ArcelorMittal (Poland)

Rising energy prices, especially in Europe, make it necessary to look for cost reductions wherever possible. It also concerns the industry and hot rolling processes. One of the ideas of reducing costs is to use a roll gap lubrication (RGL) system. Lubrication makes it possible to reduce the forces needed for the materials processing, which directly translates into lower power consumption, but also makes it possible to extend the service life of the working rolls. The authors associated with Krakow Hot Rolling Mill, as a part of their work related to improving the production process of HSLA-type steel, also took into account the possibility of analyzing the subject of roll gap lubrication. This paper is a review of interesting papers concerning research on this topic over the past years. The authors also included in this paper a section on what the RGL system looks like on the AMP HSM in Krakow itself. This paper is a prelude to considering possible modifications to the RGL system.

The study analyzed two selected representative HSLA steels rolled at the Krakow branch of ArcelorMittal Poland S.A. The aim of the analysis was to determine the effect of parameters such as strain and cooling rate on the onset temperature of the transformation from austenite to ferrite. Dilatometric tests were carried out, followed by strain dilatometry. The cooling rate was varied and its relationship with the temperature of the beginning of austenite to ferrite transformation (Ar3) was determined. In the second part of the study, the subject literature was analyzed to find out how quickly the Ar3 temperature could be calculated. The available equations for calculating the Ar3 temperature were checked. However, the results of the calculations were not consistent enough to use these equations in the actual process. Therefore, the authors decided to develop their own equation – the proposed solution allows the calculation of the Ar3 temperature for the two selected HSLA steels mentioned above with an accuracy of several degrees and a correlation of more than 90%.

Abstract This article presents the results of tests on heat-treated R350HT grade rails, which were manufactured on a railhead heat treatment line installed in the heavy section mill of the AMP Branch in Dabrowa Gornicza. The research article presents an analysis of the chemical composition of the tested rails and their basic mechanical properties. It also discusses in detail the fatigue testing procedure performed in accordance with the qualification tests specified for rails in the EN13674-1 standard and the DBS 918 254-1 technical specifications. Microstructure analysis, including pearlite morphology assessment, and macrostructure evaluation results are presented. Results of determining the stress intensity factor, fatigue crack growth rate, fatigue strength, and determination of vertical and horizontal fatigue strength using the staircase method for R350HT steel grade rails are also presented. The requirements for modern heat-treated rails are also discussed, and key rail property parameters that determine their operational properties are identified.

The efficiency of the hot metal pretreatment process plays a very important role in achieving high-quality and low-cost advanced steel. From macromixing phenomena obtained by numerical modeling and physical experiments to compound interaction databases from industry trials, the Authors compared fundamental relationships from the literature with their own laboratory results and plant data. A simple numerical model based on the LES turbulence approach was well-validated by water modeling. Hence for a 300-ton ladle, the mixing time and mixing power were predicted. Finally, the mass transfer controlled rate was calculated based on a computational fluid dynamics model and thermodynamic model, which indicated results limitations. Moreover, from the industry data, it was found that the rate constant of the desulfurization process varies within a wide range, affecting the efficiency of the sulphur removal degree from values 0.6 to 0.98.

The aim of the research in the hot metal desulfurization process is to create a mathematical model that will include both kinetic and thermodynamic aspects of the process.This is intended to increase the accuracy of predicting and obtaining the level of sulfur content in the hot metal, as well as to optimize process costs.By physically modeling the phenomenon of mixing the metal bath, it was possible to determine the influence of the method of supplying the desulfurization agent on the time of complete mixing of the metal bath.This made it possible to determine how the reactants are distributed in metal bath, which influenced further stages of research.By applying the theory of elementary reactors and enriching it with thermodynamic equilibrium calculations using Thermodynamic Equilibrium Software (TES), it will be possible to model the change in sulfur content during the desulfurization process in individual elementary reactors.This approach to the problem will allow the use of a solution that will enable accurate tracking of the sulfur removal process from the metal bath in a given time step.Such use of knowledge in the field of process kinetics and thermodynamic aspects may lead to even better control of the hot metal desulfurization process.

