Vol 46, No 1 (2016)

Work by researchers at the Russian Academy of Sciences on new materials (metals and ceramics) and new technologies is reviewed. The topics include new high-strength corrosion-resistant nitrogen steels; high-temperature light alloys and composites based on intermetallics; modifiers for wheel steels; complex ferroalloys containing V, Cr, and Ni; anticorrosive protective coatings based on ultrafine Zn powders; catalytic converters for vehicle exhaust gases; magnetically hard materials with high temperature–time stability and excellent mechanical characteristics; nanostructured stents for endovascular operations; and corrosionand wear-resistant coatings and corresponding methods of plasma application. Methods have been developed for longitudinal rolling with shear deformation to improve the properties of the rolled product; recycling of oily scale; monitoring of the wear of the refractory lining at any point of the blast-furnace hearth; and monitoring of the content of inclusions in rail steel. Technologies have been developed for special electroproduction of steel for the power industry; synthesis of massive monocrystalline samples of transition-metal nitrides and nanopowders of W, Pt, and Ti and their carbides and nitrides; the processing of leucoxene concentrates from the Yareg Basin; the production of titanium implants with porous coatings; ferrous and nonferrous metal shot and powder; ultrafine Zn powder; recycling of metallurgical wastes with the extraction of Zn, Sb, Sn, and Fe; the production of sintered nanocrystalline Ta powder for capacitors; the processing of molybdenum-bearing sulfide material to obtain rare-earth metals, MoO₃, and CaMoO₄; and the utilization of sulfur dioxide. Injection units and technologies for their use have been developed, as well as high-speed systems for the plasma application of metals on surfaces including paint coatings, plastics, and cardboard. Data have been obtained regarding the thermodynamic functions of the solution of oxygen in Fe-based melts and the reactions of elements dissolved in such melts (Cr, Mn, Nb, V, Si, B, C, Ti, Zr, Al) with oxygen.

Control of a vacuum arc furnace by means of a programmed step in the melting process is described. A model of voltage control in a vacuum arc furnace was considered in [1, 2]. However, the control algorithm is associated with considerable static error. The error may be reduced using a programmed step, corresponding to previously calculated motion of the consumable electrode so as to maintain constant melting rate and a specified range of the electrode gap. By this means, blind control of melting in the vacuum arc furnace, without any feedback, is possible for ideal electrodes. In the case of nonideal (real) electrodes, however, such blind control cannot maintain the required melting parameters. Therefore, in that case, voltage feedback must be employed. Matlab software is used for simulation of the process in the case of ideal and nonideal consumable electrodes.

A mathematical model is developed for the stress state of a casting when a cavity is formed by a cylindrical rod. Formulas for the radial and azimuthal stresses and also the contact-force distribution permit prediction of the forces between the casting and the rod, with different rigidities expressed by the longitudinal elastic modulus. The stress is found to be greatest in layers of the casting in contact with the rod surface. The dependence of the radial and azimuthal stresses in the casting and the distributed contact force on various factors—the temperature gradient, the rigidity of the casting and the sand–clay casting mixture, and the geometric parameters of the casting (the wall thickness and external radius)—is considered. The influence of these factors on the stress–strain state of the casting wall—specifically, the equivalent stress obtained by means of the second strength hypothesis—is assessed.

Improvement in pipe production on a longitudinal rolling mill is proposed. The tandem longitudinal pipe rolling mill in the pipe-mill aggregate (PMA)-140 at PJSC (public joint-stock company) Sinarsky Pipe Works is considered. Currently, pipe is produced both from rolled billet (diameter 120 mm) and from continuous-cast billet. To reduce costs, it would make sense to discontinue the use of rolled billet and to produce all of the pipe from continuous-cast billet in the existing PMA-140. In order to employ continuous-cast billet, more profound reduction in the tandem mill is necessary. At present, the reduction is 1.16–1.5 in longitudinal rolling mill 1 and 1.07–1.15 in longitudinal rolling mill 2. With greater reduction, longitudinal guide marks may appear on the pipe surface. A possible approach to decreasing the pipe wall thickening in the groove taper and hence reducing the rejection rate due to longitudinal guide marks is to employ kinematic tension in rolling an oval sleeve on a short mandrel. The influence of the kinematic tension on the pipe shaping in grooves during longitudinal rolling of an oval sleeve is investigated. This method is found to diminish the thickening of the sleeve wall in the groove taper in longitudinal rolling mill 1. That lowers the likelihood of longitudinal guide marks on the pipe’s internal surface. The possibility of increasing the reduction in rolling on an automatic tandem mill is confirmed.

In the sintering shop at OAO Ural’skaya Stal’, industrial trials are conducted with a view to improving the pelletization by wetting the sintering batch with water-soluble organic surfactants. The use of surfactants improves the granulometric composition of the batch, its gas permeability, and hence the sintering efficiency. The use of surfactant is most effective with optimal wetting of the batch (7–8%), with consumption of the experimental binder at a rate of 1.2–1.6 L/h. (The surfactant concentration in aqueous solution is 0.3⎯0.4 mL/L.)

Current geometric requirements on pipe—especially thin-walled pipe for gas pipelines—set strict limits on the deviation of the cross section in shaping. A special control algorithm for the drives in the sheetbending machine minimizes local geometric errors in the cross section during the roller shaping of largediameter pipe from strip. Analysis of the nonuniformity in deformation permits the formulation of a cyclic operating sequence for the drives. Experiments confirm its effectiveness. On the basis of this research, automatic control of the drives in the sheet-bending machine is possible.

To meet the demands of the auto industry, facilitate import substitution, and improve the global competitiveness of Russian products, there is a pressing need for new high-quality economical steels with excellent stamping properties, strength, and corrosion resistance. Between 2001 and 2011, intensive research permitted the development of high-technology production processes for a new generation of automotive steels; these technologies have no counterparts around the world. A fundamentally new approach was adopted: the required structure and properties of the metal are obtained by regulating the deposition of nonmetallic excess phases, the state of the solid solution, the grain boundaries, and the types of impurities at all stages of production. On the basis of extensive research, including more than 1000 trial melts, production technologies for more than 30 grades of automotive steel that match—and in many respects outperform— their foreign counterparts have been introduced at OAO MMK and OAO Severstal’.