Том 46, № 4 (2016)

The capture conditions for an H-beam blank by the grooved rollers in the 1300 reduction stand of a universal beam mill at Nizhny Tagil metallurgical works are considered. The stress–strain state of the metal in the deformation regions on rolling the beam in the roller grooves of the reduction stand is investigated. The calculation results are presented as the distribution of the contact normal and tangential stress in the deformation regions as the H-beam blank is captured by the rollers. The normal tensile stress in the wall of the Hbeam blank is no more than 52 MPa. In the deformation regions of the crosspieces and at their junction with the wall, the normal contact stress is compressive. That indicates a stress state favorable in terms of H-beam quality, with high compressive stress. A method is developed for calculating the dynamic loads in the drive line of the 1300 reduction stand, with allowance for the gaps in the spindle joints.

Terra thermodynamic-modeling software is used to investigate the solid-phase reduction of iron, in two stages: (1) reduction in an elementary model system; (2) reduction of iron from ore by coal. In the first stage, analysis of the redox conditions in the Fe–C–O system permits determination of the boundaries of the reductive, transition, and oxidative regions and the corresponding values of the oxygen/carbon ratio. Analysis of the reducing properties of coal by calculating the equilibrium compositions in the range 373–1873 K on the basis of Terra software shows that, within that range, the gas composition is practically the same for all the types of coal considered; only the content of volatiles is different. Sharp increase in gas volume begins at 673 K and ends at 1073 K. In the second stage, thermodynamic modeling permits the determination of the optimal consumption of poorly clinkering SS coal, long-flame D coal, and 2B lignite for complete reduction of iron from ore of specified composition.

The residual stress due to welding in steel and alloy structures is analyzed. The greatest residual stress is produced by cooling of the welded structure. The results of calculations are in satisfactory agreement with the experimental deformation of the structure in welding on a test bench. The tests reveal the direction of the internal stress and permit assessment of the geometry of parts on the basis of a model of the temperature fields in the butt welding of steel and titanium-alloy workpieces. A coercimeter may be used to assess the stress state of the material and its defect content. By that means, it is possible to predict the structural state and properties of weld joints. The dynamics of welding deformation may be understood on the basis of the internal residual stress and the structural transformations produced by the welding process.

To obtain a nanocrystalline structural state of materials based on aluminum and titanium, high degrees of deformation are employed: rolling with considerable reduction; and shear under high pressure (5 GPa). The nanocrystalline materials obtained are used to create thin-layer composites, with nanocrystalline silicon between the uniform layers. Measurements show that the microhardness of the composites after the application of high pressure is 2.5 (for Al–Si) and 6 (for Ti–Si) times that of the initial material, while optimal practical properties are retained. The nanocrystalline composites obtained may be recommended for ultrahard thin-layer coatings on narrow or stressed local sections of components and for local corrosion protection.

Mathieu–Hill equations are used to describe the parametric vibration of the connecting rod in the primary drive of a cold-rolling mill for pipe production. The Eins–Strett diagram is presented, and regions of stable connecting-rod operation are identified. Connecting-rod designs are proposed (on the basis of highstrength alloys), and the crank of the primary drive is modernized (with splitting of the crank gears). That stabilizes pipe production.

The influence of continuous casting of steel on the high-temperature plasticity of microalloyed steel is investigated. The Gleeble-3800 system is used for the physical modeling of the steel’s hot plasticity. The temperature ranges of plasticity are determined in different conditions of slab cooling in the continuouscasting machine. In all the simulations, a trough is seen on the temperature dependence of the steel’s plasticity. With enlargement of the grain boundaries (decrease in grain size), the high-temperature plasticity increases.

On the basis of experience at numerous modernized steel plants between 2006 and 2015, proposals have been developed for the reconstruction of the gas cooling and cleaning ducts for (350–400)-t converters, as an alternative to the system employed by Primetals Technologies Austria (previously Siemens Voest Alpine). The basic equipment employed in the reconstruction may be manufactured at Russian plants, and its introduction requires minimal reconfiguration of the metal structures in the existing converter shop.