Application of physical simulation at study of pipe production processes

Physical experiments allow to obtain maximum information on a studied process at minimal cost, ensuring its higher accuracy comparing with data, obtained by mathematical simulation and avoiding risks, which can occur at industrial testing of new technological modes. Results of studies of deformation in the process of pipes production by extrusion presented. The studies were accomplished at laboratory test units, developed by specialists of the laboratory of drawing and extrusion of JSC “RusNITI”. One of the basic problems at pipes production by extrusion is ensuring minimal possible wall non-uniform thickness. It was noted that the relation between plunger die moving speeds during sleeve pressing-out and immediate pipe extrusion has a significant effect on pipe wall non-uniform thickness. Computer simulation of the pipe extrusion process, accomplished by application QForm program shown that minimal values of wall non-uniform thickness corresponded to relation abovementioned speeds as 0.5–0.8. To check the data, a physical simulation of extrusion process of lead cylinder samples, having outside diameter of 18.94 mm and wall thickness 5.19–5.32 mm was accomplished. For the extrusion, a universal servohydraulic system of dynamic test Shimadzu Servopulser was used. Within the physical experiment a dependence was established between pipe wall non-uniform thickness on relation between speeds of pressing-out and extrusion. The revealed regularity was confirmed during pilot production of a pipe lot at the 55 MN force extrusion line. Another physical simulation of extrusion of 10.0×2.0 mm pipe-samples made of C1 grade lead was accomplished with one- and twothread helical ribbing of internal surface. For its accomplishment an experimental module was designed and manufactured. It was established that rotation speed of the extrusion mandrel had no significant effect on extrusion force. Metallographic studies shown that the extrusion mandrel rotation speed contributes to considerable increase of pipes surface hardness and obtaining finer grain comparing with the classic extrusion method. The technical ability of pipes production with internal helical ribbing by hot extrusion method was confirmed. The results of the study became a base for elaboration of a technology of pipes production at Volzhsky pipe plant according to ТУ 14-3Р-157–2018 “Steel seamless hot-extruded pipes with helical ribbing of internal surface for steam boilers”. Results of physical simulation of pipe drawing process at self-adjusting mandrel with application of lubricant materials of various viscosity. The data obtained were used for elaboration of a technology for production of cold-deformed pipes with internal diameter of 6.0–12.0 mm at Sinarsky pipe plant.

Increase of resistance of piercing mill mandrels at seamless pipes production of 13Cr grade martensite class stainless steel at line ТПА 159‒426 of JSC VTZ

At production of pipes of type 13Cr grade steel used at development of oil and gas deposits in areas with aggressive environment, intensive wear of instrument takes place, first of all, piercing mill mandrels. Factors, influencing the resistivity of the piercing mandrels considered, including chemical composition of the material, the mandrel is made of and its design. Based on industrial experience it was shown, that chrome content in the mandrel material practically does not affect on the increase of its resistivity, since the formed thin protective oxides having high melting temperature, are quickly failed and practically are not restored in the process of piercing. To increase the resistivity of piercing mandrels at production of casing tubes of type 13Cr grade steel, a work was accomplished to select a new material for their manufacturing. The chemical composition of steel presented, which was traditionally used for piercing mandrels manufacturing, as well as a steel grade proposed to increase their resistivity. First, molybdenum content was increased, which increases the characteristics of steel strength and ductility at high temperatures and results in grain refining. Second, tungsten content was also increased, which forms carbides in the steel resulting in an increase of its hardness and “red resistivity”, as well as in preventing grains growth during heating. Third, cobalt content was also increased, which increases heat resistivity and shock loads resistivity. The three elements increase enabled to increase the mandrels resistivity by two times. Results of mandrel test of steel 20ХН2МВ3КБ presented, the mandrel having corrugation on the working cone surface, which enabled to reach the resistivity growth to 12 passes without significant change of instrument cost. Microstructure of mandrels made of steels 20Х2Н4МФА and 20ХН2МВ3КБ shown. Application of the centering pin of special design was tested, which provided forming of a rounding edge on the front billet ends, eliminated undercut of mandrel external surface in the process of secondary billet grip and increase the service life of the piercing mill mandrels. At production of seamless pipes of martensite class type 13Cr stainless steels having L80 group of strength, an increase of piercing mandrel resistivity was reached by more than four times, which together with other technical solutions enabled to increase the hourly productivity of the hot rolling section of Volzhsky pipe plant ТПА 159-426 line by more than two times.

