EVRAZ (Canada)

Vacuum degassing (VD) is a critical refining step in electric arc furnace (EAF) steelmaking for producing clean steel with reduced nitrogen and hydrogen content. This study develops an Effective Equilibrium Reaction Zone (EERZ) model focused on denitrogenation (de-N) by simulating interfacial reactions at the bubble–steel interface (Z1). The model incorporates key process parameters such as argon flow rate, vacuum pressure, and initial nitrogen and sulfur concentrations. A robust empirical correlation was established between de-N efficiency and the mass of Z1, reducing prediction time from a day to under a minute. Additionally, the model was further improved by incorporating a dynamic surface exposure zone (Z_eye) to account for transient ladle eye effects on nitrogen removal under deep vacuum (<10 torr), validated using synchronized plant trials and Python-based video analysis. The integrated approach—combining thermodynamic-kinetic modeling, plant validation, and image-based diagnostics—provides a robust framework for optimizing VD control and enhancing nitrogen removal control in EAF-based steelmaking.

The article touches upon the problem of inconsistencies and insufficient accuracy of quantitative methods applied in analyzing mergers and acquisitions. The authors point out that the criteria for the effectiveness of the concluded deals used by the majority of researchers do not conform to the real factors which are not taken into consideration by companies’ top managers when making decisions about a deal. This results in the gap between theoretical developments and their practical application and also limits the implementation of scientific results in practice. The authors study and identify the main disadvantages of the most common analysis methods: Cumulative Abnormal Returns, or CARs, Buy and Hold Abnormal Returns, or BHAR, and also, they suggest hypotheses of medium-term profitability and long-term payback illustrating the criteria of predicting the success of mergers and acquisitions from the viewpoint of management. The authors have developed new approaches to statistical analysis of the market of mergers and acquisitions that allow to identify the deals the results of which differ significantly from the average in one direction or another. Further development and empirical testing of the suggested approaches can provide for the introduction of new techniques of evaluation of effectiveness of mergers and acquisitions, as well as for creation of sectoral and universal recommendations for top managers of the buyer companies on their basis.

The hydrogen induced cracking (HIC) resistance of four (4) L80 casing steels, with different nominal compositions and processing conditions, was determined using the NACE TM0284 HIC test. Microstructural and inclusion characterization of each steel was undertaken using optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The morphology (equivalent diameter, aspect ratio and major length) of inclusions over identical analysis regions were measured for each steel. In total, >15,000 inclusions were characterized. Non-linear models correlating inclusion morphology with the measured values of CLR (crack length ratio) and CTR (crack thickness ratio) were developed. The models show that both CLR and CTR are complex functions of the diameter (equivalent) of oxide-based inclusions and the major length of the manganese sulfide (MnS) stringers. The models show that oxides <10 μm in diameter were found to have negligible effect on HIC resistance (CLR) while oxides >20 μm exhibited a significant and escalating negative impact on HIC resistance comparable to long (>50 μm) MnS stringers.

Приведены результаты комплексного исследования химического и вещественного составов, а также макроструктуры образцов огнеупоров после службы в горне доменной печи с полезным объемом 2200 м3 в течение 14 лет. Комплексным методом определено содержание углерода в исследуемых образцах. Установлено образование цинксодержащих фаз как на месте оксидных огнеупоров керамического стакана, так и в углеродистой футеровке фурменной зоны и горна. Износ огнеупоров в горне имеет сложный, преимущественно термохимический механизм и малую скорость из-за формирования гарнисажа, содержащего тугоплавкие соединения.

