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This article presents the data on the study of the influence of the elongation coefficient during piercing in a two-roll screw rolling mill with a cup-shaped arrangement of rolls and guide strips on the accuracy of the pipes obtained. It is shown that high degrees of deformation and intermediate heating negatively affect the wall thickness variation of the pipes. [ABSTRACT FROM AUTHOR]

The joint influence of degree and strain rate for copper and low-carbon steel is considered. A formula for calculating the average strain resistance during rolling with the joint effect of strain rate and cold-hardening is proposed. It is shown that calculating the average deformation resistance in the compression zone with joint consideration of work hardening and strain rate is more accurate. [ABSTRACT FROM AUTHOR]

Experimental results of melting and in-laboratory rolling of steel of K55 grade strength of new chemical composition with 0.32% C, 1.1% Mn and with addition of vanadium are presented. The phase transition kinetics of melting of new chemical composition by method of building the thermokinetic diagram of transformation of deformed austenite at continuous cooling is explored. Based on the analysis of the constructed thermokinetic diagram, the recommendations for obtaining the target ferrite-perlite microstructure at mill 2000 of PJSC "Severstal" are given: cooling rate up to 20°C/s at a coiling temperature above 580°C. The microstructure was studied by optical microscopy and scanning electron microscopy. All samples had a ferrite-pearlite microstructure. The mechanical properties of the experimental rolled strips after correcting the cooling modes meet the target requirements for K55 steel: σY = 379–552 N/mm2, σUTS ≥ 655 N/mm2, δ5 = 22%, KV+21 ≥ 27 J. [ABSTRACT FROM AUTHOR]

The numerical analysis methods of the thermal state of mandrel bars in a three-high rolling mill are developed using modern computer software. The initial and boundary conditions are determined based on the special features of the rolling process in a three-high mandrel screw-rolling mill. A qualitative assessment of the thermal state of a mandrel bar is conducted, and its significant heterogeneity is revealed through a graphical representation. The effect of the rolling temperature and the diameter of the mandrel bar is found. Small-diameter mandrels are heated to higher temperatures (577°C) at a significantly lower gradient between the axial zone and the surface. The increase in the mandrel diameter to 154 mm reduces the outside surface temperature to 530°C and increases the temperature gradient in the near-surface layers to 18°C/mm. The temperature in the near-surface layers for the 154-mm-diameter mandrel at a distance of 10–15 mm from the surface decreases from 530 to 315°C. The special features of the temperature field in the cross section are determined in consideration of the thermal interaction between the shell and the mandrel bar in contact with the hot metal and in the roll gaps. The temperature of the near-surface layers in the contact area is 30°C higher than in the gaps. The temperature dependences of the characteristic points in the cross section on the rolling time are determined. The intensive growth is found to occur in the first two seconds according to the parabolic law, and then according to the linear law. The temperature of the central layers with a radius of 50 mm increases with a significantly lower rate by about 100°C for all rolling period, while the near-surface layers are heated by 300–400°C for the same period. [ABSTRACT FROM AUTHOR]

Abstract—Engineering solutions in pipe production are considered upon the development of tribological principles for reducing friction forces at the contacting surfaces in order to improve the quality of the resulting product. An experience in testing engineering solutions under industrial conditions with assessing economic effect resulting from their application in the manufacturing of pipes is presented. It is shown that achieving a high product quality at minimal cost with no use of modern lubricants is impossible. [ABSTRACT FROM AUTHOR]

Investigation of the forming of continuous cast billet (CCB) possessing a rhomboidity defect was initiated just recently and were related to the extensive incorporation of capacities for the fabrication of sectional CCB and expansion of the grooveless rolling technology (GR) in the roughing mill groups of continuous section mills. The results of integrated study on evaluation of the change of contact conditions in the box pass of breakdown mill upon forming of the CCB possessing the rhomboidity defect are given. Processing of the experimental data using the suggested criterion Ktorsion, which considers the ratio of individual elements of the contact area in contrast to existing criteria, showed that an increase in the rhomboidity value of the blank in the range under study results in rearrangement of contact areas along the groove. Change of the fixation degree of the billet in pass a = Bb/Bp on the whole stabilizes the rolling process in the box pass. The stabilization mechanism of the rolling process is based on the fact that the contact area increases with an increase in the degree of fixation on the second edge and, consequently, the compensating torque arises. Thus, large degrees of metal fixation in the box pass for the rolling conditions of CCB possessing a rhomboidity defect are recommended. [ABSTRACT FROM AUTHOR]