The paper presents a summary of research on the possibility of influencing the state of residual stresses in railway rails by changing the pass design of vertical and horizontal straightener rollers and optimising their distribution on the rail perimeter. The presented results are devoted to the influence of profiled rollers on the level of residual stresses. A wide range of theoretical considerations were carried out based on the use of the finite element method using the commercial Forge software package. In order to verify the results of the theoretical considerations most reliably, a series of “in situ” experiments were conducted in industrial conditions on an existing production line. The tests were carried out on 120 meters long 60E1 railway rails. A significant reduction in the level of residual stresses compared to the standard requirements was achieved.

The aim of the article is to present the remarkable changes in architecture that took place in the 20th century. They can easily be called a revolution regarding the architectural form and the color scheme. Progress was being made through the development of reinforced concrete production methods. In the German Empire (Deutsches Kaiserreich), this material quickly found applications in more and more interesting solutions in architectural structures. In Wrocław (formerly Breslau), then located in the eastern German Empire, exceptional architectural works were realized before and after the First World War using new technology. In 1913, an unusual building was erected—the Centennial Hall, designed by Max Berg (inscribed on the UNESCO World Heritage List in 2006). Berg’s work was inspired by the works of both Hans Poelzig and Bruno Taut. On the one hand, it was a delight with the new material (the Upper Silesian Tower at the exhibition in Poznań, designed by H. Poelzig) and, on the other hand, with the colorful architecture of light and glass by B. Taut (a glass pavilion at the Werkbund exhibition in Cologne). Max Berg left the concrete in an almost “pure” form, not hiding the texture of the formwork under the plaster layer. However, stratigraphic studies of paint coatings and archival inquiries reveal a new face of this building. The research was carried out as part of the CMP (Conservation Management Plan—prepared by the authors of the article, among others) grant from The Getty Foundation Keeping It Modern program. According to the source materials, the architect intended to leave the exposed concrete outside of the building, while the interior was to be decorated with painting, stained glass, and sculpture. The stratigraphic tests showed that the external walls were covered with a translucent yellowish color coating. Thus, the Centennial Hall shows a different face of reinforced concrete architecture.

This paper presents the microstructural changes and mechanical properties of carbide-free bainitic steel subjected to various heat treatment processes and compares these results with similarly treated ferritic–pearlitic steel. A key feature of the investigated steel, which is common among others described in the literature, is that the Si content in the developed steel was >1 wt.% to avoid carbide precipitation in the retained austenite during the bainitic transformation. The phase identification before and after various heat treatment conditions was carried out based on microstructural observations and x-ray diffraction. Hardness measurements and tensile tests were conducted to determine the mechanical properties of the investigated materials. In addition, following the tensile tests, the fracture surfaces of both types of steels were analyzed. Changing the bainitic transformation temperature generated distinct volume fractions of retained austenite and different values of mechanical strength properties. The mechanical properties of the examined steels were strongly influenced by the volume fractions and morphological features of the microstructural constituents. It is worth noting that the bainitic steel was characterized by a high ultimate tensile strength (1250 MPa) combined with a total elongation of 18% after austenitizing and continuous cooling. The chemical composition of the bainitic steel was designed to obtain the optimal microstructure and mechanical properties after hot deformation followed by natural cooling in still air. Extensive tests using isothermal transformation to bainite were conducted to understand the relationships between transformation temperature and the resulting microstructures, mechanical properties, and fracture characteristics. The isothermal transformation tests indicated that the optimal relationship between the sample strength and total elongation was obtained after bainitic treatment at 400 °C. However, it should be noted that the mechanical properties and total elongation of the bainitic steel after continuous cooling differed little from the condition after isothermal transformation at 400 °C.