders to the area of welded joint is a promising control mechanism of controlling the properties of the weld metal. This article is aimed at determining the influence of TiN, TiCN, and WC nanoparticles (<100 nm) on the structure and the properties of the welded joint.

The cooling of the products of self-propagating high-temperature synthesis in a heat-generating reactor, which is used to synthesize refractory compound powders, is considered.

The physicomechanical properties of galvanic chromium coatings on steel parts are studied. Mechanical treatment of a base and a coating by various finishing methods is shown to change the physicomechanical properties of the coatings.

The SiO₂–TiO₂ aerogel composites used in the heat insulation of a hydrothermal reactor and the method of their fabrication using a liquid glass technology are analyzed. The process of fabrication of the composite material includes the following stages: the ion exchange of sodium liquid glass with the formation of silica hydrosol; the concentration of hydrosol; the formation of hydrogel and its maturing; the formation of alcogel of an SiO₂–TiO₂ composite material; surface modification; subcritical drying of alcogel with the formation of SiO₂–TiO₂ composite ambigel; and its heat treatment, granulation, and classification. The influence of infrared absorber (titanium dioxide) and the temperature of heat treatment of an SiO₂–TiO₂ aerogel composite material on its structural and thermal characteristics is studied.

The machining of parts made of powder materials by densified dispersed abrasive media is experimentally studied. The role of lubricant-cooling agents in polishing and their influence on the efficiency and quality of machining is considered.

The effect of severe plastic deformation on the copper density during forming parts using cold rotary drawing is considered. The consideration is performed as applied to technology of manufacturing of cumulative coatings of commercially pure oxygen-free copper. The copper density behaves nonmonotonically during severe plastic deformation. The results can be useful in theoretical and applied studies of the consequences of significant plastic deformations appeared in metal forming technologies.

A pseudo-α PT3V titanium alloy with a grain size of about 10 μm is shown to demonstrate all evidence of superplasticity in the temperature range 880–920°C during tensile deformation at a strain rate of 10^–3–10^–2 s^–1: the relative elongation is higher than 300% and the strain-hardening exponent is higher than 0.4. It is concluded that the use of isothermal stamping of bottom-type parts from the titanium alloy in the superplastic state is profitable.

The energy–force parameters of free rolling of a strip without its tension and rolling with one backward or forward creep zone in the deformation zone are compared. The limiting backward or forward tensions are determined, and the change in the linear sizes of a composite billet during deformation in a rolling mill is considered.

The hardness of a metal and the near-weld zone is studied for traditional contact spot welding and an adhesive–weld technology using various adhesive materials.

A method is considered to reach the air-tightness of the flange joint of the casing of an impeller pump with its cover using an anaerobic sealant instead of a gasket made of a thermoplastic material. The possible causes of leakage of working fluids that are related to the errors of machining flange surfaces and the specific features of their assembly are shown. The properties of anaerobic sealants that ensure the air-tightness of the flange joints are presented.

A technique is developed to determine the homogeneity of the structure in a surface layer subjected to strain hardening. Static pulsed treatment is found to be one of the most effective surface plastic deformation methods that can be used to control the uniformity of hardening a surface layer. This treatment makes it possible to create a hardened surface layer to a depth of 10 mm with a homogeneous or heterogeneous structure.

The existing handheld and portable hardness testers are classified depending on their operating principles. The advantages and disadvantages of the measurement procedures and the hardness testers are considered. The hardnesses of the metal parts with different masses and stiffness are measured by mechanical and physical-mechanical hardness testers and compared. The test errors are estimated. Recommendations for the calibration of the hardness testers of physical and mechanical operating principles are given.