Production of seamless pipes made from 08-12Cr18Ni10Ti austenitic stainless steel is developed in cooperation of JSC VTZ and JSC RusNITI involved in the PJSC TMK. Development was preceded by the complex of investigations on the technology base of PJSC TMK in JSC RusNITI. This paper shows the study results of longitudinal rolling of pipes using physical and computer modeling. Adaptation of the study results and test pipe rolling were realized at the manufacturing area of JSC VTZ in a PRM 159-426 line of pipe-rolling plant possessing an MPM mandrel mill with retained mandrel and two-roll mill housing. [ABSTRACT FROM AUTHOR]

With continuing growth in Russia's industrial and civil construction industry and the introduction of new technologies, the production of corresponding rolled products must be increased; this is true, in particular, of rebar. Rebar production on existing mills may be quickly expanded, without major capital expenditures, by means of rolling and splitting. The conditions for its practical use are investigated. New formulas are derived for the longitudinal force corresponding to the frictional forces in creating the crosslinked initial profile, for subsequent splitting; these formulas take account of the profile's geometry and the conditions of shape change. [ABSTRACT FROM AUTHOR]

The influence of pulsating dynamic loads at nonstationary self- and parametric oscillations in surface layers of the parts under plastic deformation regarding the quality of finished products after cold rolling, knurling, breaking-in, drawing and punching has been provided. In order to describe the parametric interaction effects between the tool and the workpiece, a schematization of the technological process is adopted, in which the workpiece bulk or a part manufactured from it serves as an anisotropic medium. This is elastically bound to the contact's surface of the outer hardened layers with the inner bulk of the part. Based on the proposed physical model, the conditions have been determined that lead to failure of integrity, manifestation of cracking and corrugation of external fibers during the hardening process. The second dynamic problem for the surface layers is formulated and solved at the interface between the machined hardened outer layers and bulk of the workpiece. The frequency and amplitude characteristics of unstable parametric oscillations have been found, which lead to deterioration of the quality of finished products. Measures to reduce vibration activity in the interaction zone between the tool and the workpiece, and in the power elements of machines for cold metal working have been suggested. [ABSTRACT FROM AUTHOR]

The formative patterns of gaps between turns of cold-rolled strips in rolls and the ways these gaps affect the stress-and-strain state (SSS) of these rolls are disclosed. The effects of surface roughness, temperature, physical mechanical properties, strain degree, and hardening of cold-rolled steel on the interturn gaps in and the roll's SSS are analyzed in detail. Possibilities of affecting the roll's SSS by adjusting the cold-rolling temperature of fine strips and tinplate are exposed. Recommendations on choosing thermal-speed modes of strip rolling and coiling are presented. [ABSTRACT FROM AUTHOR]

In modern high-technology industry, pipe bending technology is widely used. Pipe bends are an integral part of pipeline systems. The most widely used methods are techniques of cold pipe bending accompanied by a number of negative phenomena such as reduction in the wall thickness on the outer side of the bend, ovalization of the cross section, and formation of crimps. The article presents a study of the influence of deforming pipe billets by rolling under high tension on the structure and properties of the billet's material. The pipe deformation by rolling under tension allows obtaining radially bent billets without destroying them and without causing obvious defects on the surface and microstructure. The tests were conducted using samples manufactured of 3sp (ASTM 284 grade D) and 12Cr18Ni10Ti (UNS S32100) grade steels. The microstructure was examined in accordance with GOST 5639–82 state standard, the mechanical properties were investigated in accordance with GOST 1397–84, and the microhardness—in accordance with GOST 9450–76. The effect of geometry changes of the pipe billets on their structure and properties was studied. It is shown that the pipe deformation by rolling leads to changes in the mechanical properties of the tested materials. The microhardness and strength values increase, while the grain points decrease. In the course of deformation, the microstructure of the material may change as a result of structural transformations (quenching). The plastic flow of the metal during the thermomechanical deformation suggests possible change in the pipe wall structure as a result of recrystallization and heat treatment of the material in the bend area, which requires further study and in-depth analysis of the technology in question. [ABSTRACT FROM AUTHOR]

