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  Analysis of Technological Regimes of Open-Die Forging with Model Development for Digital Systems of Metallurgical Production

  Kukhar, V. V.

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  Balalayeva, E.

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  Khliestov, H.

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  Khliestova, O.

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  Mazuru, S.

  (Politehnica University of Bucharest, 2026)

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  Contemporary metallurgy requires the efficient production of large-scale components by open-die forging. The paper analyzes the influence of technological parameters (relative bite infeed and relative reduction per pass) on the kinematic (relative elongation) and energy-force (reduced force and reduced work) characteristics of cogging in combined dies. FEM simulations (LS-DYNA) were used for data generation. Based on this data, analytical and high-fidelity AI surrogate models were developed. It is established that both parameters have a monotonic effect on the metrics: narrower infeed maximizes elongation, and reduction determines the absolute load level. The resulting models are intended for embedding in digital twins and automated forging schedule optimization systems.

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  Identification of Early Degradation Mechanisms in Zinc Coating on Cold Formed Steel Sections Through Analysis of the Production–Storage Chain

  Kukhar, V. V.

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  Malii, Kh. V.

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  Mazuru, S. G.

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  Hrudkina, N. S.

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  Butenko, E. O.

  (Springer, 2026)

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  Cold-formed steel hollow sections (CFS) with hot-dip galvanized coatings, such as DX51D+Z140, are widely used in window and façade systems, particularly under accelerated reconstruction and infrastructure recovery conditions. However, premature degradation of zinc coatings, even when products comply with EN 10346 requirements, raises concerns regarding their long-term corrosion resistance and service life. The study investigates early-stage degradation mechanisms of galvanized coatings through a comprehensive analysis of the production–storage chain. Experimental research included coating thickness measurements using electromagnetic and gravimetric methods, chemical analysis of surface contamination, and evaluation of manufacturing history. Test specimens were extracted both from galvanized strip blanks and finished cold-formed steel sections. Chloride, sulphate, and chromate residues were determined using ISO-standardized procedures. The results demonstrated that coating thickness variability and the presence of chlorides, iron oxides, and other contaminants are associated with small bending radii, excessive pressure of forming rolls, and the absence of post-forming passivation treatment. It was established that compliance with nominal Z140 coating requirements alone does not guarantee protection against early white rust formation or undercoating corrosion. A structured risk map was developed to identify root causes of degradation associated with coating non-uniformity, microcrack formation, and surface contamination. The study highlights the necessity of integrated control over technological and logistics operations, including optimization of forming parameters, mandatory passivation treatment, and ventilated packaging systems. Implementation of these measures is essential for ensuring reliable corrosion protection and long-term durability of cold-formed galvanized steel sections.

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  Comparison of Electricity Consumption in the Obsolete and Modern Steelmaking Process: IOSP+BF+OHF vs Midrex+EAF

  Kukhar, V. V.

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  Tymoshenko, D. O.

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  Volovnenko, I. V.

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  Kurpe, O. G.

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  Pashynskyi, V. V.

  (IEEE, 2024)

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  The paper emphasizes the urgent need for Ukraine's metallurgy sector, particularly at PJSC "Zaporizhstal", to replace outdated technologies with modern, sustainable steel production methods as part of the global green transition. The research involved field measurements, data processing, and comparative analysis of electricity consumption in two steelmaking routes: (I) iron ore sintering process (IOSP) with aspiration system + blast furnace (BF) + open-hearth furnace (OHF), and (II) Midrex direct reduction process + electric arc furnace (EAF). The results showed significant differences in specific electricity consumption among the investigated processes. The EAF demonstrated the highest electricity demand at approximately 340 kWh/t, followed by the Midrex process at 85 kWh/t. Electricity consumption of the sintering plant reached about 33 kWh/t, whereas the blast furnace and open-hearth furnace required only about 3.3 and 4 kWh/t, respectively. The study confirms that the traditional route "IOSP + BF + OHF" generates substantially higher CO₂ emissions than the modern "Midrex + EAF" process. Despite higher electricity consumption, Midrex technology and EAF steelmaking provide significant environmental benefits due to reduced carbon emissions and increased flexibility in steel scrap recycling. The obtained results indicate that the implementation of direct reduction technologies combined with electric arc furnaces is a key pathway toward environmentally sustainable and energy-efficient steel production.

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  Energy implications of switching to surfactant-modified concentrate in iron ore pellet induration

  Kukhar, V. V.

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  Chuprinov, Ye. V.

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  Navolniev, I. Yu.

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  Belan, E.

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  Кухар, В. В.

  (Trans Tech Publications Ltd, 2026)

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  The article investigates energy consumption during the drying stage of iron ore pellets, a critical process in ensuring energy efficiency in mining and metallurgical production. Particular attention is given to the influence of charge material moisture content and the application of surfactants (SAS) on the specific consumption of energy resources, namely electricity and natural gas. Industrial trials were conducted at one of the leading mining and processing enterprises in the Kryvyi Rih region, focusing on the transition from the baseline (in-house) concentrate to raw material from another regional enterprise, pre-treated with non-ionic SAS. It was determined that the increased dispersity and hydrophilicity of the new raw material concentrate requires additional moistening of the charge, significantly affecting thermal regimes and energy expenditures during drying. Based on collected experimental data, regression models were developed to quantitatively predict the specific consumption of electricity and gas as a function of technological parameters. The primary factors influencing energy consumption were identified as the moisture content of the charge and the daily throughput of the drying unit. An increase in specific electricity consumption by 17.73% and natural gas consumption by 33.25% was recorded, accompanied by a simultaneous reduction in productivity by 9.55%. The findings are relevant for specialists in energy management, electrical engineering, and thermal analysis in metallurgy, particularly in the development of strategies for optimizing energy consumption under industrial conditions.

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  Technological and chemical drivers of zinc coating degradation in DX51D+Z140 cold-formed steel sections

  Kukhar, V. V.

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  Kostryzhev, A.

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  Dykha, O.

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  Makovkin, O.

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  Kuziev, I.

  (MDPI, 2026)

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  This study investigates the technological and chemical causes of early zinc-coating degradation on cold-formed steel sections produced from DX51D+Z140 galvanized coils. Commercially manufactured products exhibiting early corrosion symptoms were used in this study. The entire processing route, which included strip preparation, cold rolling, hot-dip galvanizing, passivation, multi-roll forming, storage, and transportation to customers, was analyzed with respect to the residual surface chemistry and process-related deviations that affect the coating integrity. Thirty-three specimens were examined using electromagnetic measurements of coating thickness. Statistical analysis based on the Cochran’s and Fisher’s criteria confirmed that the increased variability in zinc coating thickness is associated with a higher susceptibility to localized corrosion. Surface and chemical analysis revealed chloride contamination on the outer surface, absence of detectable Cr(VI) residues indicative of insufficient passivation, iron oxide inclusions beneath the zinc coating originating from the strip preparation, traces of organic emulsion residues impairing wetting and adhesion, and micro-defects related to deformation during roll forming. Early zinc coating degradation was shown to result from the cumulative action of multiple technological (surface damage during rolling, variation in the coating thickness) and environmental (moisture during storage and transportation) parameters. On the basis of the obtained results, a methodology was proposed to prevent steel product corrosion in industrial conditions.

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