Flow of molten metal to the mold of continuous casting machine (CCM) is an insufficiently studied process up to the present  day. This paper is a continuation of author’s works published in  scien tific se rials last years. It shows the possibility of a theoretical  research of motion kinetics and thermal flows of molten metal in the  mold during traditional casting by using hydrodynamic theory and  mathematical physics equations and a proven numerical approach.  This familiar calculation methodology makes it possible to calculate  flows of molten metal motions and their temperatures in the mold  and to compare the obtained results with ones obtained during usage  of other methods of metal pouring including proposed method. This  paper describes and solves three-dimensional problem of determination of velocity and temperature fields in metal poured to CCM mold  from the submerged nozzle to the round deflector. In addition, the  calculation methodo logy described in previous works of the authors  is used, namely, the constitutive equation system, numeric method,  numerical scheme and algorithm for solving the problem. Hardened  metal crust forming on the mold faces was not considered in this  calculation. For the results objective analysis of the problem solving  in two ways (traditional and proposed), the same theoretical (speed  of pulling-out from crystallizer) and geometrical parameters of rectangular cross-section mold were taken. Application for an invention for the described alternative method of liquid metal supplying to  rectangular mold was registered (No.  2018108974/02 (013808)). The  article contains some results of numerical solution of the problem in  particular schemes of molten metal flows and their temperatures over  different sections of the mold.

 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.

The paper states urgency of the problem of determining stressstrain state of metals of the cladding layer and the main strip in  production of three-layer bimetal: alloyed steel-constructional steelalloyed steel. Temperature field of the main strip and cladding layer  is given to calculate stress-strain state of metals of three-layer bimetallic strip. Initial data for calculating this stress-strain state are  given. To assess the effect of coefficient of friction between cladding  layer  s and the main strip on stress-strain state of metals in deformation zone, three values of it are taken. Geometric model is described  for calculating stress-strain state and metal flow in deformation center of cladding layer. Characteristic lines and points of calculation are  provided. Technique for solving the problem of determining stresses  and flows in deformation focus is described by finite element method  using ANSYS app. Regularities of flow of cladding layer’s metal  along the length of deformation center and movement of the main  strip of bimetallic ingot are given. Values   of mutual displacement of  layers of bimetallic strip are determined as a function of deformation  degree of the cladding layer. And the recommendations are given on  this degree to improve quali ty of a three-layer bimetal. Regularities  of distribution of axial and tangential stresses in deformation center  are presented for production of steel three-layer bimetallic strips in  the unit of combined continuous casting and deformation. Stress state  of the cladding layer’s metal in focus of cyclic deformation was estimated from the position of improving quality of three-layer bimetallic strips produced in such unit.

Influence of the chemical composition of CaO – SiO2 – B2O3 oxide system containing 15 % Al2O3 and 8 % MgO (in this expression  and hereinafter indicated by mass %) on viscosity and crystallization  temperature was studied using experiment method of simplex lattice  planning. Addition of B2O3 to the slags of oxide system expands the  range of slags composition with a low crystallization temperature and  viscosity. Slags with a basicity of 2  –  3, containing 1  –  3  % of B2O3  are characterized by a low crystallization temperature, varying from  1400 to 1450  °С and have high flowability. The viscosity of such slags  when heated to 1550 and 1600  °C does not exceed 0.20 and 0.15  Pa·s,  respectively. An increase in B2O3 content to 4  –  6  % in slags with a  basicity of 2  –  3 is accompanied by a decrease in crystallization temperature to 1350  –  1425  °C with keeping low, not more than 0.15  Pa·s,  viscosity in the range of heating temperatures at 1550 and 1600  °C.  The displacement of formed slags containing 1  –  6  % of B2O3 to the  area of increased basicity up to 3  –  5 preserves their relatively high  fluidity. In this case, with an increase in B2O3 concentration, there is a  clear tendency for the studied oxide system to shift to the region of low  crystallization temperatures. Crystallization temperature of slags with  basicity of 3  –  4 containing 6  % of B2O3 reaches 1400  °С and practically does not exceed 1475  °С of slags with basicity of 4  –  5 containing 1  –  2  % of B2O3 . At temperature of 1600  °C, the viscosity of such  slags varies from 0.15  Pa·s with a basicity of 3 and a content of 5  –  6  %  of B2O3 to 0.25  Pa·s in the basicity range of 4  –  5 with B2O3 content  of 1  –  3  %. A decrease in temperature of the studied oxide system by  50  °C is accompanied by a slight (no more than 0.05  Pa·s) increase in  viscosity.