The tension modes of cold-rolled strip coiling are analyzed. The dependences of the stress-strain state of the coils on the strain degree, temperature, velocity, strip rolls surface roughness during cold strip rolling are considered. Coiling methods provide improvement of production efficiency and the quality of cold-rolled sheet steel by preventing the appearance of such rolling defects as bent fractures and coil shape defects. [ABSTRACT FROM AUTHOR]

The influence of the one-time reduction in the first pair of matched grooves in a three-high stand on the cracking at the end of the billet is simulated. The traditional six-pass procedure in the three-high stand is compared with the new six-pass procedure and the eight-pass procedure proposed in the present work. The comparison shows that, by milder reduction in the first pair of matched grooves, the effective stress may be decreased, along with the likelihood of cracking at the end of the billet. The damage at the ends of the multiple billets in the three-high roughing stand may be minimized by means of further decrease in deformation in the first passes on rolling multiple continuous-cast billets made of high-quality structural steel, along with decrease in the initial rolling temperature and division of the billet into measured lengths on a band saw. [ABSTRACT FROM AUTHOR]

The industrial production of low-carbon microalloyed steel plates (thickness 150-200 mm) on the NLMK Dansteel 420 reversible rolling mill is considered. Such plates are intended for operation at temperatures between-50 and +450°C in high-pressure equipment. The technologies used for steel casting and thick-sheet production ensure stable strength over the whole sheet thickness at 20-450°C, with satisfactory impact strength between +40 and-50°C. The research results are used in certification on the basis of TUV Pressure Equipment Directive (PED) DGR 2014/68/EU and the AD2000 directive regarding the production of rolled P355N, P355NH, P355NL1, and P355NL2 steel sheet of thickness up to 200 mm. [ABSTRACT FROM AUTHOR]

The stages of structure formation during cold rolling are investigated in bcc (110)[001] single crystals of Fe-3% Si alloy, within the deformation zone. To obtain a visible deformation zone, the laboratory mill is abruptly stopped at the instant of sample rolling. To reduce the frictional coefficient, lubricant is used for some of the samples. The deformational structure is studied by metallography and orientational electron microscopy (EBSD). Deform-3D software is used to analyze the relation between the experimental data and the calculated stress state in rolling, for various values of the frictional coefficient. Depending on the frictional coefficient, the stress state may significantly affect the mesostructure formation and the texture development. In a single crystal rolled with elevated friction, when the deformation is relatively small, deformation bands are formed. Orientational analysis of the contact point of deformation bands reveals alternating microbands, each with slight different orientation, which are separated by small-angle boundaries. In the rolling of a (110)[001] single crystal with lubrication (reduced friction), twinning is observed even with slight deformation. The twinning is evidently due to the reduced contribution of surface energy to the total energy of twin nucleation. Throughout the whole deformation process, either the twins of both systems retain the strict Σ3 crystallographic relation with the matrix or else, on account of the local lattice reorientation, Σ3 disorientations are converted to similar special Σ17 b and Σ43 c disorientations. On the basis of experimental data, a dislocation model is proposed for the formation of deformational mesostructures in the cold rolling of a (110)[001] single crystal. This model includes the formation of microbands in the initial stage of deformationband generation; the formation of transition bands parallel to the rolling plane with the dynamic retention of the initial orientation; and the formation of transition bands inclined to the rolling plane with a habitus parallel to the {112} matrix plane. These inclined planes are equivalent to shear bands whose habitus is inclined at ~17° to the rolling plane. [ABSTRACT FROM AUTHOR]

