Vol 46, No 10 (2016)

Experimental observations regarding the formation of strengthening surface nanostructures under various external stimuli (electroexplosive alloying, electron-beam treatment, thermomechanical strengthening of rolled strip by fast cooling, and intense mechanical treatment in long-term rail operation) are interpreted on the basis of consistent principles. The formation of nanostructures due to unstable equilibrium states in the surface layers (Kelvin–Helmholtz and Marangoni instabilities) is simulated. The corresponding dispersion equations are analyzed, and analytical formulas are derived for the decrement α as a function of the wavelength λ in the micro and nano ranges. The numerical values of the maxima in the α(λ) curve correspond to the experimental parameters of the nanostructures. A physical interpretation is offered.

Differential heat treatment of rails by air on the basis of the rolling heat is considered. The research is conducted at AO EVRAZ ZSMK during the reconstruction of rail production. The influence of the chemical composition of the steel and the conditions of plastic deformation and heat treatment on the onset of polymorphic transition is studied. Thermokinetic diagrams are plotted for steels of experimental chemical composition. The cooling rate over the cross section of the rail head is investigated as a function of the heat-treatment parameters. The optimal chemical composition and heat-treatment conditions are determined. The heat treatment of rail samples directly after rolling is experimentally studied. Recommendations for the industrial introduction of differential quenching are developed on the basis of the theoretical and laboratory results. Industrial tests show that the rails produced are of high quality and comply with standard requirements.

Simple pump drives with constant-supply pipes are widely used in manufacturing and metallurgy today. Better performance may be obtained by means of transmission–multiplier drives. Such drives are characterized by more uniform load distribution between the pumps, lower working pressure, and hence lower motor power. When two-cylinder drives are employed, the two cylinders must be synchronized. This may be accomplished by employing transmission–multiplier modules in the drive’s control system; the modules operate in transmission mode during the idling pass and in multiplier mode during the working pass. The development of two-speed and three-speed transmission–multiplier pump drives is considered, with modular hydraulic dosing units that operate in transmission mode during the idling pass and in multiplier mode during the working pass.

The oxidation of large octahedral single crystals of magnetite extracted from chlorite shale at Shabrovsk talc mine (Middle Urals) is experimentally studied. Differential heating curves show that the processes occurring in the oxidative roasting of magnetite (Fe₃O₄) are highly reproducible. The mechanism of martensite oxidation is considered, as well as the temperature ranges corresponding to exothermal and endothermal reactions. The thermal effect of martensite oxidation is determined from that of a standard (CaCO₃) and the areas under the differential heating curves on the corresponding thermograms. Those areas are proportional to the thermal effect. The results obtained are of considerable interest: knowing the temperature range of martensite oxidation, the heat sources in the various technological zones of the conveyer roasting machines may be taken into account in establishing the roasting conditions, thereby optimizing the thermal conditions and reducing the fuel consumption.

A mathematical model is proposed for the ignition of sintering batch. The main inputs (control signals, controllable and uncontrollable perturbations) that influence the output variables are identified. The corresponding control problem is formulated. Operational experience with the ignition hearths of sintering machines 10 and 13 at OAO MMK sheds light on the problems encountered in developing ignition-control systems.

Simulation of the primary drive in a cold-rolling mill permits the development of electromagnetic damping of loading and torsional vibrations. Correction of the algorithms for the mill’s automated control systems proves effective here.

The textural anisotropy in thin low-carbon 08ps and DC01 steel sheet is investigated by an electromagnetic–acoustic method. The sensitivity of Lamb waves of symmetric and antisymmetric zero-order modes to change in the elastic modulus of the medium is determined. The relation between the anisotropy of the properties and the mechanical characteristics of the metal sheet is established.