Industrial wastes, accumulating in a dumping ground, have useful technical properties in many cases, so they can be considered as  secon dary resources. The investigation of slag properties and modifications in different conditions needs a complex approach that includes X-ray phase, electron microscopic and petrographic analyses.  The research aim is to substantiate the resource value of Zaporozhstal  PJSC dump blast furnace slag on the basis of chosen experimental  methods. X-ray phase analysis allows us to discover the minerals of  blast furnace slag that are crystalline: rankinite 3CaO·2SiO2 , quartz  SiO2 , helenite 2CaO·Al2O3·SiO2 , bredigite α-2CaO∙SiO2 , okermanite  2CaO·MgO·2SiO2 and pseudowollastonite α-CaO·SiO2 . The minerals  okermanite, bredigite and pseudowollastonite are technically useful to  produce binders as they are hydraulically active. The mass fraction  of a vitreous component, which composes half of blast furnace slag  mass of Zaporozhstal PJSC, was computed. Amorphous phases testify  on the higher sorption and chemical slag activation that are important  in terms of the use of slag to produce binders. The mass contribution  of amorphous substance state is slightly higher in large fraction slag.  Microphotographs of the surfaces of blast furnace slag particles show  high loosening degree and needle-shaped and lamellar crystallines that  stipulate sorption properties of the slag. The dump blast furnace slag of  Zaporozhstal PJSC can be recommended to produce binders – Portland  cement and Portland slag cement – at totality of chemical parameters:  high concentration of hydraulically active minerals and amorphous  phase, highly developed surface of slag particles and surface sorption  activation.

The change in phase composition and fine texture occurring in the  ferritic-pearlitic 0.18C – 1Cr – 3Ni – 1Mo – Fe, 0.3C – 1Cr – 1Mn – 1Si – Fe  and 0.34C – 1Cr – 1Ni – 1Mo – Fe steels under electrolytic plasma carbonitriding  was  investigated  by  transmission  electron  microscopy  (TEM) method conducted on thin foils. Carbonitriding was implemented by surface saturation with nitrogen and carbon in aqueous  solution under the temperature of 800  –  860  °C during 5  minutes. All  steels were investigated before and after carbonitriding. It was ascertained that in the original state steel is given as a mixture of grains  of pearlite and ferrite. Carbonitriding has led to creation of modified  layers: the bigger was the amount of pearlite before the beginning of  carbonitriding, the thicker was modified layer. Carbonitriding resulted  in significant qualitative changes in phase state and structure of steel.  It was revealed that in the surface area of modified layer along the  matrix, there were also particles of other phases: carbides, nitrides and  carbonitrides. In the course of removing from the surface of carbonitrided sample, their complete set and volume fractions decrease and at  the end of modified layer only one carbide phase is present in all steels,  i.e. cementite. It was found that matrix of all steels after carbonitriding is tempered packet (lath) and lamellar martensite. In the surface  area of carbonitrided layer the volume fractions of lath and lamellar  martensite depend on the original state of steel – the bigger was the  amount of pearlite in steel the less lath martensite and the more lamellar martensite was formed. Such a dependency cannot be observed in  the central area, and at the end of carbonitrided layer volume fractions  of martensite packets and plates are commensurate.

In modeling of shrinkage processes during solidification and  cooling billets on the continuous casting machine there is a need to  determine values of coefficient of linear expansion, depending on  temperature and carbon content. Experimental data to coefficients of  line ar expansion given in reference literature are in most cases limited to a low-temperature interval, the upper limit of which does not  exceed 1200  °C. The values of this coefficient are unknown for high  temperatures. Their calculation definition is carried out recently with  the use of empirical dependences for calculation of change of phases’  specific  volumes  at  temperature  changes.  However,  dependencies  given in the literature are often contradictory. In this regard there was  a need to develop a unified method for determining values of linear  expansion coeffi  cient depending on temperature and carbon content.  In derivation of formulas for calculation of linear shrinkage coefficient, the pre viously obtained expressions for calculation of specific  volumes of Fe – C alloys were taken as a base. Since the change in  specific volume with the temperature significantly affects carbon content, calculation of linear shrinkage coefficient is performed separately  for three intervals of carbon concentrations: 0  –  0.10  %, 0.10  –  0.16  %  and 0.16  –  0.50  %, differing from each other in various phase transformations during solidification and cooling of alloys. An example of  calculated determination of linear shrinkage coefficient is given for  the midpoints of specified intervals. Comparison of the obtained calculation results with known literature and reference data was made.  Adequa cy of the proposed technique was established and possibility of  its use for the research problems solving is shown.