The localization of plastic strain in the extension of 08ps low-carbon steel is compared after hot rolling and after electrolytic saturation with hydrogen by means of a three-electrode electrochemical cell. Analysis of the strain curves shows that they include a plasticity region, a stage of linear strain hardening, and a stage of parabolic strain hardening (Taylor hardening). Double-exposure speckle photography is used to visualize the localized strain zones. On that basis, the quantitative deformation characteristics may be obtained. In other words, the displacement-vector field in a plane sample under extension may be determined, and then the components of the plastic distortion tensor (the local elongation ε, shear ε, and rotation ω) may be calculated. The basic types of plastic flow localization are identified at different stages of strain hardening, and their parameters are determined. [ABSTRACT FROM AUTHOR]

Despite the very diverse types of rails in industrial use, practically the same groove configurations may be used in rolling. However, the system used for streetcar girder rail is somewhat different. Computer simulation and industrial experiments permit the investigation of the axial-porosity distribution and assessment of the deformed state of the rolled metal in roughing and finishing. On that basis, a new rolling technology for streetcar girder rail has been developed. In the industrial research, the axial-porosity distribution in rolling with box grooves of the BD-1 roughing cell and slotted grooves in the BD-2 cell is investigated. The macrostructure is investigated on templates taken from the continuous-cast billet after the second, seventh, and ninth passes in the BD-1 and BD-2 cells. The results of computer simulation and the industrial trials are in good agreement. [ABSTRACT FROM AUTHOR]

Engineering formulas for the basic technological parameters when rolling I beams in universal grooves are derived on the basis of the variational principle of minimum total power. Those parameters are the increment and reduction of the flanges; the contact pressure at the horizontal and vertical rollers; and the rolling forces and torques. [ABSTRACT FROM AUTHOR]

Billet of square or rectangular cross section is rolled in grooves on bar mills. The degree of reduction and the shape of the grooves determine the stress state of the metal in the deformation region and the energy consumption in rolling. The tensile stress at the bar surface depends on the longitudinal and transverse deformation. Under the action of the tensile stress, the integrity of the metal surface may be disrupted. For each steel, there is a limiting strain beyond which the bar surface disintegrates. The ratio of the current strain to its limiting value determines the degree to which the metal's reserve of plasticity has been depleted; that, in turn, characterizes the probability of defect formation at the metal surface. The optimal groove configuration may be selected by simulation of the rolling conditions and assessment of the metal's plasticity and the energy consumption. [ABSTRACT FROM AUTHOR]

Systems for reducing the width of continuous-cast slab supplied to broad-strip hot-rolling mills are reviewed. It is found that the use of vertical scale removers with smooth rollers, without smoothing in horizontal rollers, is laborious and ineffective. The use of smooth vertical rollers and a series of horizontal rollers, which is a configuration often used outside Ukraine, permits reduction in slab width by no more than 150-200 mm. Systems with vertical grooved rollers and horizontal smoothing rollers prove the best. Optimal conditions for reducing slab width are proposed, and parameter values of the corresponding equipment are recommended for the 2000 mill. [ABSTRACT FROM AUTHOR]

New and traditional hot-rolling mills are compared. Calculations show that the position of the intermediate coiling system in traditional broad-strip mills does not permit sufficient efficiency. A new design is proposed to make better use of the strip temperature, produce strip with negative tolerances, and reduce power consumption. [ABSTRACT FROM AUTHOR]

Research on the energy and kinematic parameters of complex rolling processes is reviewed. Means are proposed for reducing the rolling forces and improving the surface quality of the strip by complex rolling, as well as minimizing roller-replacement rates. [ABSTRACT FROM AUTHOR]

Trends in the production of rolled strip, pipe, and other components in Russia between 2010 and 2012 are surveyed, with a particular focus on cold-rolled sheet, coated sheet, bar, and rail. Successes are noted, and quality products are discussed. The importance of staff training and motivation is emphasized. [ABSTRACT FROM AUTHOR]