Research of the cutting process of rolled section steel on rail-beam and large-size rolling mills

Improving the quality of rolled steel products is the primary task of the entire steel industry. As the main step of rolled steel production, hot rolling has received extensive attention. As far as the hot rolling process is concerned, the chemical composition of steel and related process parameters are the most direct factors affecting the quality of hot rolled steel sheets. Based on Principal Component Analysis (PCA) and Gradient Lifting Decision Tree (GBDT) methods, this paper takes the tensile strength as the research object and constructs a prediction model for the mechanical properties of hot rolled strip steel. Through principal component analysis of characteristic data, 28 variables were reduced into 8 new indicators to be used for GBDT regression analysis. 2489 pieces of data were divided into a training set and a test set at a ratio of 7:3, to be used in the training set to build a regression model, and get a root mean square error of 16.7393. The data in the test set was used to predict the tensile strength value, with the root mean square error reaching 18.2650.

Purpose of the work – to study of the processes that determine the interaction of non-metallic inclusions and the steel matrix during steel rolling. Methods. The behavior of inclusions was studied during hot rolling of steels 08Yu, 08T, 08kp, NB-57, 08GSYUTF in the temperature range of 1 200...900 °C and cold rolling with degrees of deformation of 35...75 %. The study of hot slipping along the boundaries of the inclusion − matrix was observed during high-temperature (900...1 200 °C) deformation by stretching in a vacuum on the IMASH-5S installation with a gripper movement speed of 1 680 mm/min. According to the study of slipping, steel samples were stretched in a vacuum at temperatures of 25...900 °С on the IMASH-5S installation with a gripper movement speed of 2 000 mm/min. On the surface of the samples, using the PMT-3 device, reference points were applied near the 0° and 90° inclusion poles on both sides of the inclusion − matrix boundary. Research methods are given in works [10; 11]. Identification of inclusions was carried out by metallographic (Neophot-31), petrographic and micro-X-ray spectral (MS-46 Cameca) methods. Results. It is shown that during plastic deformation, there is an interaction between non-metallic inclusions and the steel matrix, which determines their joint plastic shape change and is associated with the development of competing processes at the inclusion − matrix interphase boundaries: interphase friction and slipping (hot or cold depending on the deformation temperature). The mechanisms of these processes are determined depending on the deformation conditions and the level of plasticity of non-metallic inclusions and the steel matrix. Scientific novelty. The peculiarities of interphase friction and hot and cold slipping along the inclusion − matrix interphase boundaries of steel under different conditions of plastic deformation have been established. It is shown that the mechanisms of each of these processes depend on the temperature regime of deformation, the level of plasticity of the inclusions and the steel matrix, as well as on the structure of the inclusion − matrix boundaries, which determines the possibilities of movement and interaction of interfacial defects. It is shown that the specified processes determine the level of plasticity of the inclusion − matrix boundaries and significantly affect the nature of the change in shape of the inclusions and their redistribution in the steel matrix during steel rolling, which inevitably affects the technological plasticity of steels. Practical significance. The use of the results obtained will make it possible to develop technologies for producing steels with regulated types of nonmetallic inclusions, which will significantly increase their technological characteristics, as well as prevent the formation of various kinds of defects during the processing of steels by pressure of products.

Rolls of longproduct rolling mills, as an expendable working tool of the rolling technological operation, make up a significant share of redistribution costs and significantly affect the economic efficiency of the manufacturing process. The importance of rolls is manifested in the organization of their production at specialized enterprises, the presence of rolling menage in the workshops of metallurgical enterprises, the development and introduction of new rolling rolls materials. Therefore, the tasks of analyzing the available roll materials and their properties, choosing the optimal set of properties for the conditions of a certain state become quite actual.
 The purpose of the work is to review rolled materials and analyze the properties of rolls used in modern long-product mills. Such an analysis was performed for steel and cast-iron rolls, the use of which is most common on mills for the production of simple profiles in the form of bars and rods.
 Based on the analysis of the latest research and publications, the stages of the development of rolled materials in retrospect, the main indicators of the mechanical, technological and operational properties of the rolls have been determined. The main types of cast iron and steel rolling materials offered by leading manufacturers of rolling rolls are also established. For these groups of roll materials, an analysis of their mechanical properties, such as hardness, tensile strength, and bending strength, was performed.
 Based on the results of the analysis, a significant improvement in the mechanical and operational properties of modern rolled materials was noted. This is achieved due to alloying, improvement of their manufacturing technologies, specialized types of heat treatment aimed at forming a certain structure and properties. Conditional blurring of boundaries between cast iron and steel rolls is also established. For example, iron rolls with a ferrite structure and spheroidal graphite and graphitized steel rolls are used, which provide approximately the same mechanical strength, gripping ability and wear resistance.
 Modern rolled materials are characterized by the expansion of controlled property indicators. This applies both to the components of the chemical composition and to indicators of mechanical properties. In particular, the leading manufacturers of rolled rolls include the bending strength limit, which is 1.5 to 2 times higher than the strength limit from tensile tests, among the mandatory indicators.
 In the calculations of the rolls, the fulfillment of their strength conditions should be checked by the allowable stresses determined beyond the bending strength limit, as an indicator of the properties, which to a greater extent corresponds to the load conditions of the rolls.
 An objective assessment of the performance of the rolls according to the strength conditions can be obtained only when determining the allowable stresses based on the actual values of the properties provided by the manufacturer of the rolls, and not according to the range of values recommended in the literature.
 The results of the conducted analysis can be used for the justified selection of rolling materials, improving the control of their properties, obtaining objective assessments of their performance, increasing the efficiency of the rolling farm and technical and economic indicators of production processes.

