Volume 61, Nº 9-10 (2018)

A piercing process for a new four-high screw rolling mill without guides designed by comparing existing piercing processes in screw rolling mills is proposed. To evaluate the feasibility of this process, piercing in two-, three-, and four-high screw-rolling mills was simulated using QForm FEM software. Simulation results demonstrate advantages of the new piercing process according to several criteria, including energy consumption.

Procedures for calculating heat losses and temperature are adapted to air tuyeres of blast furnaces. The effect of the thickness and thermal conductivity of the insulation liner on the inner wall of an air tuyere and the air gap between them on the heat losses through the inner wall and the temperatures of the liner and inner wall is analyzed using an Excel linear code. It is shown that the air gap between the liner and the inner wall has a strong effect on the heat losses through the inner wall and its temperature.

The structure and mechanical properties of a number of experimental 12% chromium steels of the ferritic-martensitic class are studied, whose prototypes are two domestic heat-resistant steels EP-450 (12Kh12М2BFR) and EP-823 (16Kh12МVSFBR). The possibility is demonstrated of using isothermal hardening for controlling the quantitative ratio of martensite and ferrite in test steel structure, characterized by considerable austenite thermal stability. It is established that ferrite content in the original steel structure has a specific unfavorable effect on high-temperature strength.

An improvement in resistance to overall and local corrosion in neutral aqueous media with hydrogen index pH 6–8 is important for numerous structures operating under atmospheric conditions, in sea water, for heating network pipelines, oil industry pipelines (oil pipelines and water conduits), and many other forms of structure and equipment. Under these conditions, corrosion proceeds by a classical electrochemical mechanism. Today, there is no single point of view for the optimum chemical composition and microstructure for steels for simultaneous provision of good corrosion resistance in aqueous media and satisfactory mechanical properties. In this work, the effect of chemical composition and microstructure parameters on corrosion resistance of carbon and low-alloy steels of strength classes K52–K60 in aqueous media is studied with the aim of developing specifications for these properties in order to increase the operating life of steel equipment, in particular oil industry pipelines.

Production is achieved for the first time under Electrostal Metallurgical Plant conditions for rolled bars of nickel superalloy grade VZh172. During assimilation, various heat and deformation regimes were checked for metal in rolling mill 350/250 with the aim of finding the optimum technology making it possible to prepare metal product of the quality required.

The results of experimental and theoretical studies on the technology of rolling tramrails in continuous reversing tandem train of stands of a universal rail and structural steel rolling mill are presented. Best-performance speed charts for the main drives of the rolling stands are drawn. A new approach to high-speed rolling schedules for rolling grooved tramrails in a universal continuous three-stand train is proposed.

Technology is developed for preparing semifinished sheet of hypereutectic alloys based on the aluminumcerium system intended for operation under conditions of x-radiation. The technology is based on creating a test alloy by casting and subsequent deformation treatment. Two versions of cast billet preparation are considered in the work. Sheet material prepared by rolling these billets exhibits good adaptability and may be used for producing engineering objects.

Results are given for physical modeling of hot rolling of alloy with reduced density of the Al–Mg–Li–Zr–Zn–Sc system (1424) in the temperature range 420–480° and deformation rate 1–40 sec^–1. It is established that with a constant strain rate deformation stresses decrease with an increase in test temperature. An increase in strain rate leads to an increase in deformation stress at constant temperature. As a result of dynamic recovery and dynamic recrystallization, there is partial weakening of specimens accompanied by a reduction if deformation stress. Constants are determined for a rheological model of hot deformation, increase the Zener–Hollomon parameter and the rule of a hyperbolic sine: α = 0.023 MPа^–1, n = 1.96, Q = 101.04 kJ/mole, А = 1.22·10⁶ sec^–1. It is shown that alloying with scandium reduces activation energy which leads to weak strain hardening and this means it provides good alloy 1424 production properties.

The finite-element model and the results of simulation of the continuous plastic forming process of producing welded pipes of small and medium diameters in TESA electric pipe welding line are described. It is shown that the roll forming process is characterized by a nonuniform stress–strain state (SSS) of the metal throughout the entire process. Experimental results on residual stresses in welded pipes before and after welding and sizing, which validate the results of the mathematical simulation, are presented. To reduce the residual stresses and the nonuniformity of the SSS of a hollow workpiece, it is recommended to use intensive reversed deformation.