EZTM experience in designing and manufacturing of rolling mill main drive gearboxes

The experience of the Electrostal Heavy Machinery Plant (EZTM) in designing and production of special gearboxes and gear stands for main drive of various rolling mills is summed up. The specifics of section and ball-rolling mills, piercing and reduction mills, mills for cold rolling of tubes and mills for the production of reinforcing bars are considered. It was shown that at designing of special gearboxes for the main drives of rolling mills, the designer, taking into account the parameters of the mill, must build a cyclogram of their loading, which depends both on the range of rolled products and on the variability of loads within the rolling cycle of one billet. In the Designing Department of EZTM, the strength calculation of gears of different types is carried out in the REDUK 4.3 software package, which allows performing strength calculations of gears taking into account the expected loading cyclogram. At the same time, the program provides the initial data for calculating the shafts and bearings, i.e, the forces in engagement and the rotational speed of each of the shafts for the first stage of the cyclogram. The geometrical parameters of the gears are optimized according to the criterion of contact and flexural strength, both between the stages and within each of them.The load sequence diagram depends both on the range of rolled products, and variable loadings in a rolling cycle of a workpiece. Geometric parameters of gears are optimized by contact and bending equal strength, as between the stages as within each of them. Carburizing, hardening and grinding of teeth are provided and secured technologically. Currently, the gearboxes manufactured by the plant are successfully operated at many metallurgical enterprises, both in Russia and abroad. Among them, the gearboxes of main drive of the piercing mill of the Seversk Pipe Plant, the mills for cold rolling of tubes in the USA and China, the section mills at the Yartsevo Casting and Rolling Plant, the reduction mill at the Dnepropetrovsk Metallurgical Plant, etc.

Smelting of steel semi-product in BOF and EAF under magnesian slags

Basics for the development of a rational composition of the main magnesian slags and technological methods for their formation according to the periods of BOF bath blowing and the periods of smelting in EAF are the results of fundamental studies of the slags physicochemical properties. Implementation in the converter shop of OJSC “EVRAZ NTMK” of a developed set of technological methods of magnesian slags formation in the main period of blowing and a wearresistant skull on the basis of magnesian final slags ensured record durability of converter linings. These slags have low aggressive effect on the lining of converters, while maintaining high refining properties. The durability of the converters’ lining exceeds 7000 heats, while maintaining high technological and technical-economic indicators of the process. During heats of low manganese cast irons in 350-metric ton heavy converters of JSC “EVRAZ ZSMK” under magnesian slags, the features of slag formation and changes in chemical composition of the slag were studied by the periods of the BOF bath blowing. During the process stage of phosphorous cast irons in 300-metric ton BOF at JSC “ArcelorMittal Temirtau”, a set of technological methods was developed for the formation of magnesian slags of the recommended chemical composition by the periods of phosphorus cast irons blowing and wear-resistant skulls based on final magnesian slags of moderate basicity. The implementation of the developed technological methods ensured the lining stability of BOF of more than 5 000 heats while maintaining high technological, technical and economic indicators of phosphorous process stage. In the EAF shop of PJSC “Seversky Pipe Plant” a technology for the formation of magnesian slags of rational composition was developed over the smelting periods in EAF-135. Introduction of the technology ensured the record resistance of the refractory lining of the furnace up to 1900 heats per campaign and high level of technological and technical-economic indicators of the process.

OXIDATIVE REFINING OF MOLTEN STEEL USING THE WELDING FLUX WASTE

The possibility of using welding flux of the Volga pipe plant (VTZ) to improve the process of oxide refining of steel was considered.

ASSESSMENT OF HARMFUL INDUSTRIAL FACTORS ON THE WELDER , 5TH GRADE

The influence of harmful and dangerous production factors on the electric and gas welder of the 5th category of the Irkutsk pipe plant is considered

Methodological Toolkit for Environmental and Economic Assessment of Metallurgical Enterprise Activities

The growing impact on the environment from industrial enterprises, the depletion of non-renewable natural resources and the associated risks make it relevant to take into account the environmental performance indicators of the enterprise along with economic ones. The authors believe that it is possible to conduct an environmental and economic assessment of the enterprise using an integrated indicator. The purpose of this paper is to develop a methodological toolkit for conducting an integrated environmental and economic assessment of the activities of a metallurgical enterprise, which makes it possible to make both a retrospective assessment of the enterprise's activities, and a predictive one based on the parity between the economic and environmental spheres of the enterprise. An analysis of domestic and foreign literature showed the absence of a unified approach to environmental and economic assessment of industrial enterprises based on standard financial and environmental reporting, and non-financial reporting standards. The methodology proposed by the author includes two blocks of indicators: an environmental and an economic one. The environmental block is represented by indicators related to the environmental impact. The economic block includes various indicators of the profitability of the enterprise. The authors propose an approach to standardizing indicators and calculating the integral indicator of environmental and economic assessment for the period. A distinctive feature of the author's methodology is the development of a single indicator that combines heterogeneous and multidirectional indicators of the environmental and economic blocks, which makes it possible to assess how the state of the enterprise changes over time, considering the action of various factors and their influence on the changes occurring at the enterprise. The proposed methodology was tested in application to the Seversky pipe plant for the period of 2016–2018. It showed a deterioration in the final environmental and economic assessment of the enterprise's activities as per the indicators of the economic block. At the same time, almost all indicators of the ecological block improved over the period of observation. The result is attributed to the ongoing large-scale technological overhaul at the enterprise, aimed, in many respects, at reducing the impact on the environment and increasing the efficiency of the enterprise. The authors believe that after the completion of the modernization project, an increase in the production volume and a decrease in unit costs with a minimum impact on the environment will help to achieve a balance between the ecological and economic spheres of the enterprise.