Purpose. Justification of technical solutions as to the reduction of the amplitude and reduction of the dynamic change duration in the tension of the rolling stock at the exit of the output cage when moving to winding a new layer to an acceptable level in terms of its effect on the resulting profile of the rolled product through the control of the rotation frequency of an output cage. Methodology. The conducted research was based on a complex model of the process of rolled steel winding with a Garrett-type winder and the tension of rolled steel in the area of the exit cage-winder. To control the actual amount of tension at the output cage exit, it is suggested to use the amount of free deflection of the rolled steel directly behind the cage. The research was carried out by simulating the process of rolled steel winding according to the basic control scheme and control schemes that predict the influence on both drives, i.e. the winder drive and the output cage drive according to the actual value of tension, in various combinations with further analysis and comparison of the obtained results. Findings. It was established that the correction for the deviation of the actual rolling tension in the finishing cage-winder area from the specified value of the winding current of the winder electric drive does not eliminate rolling tension when switching to the next layer winding and the oscillating form of the transition process, which are characteristic of the basic rolling winding scheme. In turn, the correction of the rotation frequency of the output cage rolls drive reduces the amplitude of the roll tension jerk by almost half with a simultaneous reduction in the time of the transition process and readjustment when switching to a new layer winding. Originality. It has been shown for the first time that the introduction of the roll tension control circuit by correcting the high-speed rolling mode of the output cage ensures minimization of dynamic changes in the rolled steel tension when switching to a new layer winding and reduces the probability of local tightening of rolled steel profile. Practical value. The use of the described technical solutions in the control system of the section of rolled products winding of the small-grade wire mill DSDS 250/150-6 PJSC ArcelorMittal Kryvyi Rih ensures the improvement of the commercial properties of the winding of rolled products produced on the rolling mill.

A rolling bearing plays a key role in the gearbox of the cold rolling mill transmission system. As a result, the degradation and failure of bearings can lead to unplanned shutdowns of the entire rolling mill system. Since on-site cold rolling mills work usually in non-steady lubrication rolling conditions originating form variations of multiple parameters, the uncertainty affecting bearing performance in a cold rolling mill transmission system increases, making it more difficult to assess health status and predict the remaining service life of bearings, Therefore, by establishing a coupling model describing the relationship for the rolling mill and normal /faulty gearboxes under non steady rolling conditions, quantitatively studies the influence of various rolling parameters of a rolling mill on the fatigue service life of bearings in the gearbox of the rolling mill transmission system, and verify the effectiveness of linear cumulative damage theory for bearing fatigue service life through experiments and on-site bearing vibration data. The results indicate that as the thickness of the strip steel inlet, lubricant viscosity, and rolling speed increase, or the thickness of the strip steel outlet and rolling roll radius decrease, the service life of bearings gradually decreases. As the fluctuation amplitude of various rolling parameters in the cold rolling mill increases, the service life of bearings in the gearbox of the rolling mill transmission system gradually shortens. Moreover, when the rolling parameter value or fluctuation amplitude increases to a specific values, the remaining service life of bearings will sharply decrease. Under the same rolling conditions, the service life of bearings in gearboxes with faults decreases more significantly than that in normal gearboxes.

Oil-in-water emulsions (O/W-emulsions) are generally used to lubricate the cold rolling process of low-carbon steel. Besides the obvious advantages of efficient lubrication and cooling of the process, there are also some disadvantages mainly related to emulsion bath maintenance, subsequent production steps and waste disposal. In some application areas, Oil Free Lubricants (OFL’s) have shown to be at least equally effective in decreasing friction and wear as conventional lubricants, while resulting in benefits related to waste disposal. In 2018 a project (acronym ‘RollOilFree’) was started with funding from the Research Fund for Coal and Steel (RFCS). The objective of this project was to develop an OFL as a lubricant for the cold rolling process of low-carbon steel and hot rolling of aluminium. A cold rolling lubricant can be evaluated based on many criteria; for some criteria the OFL even outperformed the oil-based emulsion, but it was found that for some rolling conditions the coefficient of friction with the OFL was still too high. In September 2023 a follow-up project, “Transfer of aqueous oil free lubricants into steel cold rolling practice” (acronym ‘RollOilFreeII’) has begun, also in the RFCS-framework. This article briefly recapitulates the findings in the RollOilFree-project and describes the objectives and benefits of the RollOilFreeII-project. Furthermore, the main activities in the project will be discussed.