The results of roller briquetting of coke breeze with different binders (liquid glass and lime) are presented. The dependence of the density and drop strength of a briquette on the precompaction pressure in the deformation zone is established. The nonuniformity of the density distribution over the briquette cross-section is determined.

The effect of cooling regime after rolling and also subsequent spheroidizing annealing are studied for rolled product of special alloy steel 40Kh of an industrial melt on metal structural state and amount of relative reduction of area. It is established that the amount of reduction of area, varying uniformly round rolled product capacity for cold upsetting, increases with a reduction in the proportion of ferrite and an increase in steel ferrite-pearlite structure uniformity and fineness. The most favorable microstructure and high value for reduction of area occur after spheroidizing annealing of rolled product with a bainitic structure.

Data on the production of blanks for gas-turbine engines and power units in the 200 MN die-forging press at the Electrostal Metallurgical Plant are presented. The range of geometries and grades of blanks produced in the 200 MN press is described.

It is shown that one area for development of the internal market for aluminum is formation of a branch (geographical) structure for processing it, including use of recycling scrap accumulated within a region based on newly created production with a broad range of finished product output. Under conditions of a typical regional producer ALTEK dynamics of forming the level of mechanical properties within the scope of a round cast workpiece manufacture – extrusion – heat treatment production system are studied. It is shown that the indices achieved are adequate for fulfilling the requirements of the majority of users. At the same time, further development of the production cycle is possible by creating a complete operational control system for both semiproduct and finished product quality.

Comprehensive processing of ore and technogenic raw material containing zinc and lead requires improvement of lead-containing product quality provided by zinc industry enterprises for lead extraction by a pyrometallurgical method. Research and development are conducted for Waelz-oxide pyrometallurgical treatment technology with preparation of carbonized lead cake containing more than 45% lead, not more than 5% sulfur, and with a moisture content after filtration less than 35% suitable for black lead preparation in short-drum kilns with good technical and economic efficiency. Carbonization and pyrometallurgical treatment of carbonized lead cake make it possible to reduce soda consumption and sulfur compound concentration considerably in waste gases. Introduction of contemporary technology for preparing Waelzprocess charges drawing on treatment of copper production zinc- and lead-containing dust, and also optimizing process parameters for cake preparation and carbonizing make it possible to increase the lead content in carbonized cake from 40–43 to 46–50%. In order to resolve the problem of increasing lead content and reducing lead cake moisture content, filtered in filter-presses, research is conducted in the course of which the phase composition of sulfate and carbonized products and thermal effects proceeding during carbonized cake drying and heating are studied. Optimum parameters are determined for introducing the technology on the bases of industrial tests. Washing lead sulfate cake before carbonization makes it possible to increase the lead content by 2–4% in carbonized cake. A reduction in pH during lead cake carbonization from 8.5–9.0 to 7.0–7.5 makes it possible to reduce the filtered product moisture content from 35–36 to 27–30%.

A polymer coating is often used instead of lubricant in order to protect the threaded part of an oil pipe fitting. There are several forms of these coatings of different composition applied by spraying to the threaded element of a pipe. Metal surface preparation before coating application has a considerable effect on polymer coating quality. Conversion coatings that formed on a pipe threaded surface and couplings as an intermediate layer between a metal surface and a polymer coatings are analyzed. The conversion coatings selected are various phosphate coatings and an alternative phosphate-free zirconium coating. Comparative study of these coatings includes an analysis of application technology, a study of conversion coatings physicochemical properties, and comparative tests for a conversion coating – thread lubricant coating system.

The first devices for preparing workpieces (bars) of refractory metal powders (tungsten and molybdenum) in the form of dismountable steel dies installed in a hydraulic press of special construction with vertical and horizontal cylinders were developed by the American firm General Electric in 1909. This article considers known and new die and device constructions for molding bars from refractory metal powders developed by scientists of Ural scientific schools.

The Acknowledgment at the end of the paper should read: Financial support from the National Natural Science Foundation of China (NSFC) (No. 170410656) and the Collaborative Innovation Center of Nonferrous Metals, Henan Province (15A450001) is gratefully acknowledged.