Fatigue strength of widely used engineering structural steels was  studied at various frequencies of loading according to the scheme of  cantilever bending of the rotating cylindrical samples. Fatigue resistance index is tangent of angle of inclination of fatigue curve to axis  of longevity. It is established that 40 and 45 steels belong to the group  of materials in which decrease in frequency of loading leads to cyclic  softening and decrease in fatigue resistance, which is numerically expressed by increasing slope of fatigue curve. Tests of the samples made  of 40X steel had shown that increase in frequency of loading cycles  leads to a noticeable decrease in slope of fatigue curve parameter, i.e.  to an increase in fatigue resistance. Decrease in fatigue resistance parameter is associated with an increase in hardening of material of the  samples (parts) surface layers which reduces fatigue damage to the  surface itself. Dependence of the fatigue curve slope tangent on surface damage at changing loading cycles frequency is shown and it is  stated that, regardless of frequency, damage of material surface layers  increases along the slope of fatigue curve. For each of these groups  mathematical relations are defined. The correlation coefficient providing degree of convergence of experimental results with the constructed fatigue curve was adopted as a criterion of cyclic behavior stability  of steels. It is revealed that increase in behavior stability of 40X steel  is observed with increase in cyclic deformation rate. Tests of 45  steel  have shown that decrease in cyclic strength with increase in loading  frequency does not affect fatigue stability of material. Increased dispersion of experimental results was observed in 40 steel at low loading  frequency, despite the high values of cyclic strength at given loading  frequency. On the basis of conducted experiments, dynamics of behavior of real machine parts and structures subjected to cyclic loads  operating was determined in the studied loading spectrum.

Increasing performance of steelmaking units is possible with  changing methods of steel production. Such variances entail serio us  changes in the subsequent redistributions: in metals processing by  pressure and in thermal treatment of finished metal products. It is  known that these two metallurgical processes are equipped with a  large number of heating and thermal furnaces, and their thermal work  does not always meet increased requirements for products quali ty.  Issues of improving thermal performance of furnaces are also relevant in mechanical engineering. High technological requirements  are associa ted with very strict environmental ones. Therefore, a new  concept is needed for the design and construction of modern highly  automated industrial heating furnaces. In order to improve the design  and technical and economic indicators, technical obsolescence and  the construction of new industrial furnaces are carried out. In design  and construction of furnaces, fuel-burning devices of new designs  and modern materials are used. In turn, this necessitates the use of  new approaches to working space and heating system design of the  furnace, taking into account arrangement of heated products charge.  Such events are carried out, as a rule, in operating workshops, that  causes certain difficulties due to limited space provided for placement of new furnaces and equipment for their operation and maintenance. A complex study was made of the design and thermal performance of a block of three chamber thermal furnaces. They were built  in a limited space of the workshop with specific loading and delivery  of heated thin sheet.

Rolling process is carried out due to power supplied to the center  of deformation using contact friction forces. Rolling takes place in two  stages  – the capture stage and the steady-state process. The capture  stage determines possibility of deformation in rolls. During this period,  retracting forces of friction are used with maximum efficiency. The  main stage of rolling is the steady-state stage of the process, where  contact friction capabilities are not fully used and reserve of friction  forces is created, which can increase efficiency of rolling process. To  balance excessive friction forces on contact surface in deformation  zone during the steady-state process, zones of advance and adhesion  appear. Their length characterize amount of excessive friction forces.  Theoretical dependences for determining slip and adhesion zones are  given taking into account variety of rolling factors. Estimation indicator of abilities of friction forces reserve at the steady-state stage is  offered as well as dependence for its definition. It is analytically established that in steady-state stage of rolling on smooth rolls with ratio    α/μз  =  1 it is possible to supply 1.7  –  2  times greater energy due to  exis ting reserve of friction force than at the stage of capture at a lower  ratio α/μз ; these numbers are even higher for rolling on grooved rolls.  Dependence which determines amount of additional power provided  by friction forces reserve is given. Promising directions of using friction forces reserve at the steady- state stage of rolling are provided to  improve its efficiency. On the example of rolling in drive – non-drive  stand, an increase in efficiency (Efficiency Ratio) of the main line of  rolling mill is established with more efficient use of friction forces  at the steady-state stage of rolling process. Theoretical dependences are given to determine Efficiency Ratio at usual rolling process and at  more full use of friction forces reserve.

In  modern  high-tech  industry,  flexible  pipe  technology  is  widely used. Pipe benders are an integral part of pipeline systems.  The most widely used are methods of pipes cold bending, which are  accompanied by a number of negative phenomena – such as reduction in the crackle of the wall on outer side of the bend, ovalization  of the cross section and formation of bumps. The article presents a  study of influence of deformation technology of pipe billets by rolling with high tension on the structure and properties of the billet’s  material. The method of pipe deformation by rolling with tension  allows obtaining radial bending of the billet without its destruction  and without causing obvious defects of the surface and microstructure. The tests were carried out on the samples from steel of 3sp and  12Kh18N10T grades. Research of the microstructure was performed  in  accordance  with  GOST  5639  –  82,  of  mechanical  properties  –  with GOST  1397  –  84, of microhardness  – with GOST  9450  –  76.  The article examines the effect of changes in geometry of the pipe  billet on its structure and properties. The process of pipe deformation  by rolling leads to changes in the mechanical properties of the tested  materials. The values   of micro hardness and strength increase, while  the grain points decrease. In the process of deformation, it is possible  to change the microstructure of the material as a result of structural  transformations (quenching). In the thermomechanical method of deformation, plastic flow of metal suggests possible change in structure  of pipe walls as a result of recrystallization and heat treatment of material of the bend area. Therefore, it requires further study and more  in-depth analysis of this technology.