It is known that the value of impact toughness is sensitive to the geometric accuracy of manufacturing, the quality of the surface and concentrator of samples for impact bending. These parameters have a particularly strong influence on samples made of high-carbon materials. At present, the main regulatory document for the manufacture of samples for impact bending is GOST 9454‒78, which does not regulate the method of applying concentrators. Currently, methods of drawing, milling and electroerosion processing are used to apply the concentrator. The issue of the influence of processing methods on the magnitude of impact strength, in particular rail steel, has not been fully studied. To study the effect of electroerosion processing on impact toughness value we made specimens of P65 rail of DT350 category from 76ХФ steel of current EVRAZ ZSMK production using CNC milling machine and electroerosion processing. It has been established that the decrease in the values of impact strength of samples made using electroerosive machining was due to martensite released during local melting of the metal and non-ferrous metals (Cu and Zn) released during processing. During the operation of the electroerosion processing machine, an uneven surface was formed when the arc locally knocked out “holes”, which serve as additional stress concentrators during impact bending tests. The application of the concentrator by a milling machine leads to the formation of a deformed layer up to 80 µm deep, which is not a stress concentrator and does not reduce the impact strength of the rail steel. As part of a further study, it is planned to investigate the effect of the application of the concentrator by the pulling method on the value of the impact toughness.

In process of shaped profiles experimental rolling, it is often necessary to make adjustments to new roll pass design to ensure their physical filling, control between gaps in the values of real broadenings and reductions. In order to reduce number of possible adjustments in roll pass design process and mastering new profiles, the task of developing a model for calculating roll passes becomes actual. A model for calculating roll pass design for rolling railway rails presented. This model based on roll pass design for rolling R65 rails. The regression equations of deformation logarithmic degree were derived using example of two pre-finishing and finishing roll passes, which were used to calculate UIC60E1 rail roll pass design. A high degree of convergence of the geometry of the calculated and operating roll pass has been established. The maximum deviations from geometry of existing roll pass and calculated ones according to proposed method did not exceed 1-2 mm on each of them. It was shown that the developed model calculates exact roll pass geometry, which can be loaded into the program of a processing machine. The proposed calculation methodology can be used at roll pass design of shaped profiles of the same type of different profile sizes of the same mill, resulting in significant reduction of roll pass designed development time and number of adjustments.

Dependence of plastic deformation resistance of chromiumalloyed rail steels on the thermomechanical parameters of deformation (degree, speed, and temperature of deformation) and chemical composition of the steels under consideration was obtained by hot mechanical tests for torsion and compression. According to the obtained data, an increase in rate and a decrease in deformation temperature cause an increase in resistance to plastic deformation. Effect of relative deformation on resistance to plastic deformation is nonlinear with an expressed maximum at deformation degree of the order of 0.25. Analysis of influence of chemical composition of 76KhF, 76KhSF and 90KhAF rail steels and their resistance to plastic deformation was carried out using methods of multiple regression analysis. It has shown that increasing of content of carbon, manganese, vanadium, nitrogen, sulfur and phosphorus in the actual range of changes in their concentration leads to an increase in their plastic deformation resistance. Mechanism of this effect was revealed. Approximation of the obtained data allowed us to determine interval of changes in deformation resistance when chemical composition varies within the actual range of changes in elements content. Value of specified interval was up to 19 % of the absolute value of deformation resistance. When varying content of chemical elements in the interval specified in state standard for production of railway rails, value of deformation resistance interval was up to 30 %. Checking adequacy of the obtained dependences was performed by oscillographing the stands drives engines of rail mill of JSC “EVRAZ ZSMK” when rolling billets of different chemical composition. This checking made it possible to confirm the revealed patterns.

Very few studies have been conducted concerning fatigue in steel line pipe and fewer using full-scale testing. Further, at the time of this study, no research on full-scale testing was available in open literature regarding fatigue behavior of line pipe with longitudinal cracks, despite being considered more critical than the line pipe with cracks oriented in the circumferential direction. In the current research work, fatigue crack growth was investigated in NPS 20, API 5L X-70 grade, electrical resistance welding (ERW) straight-seam steel line pipes in the base metal and at the weld seam for various orientations. It was found that there was no significant difference between fatigue crack growth in the base metal and at the weld seam for the tested stress ratio. Increasing the angle of inclination of the crack with respect to the weld line was found to decrease the rate of fatigue crack growth due to a decrease in the mode I stress component. Finally, it was observed that despite the difference in fatigue crack growth rates, the crack aspect ratios were nearly identical for all cracks at the same crack depth.