METALLURGICAL TECHNOLOGIES
The article is devoted to the study of powdered raw materials (chromium, its oxide and chloride, boron), micro- and nanopowder of boron and chromium carbonitride and accompanying it pyrolytic boron and carbon with the use of transmission and scanning electron microscopy. It was established that the TEM method in the analysis of powdered raw materials and industrial micron chromium carbide and boride provides complete information acquisition about the shape and size of the particles and their dispersion composition; and the analysis of nanopowders provides visualization of individual particles to determine their linear dimensions, confirming their form close to the spherical ones. The SEM method provides the opportunity to study the tendency of nanoparticles to aggregate, the study of ensemble and individual nanoparticles with the specification of the size range, allows ascertaining the geometrical shape of the particles, proposing and discussing a possible mechanism for the formation of nanoparticles. A distinctive feature of the nano pyrolytic boron and carbon is their ability to form microaggregates of 200 – 400 and 150 – 200 nm, consisting of particles of size from 10 to 40 nm.
The article considers the temperature field modeling issue in «sand and clay form – cast» system. The results obtained during the research allow modeling a thermal process of moulded piece production made both with pure metals and alloys, which solidify in a liquidus – solidus temperature range in dry and wet sand and clay forms with 2 – 14 % moisture.
Ascertained data as to the character of the contact stresses distribution have been obtained thanks to the application of the ascertained solution for the differential equation of longitudinal forces’ balance by the cold rolling. The mentioned solution takes into account the kinematics particularities of a deformation zone. These data have been used to determine the position of the maximum in contact of normal stresses relative to the neutral plane. It has been established that the section of the maximum in contact normal stresses is always situated in the backward slip zone and is substantially behind the neutral plane. This fact corroborates conclusions about the discrepancy of these two sections made earlier by A. Nadai, A.A. Korolyov and A.I. Tselikov. It represents the answer to one of the least studied questions in the up-to-date theory of the thin-sheet (cold) rolling. The qualitative data about the influence of technological parameters of the cold rolling process without tension upon the situation of the maximum for epures of the contact normal stresses relative to the neutral plane have been presented in the paper as well as their analytical treatment.
The article presents the analysis of the forces acting on a coke packing or coal fuel nozzle into the cupola by replacing coke with anthracite and lean coal. The obtained data allow estimating preliminarily in size and shape of burden pieces a probable forecast of cupola melting behavior. The conclusion is that by the transition to the marks of coals to increase the frictional force on the wall of charge, the charge itself must be carefully carve into minimum pieces, which reduces drastically the angle of the engagement and consequently the angle of internal friction coefficient increases as well as the pressure on the side wall of the shaft.
The paper presents experimental studies of the introduction influence of a fl ux-cored wire of PP-H-25H5FMS carbon-fluorine-containing fluoride supplements (metallurgical wastes) and powdered nickel. The introduction of the C-wire system C – Si – Мn – Сr – V – Mo carbon-fluorine-containing additives and nickel can reduce signifi cant-ly the level of contamination of non-metallic oxide inclusions of weld metal, grinding grain; and it also reduces the volume fraction of retained austenite in the weld layer and the formation of small dispersed carbides. The results predict the increase of thermal stability of mill rolls when using the produced wire.
Using the installation of high-metallography, the irregularity of deformation of steel 08Cr18Ni10Ti with the content – 28 % of ferrite has been investigated. It has been established that the average amount of ferrite deformation is greater than the austenite one; and this difference increases with the temperature rise. With the temperature rise increases the slippage on interphase boundaries. The ratio of hot microhardness of δ-ferrite to austenite decreases with the increase of test temperature.
A comparative analysis of existing combined blowing technologies of metal in converters has been performed, as well as shortcomings of the considered technological options have been revealed. The researchers offer a new technology of combined blowing of a converter bath with the supply into a workspace unit different pulse jets of oxygen and indifferent gas through the upper bunk lance and indifferent gas through the bottom blowing of devices.
ENGINEERING IN FERROUS METALLURGY
The article describes the vibrational impact arising due to the presence of gaps in bearings, as well as the affect on the reliability of the roll crushers. The design of the elastic pneumatic device for sampling gaps in bearings when working roll crushers is described and the reduction of vibration level by eliminating the gaps is proved experimentally.
MATERIAL SCIENCE AND NANOTECHNOLOGIES
The paper deals with the microhardness of TiN – TiNi composite obtained by iron-plasma deposition of titanium nitride on the TiNi alloy surface. The possibility to determine analytically the microhardness of thin surface layers according to the method of a restored print has been shown. The microhardness of the protective layer obtained by the proposed deposition regime is close to the base microhardness that meets the requirements for the TiNi-based items for medical applications.
The processes of structurization in the contact region of almost insoluble metals (Cu – Pb, Fe – Cu) under various conditions of plastic deformation were investigated. It was established that during the process of interaction of solid-phase samples of lead and copper, iron and copper, subjected to volume compression, the products of mechano-chemical reaction may be formed. They have a structure which is different from the structure of the original components. In the case of the interaction of copper cumulative jet with a steel rod substitutional solid solutions were formed. The new phase was obtained as a result of passage of mechano-chemical reactions. It is shown that a variety of models of structure formation in gradient conditions can be combined within the structural models of selforganization in the waves of plastic deformation.
SHORT REPORTS
ISSN 2410-2091 (Online)