METAL FORMING DURING PIPES REDUCTION ON A THREE-HIGH ROLLING MILL

Pipe rolling plants (PRP) with three-high screw rolling mills are used to produce hot-rolled seamless pipes. In Russia, two such rolling units are used: PRP 160 at Pervouralsk Novotrubny Plant and PRP 200 at Volzhsky Pipe Plant. Recently, the most acute issue is increasing their technological capabilities. There is a need of expanding size and grade mix, as well as non-traditional use of gauge and rolling mill for screw rolling. The paper presents results of experimental study of the process of reduction or un-adjusting rolling of pipes on three-high screw rolling mills with an increase in reduction of diameter up to 25 %. The results of computer finite element modeling in QFORM program are provided. The aim of this work was to study effect of rolling process with increased reduction in diameter on change of metal form in deformation zone and changes in geometrical dimensions at reduction of cups with different wall thickness on the pilot mill. Important role in process of metal forming during screw rolling (especially when rolling hollow products and pipes) plays cupped blank ovality that is equal to the ratio of the roll radius when the metal comes in contact with the roller to the radius under the roller in the cross section of deformation zone. Ovality characterizes stability of change in geometric dimensions of pipes and their resistance to deformation in inter-roll space. The reduction of thin-wall cupped blank is accompanied by large va lues of ovality, deformation process is less stable, and as a result, form defects (faceting) and end defects occur during plug rolling. Ovality at plug rolling increases more intensely in comparison with plugless rolling. Presence of plug limits displacement of metal in axial direction and contributes to displacement of metal in gaps between rollers. At plugged rolling, it is necessary to use rolls with collars allowing main reduction along the wall, thereby localizing reduction zone on the plug, and reducing ovality of cupped blanks.

Elaboration and mastering of technology of semiproduct smelting in EAF under magnesia slags

Technology of magnesia slags forming provides increase of electric energy utilization efficiency and furnace lining resistance due to early formation of stable slag foam and decrease of aggressive slag impact on the lining. At the same time the practice of operation with magnesia slags shows, that excessive over-saturation them by magnesium oxide results in heterogenization, decrease of refining properties and deterioration of some technological, technical and economic process indices. Therefore, study and elaboration technology of rational composition magnesia slags forming by periods of a heating in EAF is an actual task. Results of numerical simulation of slag temperature and chemical composition effect on MgO saturation concentration during different melting periods in EAF presented. Besides, results of analysis of refining abilities of magnesia slags depending on MgO saturation degree also presented study of magnesia slags viscosity effect depending on MgO basicity and saturation concentration, as well as magnesia slag chemical and phase composition effect on foaming efficiency. Results of theoretical and experimental study were used as a base of elaboration rational slag composition by periods of melting in the EAF and technological techniques of their formation. A technology elaborated and implemented at PAO “Seversky pipe plant” EAF shop by leaving some amount of high-magnesia slags of the previous heat and addition in two stages high-magnesia flux of “Magma” grade during the oxidizing period. This resulted in a record resistance of the refractory EAF lining, exceeding 1900 heats within a campaign and a high level of technological, technical and economic process indices.

STRESSES IN ANVILS OF VARIOUS CONSTRUCTION OF CONTINUOUS CASTING AND DEFORMATION PLANT AT PRODUCTION OF SHEETS FROM STEEL FOR WELDED PIPES

A comparative assessment of strenuous state of the anvils with and without channels has been carried out for the installation of combined continuous casting and deformation process in the production of steel sheets for welded pipes. The conditions of operation and loading of the anvils of combined continuous casting and deformation process are described. The design of anvil with channels for water cooling and the nature of its loading are given. Using the algorithm for solving problems in the elasticity theory by finite element method, the laws governing the distribution of axial stresses in anvils from the slab reduction force are determined. Effect of the channels for anvils cooling with water on the magnitude and nature of stresses distribution in them from the stress of the slab reduction was estimated. The calculation results of temperature fields and axial and equivalent thermoelastic stresses in anvils with channels are presented for the production process of steel sheets for welded pipes in a combined continuous casting and deformation unit. The article considers regularities of total stresses distribution in anvils with channels. To assess the effect of anvils structure on their stress state, regularities of distribution of thermoelastic and total stresses in strands without channels have been determined. The graph of dependence of thermoelastic stresses in the anvil on temperature of its contact surface is given. Recommendations for choosing the material of the fighters are given. The advantages and disadvantages of the anvils with channels for the unit for combined continuous casting and deformation are described. The parameters of such a pilot installation are presented. The authors also describe the results of an experimental study of the parameters of a combined process at the manufacture installation for continuous casting and deformation of JSC Ural Pipe Plant.