Rolling force and temperature field are important parameters in the hot rolling process of plate steel. Most researchers use ANSYS/LS-DYNA and MSC.Marc to simulate the hot rolling process, however, software DEFORM-3D is not used widely in this field. Therefore, in this study, the commercially available finite element analysis software DEFORM-3D is used to simulate the distribution of rolling force, stress-effective, strain-effective and temperature field during the hot rolling process of plate steel with the size of 0.220m×2.070m×1.904m. Both the simulated rolling force and temperature of the multi-pass are compared with the measured results. It is shown that the simulated values by the finite element method are approximate to the measured values in the hot rolling of plate steel. So the simulation can provide an important reference and optimization to make rolling process and parameters in steel factory.

Considering the problems and details of modeling process of cold rolling, it was constructed a theoretical model of deformation area based on a set of equations, which were practical testing. The model is based on cold-rolled numerical solution of differential equations of forces equilibrium in the deformation area by Karman. In the model there are included modules for calculating strip temperature and strip gage at the exit from the stand, considering elastic recovery of the strip. For adaptation of the equations to the specific conditions of cold rolling of HSLA steels in the continuous five stand mill 2030 and assess the deviation of calculated data from the actual, a procedure of correction for hardening curve of rolled steel has been developed. The model allows defining the energy-power parameters of rolling: average unit rolling force, the full force of rolling, rolling moment, rolling force, an average temperature of strip at the inlet and outlet of each of the mill stands, steel hardening curve when rolling. The model is implemented as software using object-oriented approach in the language of C++ Builder.

Ultrasonic rolling of 42CrMo Steel: Simulation-Based process optimization for high-efficiency and sustainable manufacturing☆

Purpose The purpose of this study is to focus on numerical simulation investigations of deformation analysis of asymmetric break-down rolling of a hollow steel, which seriously affects the service life of the final product. Design/methodology/approach The 3D rigid-plastic thermo-mechanical coupled finite element method (FEM) for a large strain was used to analyze metal deformation in the deformation zone for asymmetric rolling with different roller diameters. Findings The distribution of stress, strain and dimension accuracy for different diameters was obtained. The results show that the additional shear strain which is different from the normal compression deformation is generated in an asymmetric rolling process. The higher the ratio between upper and lower diameters, the greater the additional shear deformation. Originality/value Asymmetric rolling is an important factor affecting the dimensional accuracy of the hollow steel. This study can provide a theoretical basis for developing a reasonable rolling process of the hollow steel.

The issues of the activities of the Council of the Research and Production Center of OJSC “BSW – Management Company of the Holding “BMK” – NAS of Belarus aimed at solving the problems of the enterprises of the holding, the proposals of the heads of “BSW”, scientific institutions of the NAS of Belarus and universities of the country to assist in their solution are highlighted. The issues of scientific and technical activity, equipping the enterprise with modern equipment are considered. The results of the work on the harmonization of European and republican standards are presented, as a result of which the harmonized international standards STB ISO 683‑1‑2020, STB ISO 683‑2‑2020, STB ISO 683‑3‑2020 were developed for the first time, passed all approvals and entered into force in the Republic of Belarus, a new improved metallurgical technology for smelting, out‑of‑furnace processing and rolling of steels corresponding to international standards was developed. The environmental problems of the enterprises of the BMK holding related to the disposal of waste generated at the enterprise were discussed. Methods and ways of their processing and utilization are considered.

ABSTRACTReported is a relationship between a profile edge cracking during hot rolling of AISI D2 tool steel and material and processing parameters. Several months of observation of industrial hot rolling was done for neural network analysis and complemented with equilibrium thermodynamics calculations and laboratory hot deformation tests. Industrial results, in general, show that for the same chemical composition, hot rolling yield decreases with an increased profile aspect ratio. Cr content is significant for the soaking and strongly correlated with a hot workability at upper and lower limits of the hot working temperature range. Laboratory hot compression tests were employed to determine the optimal soaking temperature and to study hot workability to expand safe hot working temperature window.

Microstructure evolution simulation in hot rolled DP600 steel during gas metal arc welding

The water consumption intensity of steel production through BF-BOF technology was decomposed by an innovative process-based water-accounting model, i.e., water-balance model. One ton of steel product was chosen to be the functional unit. The system boundary of the case study included the production processes of coking, sintering, iron making, steel making, continuous casting and rolling. The results showed that the water consumption intensity of steel production was 3.969t/t in this case. The water consumption of evaporation, solidification and wastewater were 2.373t, 0.013t and 1.583t, accounting for 59.79%, 0.33% and 39.88% of the total water consumption, respectively. Steel rolling is the largest contributor to water consumption, and the amount of water consumption is 1.523t, accounting for 38.37% of the total water consumption; followed by coking process and continuous casting process, the amounts of which are 0.814t (20.50%) and 0.634t (15.97%), respectively. This finding can push the utilization of advanced technologies to save water resource in steel industry.

Based on the investigation and study of the topography and composition of the buildups, combined with production process of silicon steel, the major causes of forming buildups of carbon sleeve are analyzed from the factors such as the quality of carbon sleeve, furnace atmosphere, dew point, adjusting steel roll, intermediate steel roll, running speed of carbon sleeve and so forth. Meanwhile, some countermeasures to reduce the formation of the buildups are put forward.