Magnitogorsk State Technical University

Objective: to develop a hybrid multi-criteria simulation model for a green supply chain aimed at identifying an optimal combination of green logistics tools. Methods: an analysis of current approaches that integrate multi-criteria decision-making methods with simulation modelling and linear programming was performed. The research explored the application of multi-criteria simulation models to represent the dynamic interactions among green supply chain indicators, material flow parameters, and green logistics tools. Amajor drawback of current integrated models lies in the selection of green logistics instruments: they often omit comprehensive assessments of sustainability indicators specific to each supply chain component and inadequately incorporate constraints arising from logistics resources. Consequently, creating a unified framework that combines multi-criteria analysis, optimization techniques, and simulation modelling is essential to advance the sustainability of green supply chains. Results: a method for integrating multi- criteria analysis, linear programming, and simulation modelling techniques has been proposed. Practical significance: the model developed in this research facilitates multi-criteria decision-making regarding the selection and application of effective green logistics tools within the supply chain.

Abstract Strength and ductility are among the key mechanical properties of metallic materials and are typically characterized by a pronounced inverse relationship. In practice, materials tend to exhibit either high strength or high ductility, while achieving a combination of both properties at a high level is relatively uncommon. This paper investigates the possibility of improving the technological ductility of high-strength and hard-to-deform metals and alloys during metal forming. While the terms “ductility” and “plastic properties” characterize the material itself, the term “technological ductility” here refers to the ability of a material to undergo plastic deformation under specific conditions of stress state, temperature, and strain rate without failure. Low technological ductility of high-strength and hard-to-deform metals and alloys is the cause of many production problems. In particular, it significantly increases the energy consumption and reduces the productivity of rolling processes for such materials in both cold and hot conditions. For example, existing technologies for producing flat cold-rolled products (sheet, strip, ribbon) from high-strength steels (for example, steels such as 70 or alloyed steels such as AISI 420, etc.) with thicknesses less than 1.5 mm consist of two to three or more processing cycles of “cold rolling – intermediate annealing”. The difficulty of processing such steels is due to their low plastic properties, high deformation resistance, and unfavorable stress–strain state. The use of intermediate (recrystallization) annealing at temperatures of 600–710°C in furnaces with a protective atmosphere (nitrogen + hydrogen) for durations from 38 to 44 hours ensures an increase in the plastic properties of work-hardened rolled products. However, significant time costs combined with high consumption of process fuel (natural gas), energy and material resources (electricity, hydrogen, pure nitrogen, technical water) necessitate the development of new, more advanced production technologies for flat cold-rolled products from high-strength steels without the use of costly intermediate annealing operations. The problem of low technological ductility is no less acute in the production of flat hot-rolled products from hard-to-deform steels (for example, steels such as M2, etc.). Existing technologies are based on multi-stage and/or multi-pass hot rolling processes of hard-to-deform steels within a narrow high-temperature range. However, even at high temperatures, such materials are difficult to deform, since the flow stress can reach 350 MPa or more, which corresponds to the strength of many conventional steels in the cold state. This necessitates the development of new and more advanced methods for increasing the technological ductility of hard-to-deform metals and alloys by creating special mechanical deformation schemes that ensure a reduction in the energy–force parameters of processing such materials. The studies were carried out using an industrial-laboratory sheet rolling mill 400 with individually driven work rolls at the Zhilyaev Laboratory of Mechanics of Gradient Nanomaterials. A set of energy-efficient and resource-saving production technological schemes has been developed, ensuring an increase in technological ductility.

Abstract This study investigates the influence of asymmetric hot rolling parameters on the microstructure and mechanical properties of cold-rolled low-carbon steel strip. Particular attention is paid to the role of deformation heterogeneity and cooling conditions in controlling phase composition and strengthening mechanisms. Hot rolling was performed with a relative reduction of 60-70% and a roll speed asymmetry ratio of up to 2, followed by either air cooling or accelerated water cooling. The results of finite element modeling demonstrate that asymmetric rolling provides a more uniform distribution of deformation across the thickness of the strip compared to traditional symmetric rolling. Metallographic analysis revealed that accelerated cooling after asymmetric rolling leads to the formation of a heterogeneous microstructure consisting of fine-grained ferrite (60-70%), martensite (∼30%), and a small fraction of retained austenite. It is shown that the formation of martensite is associated with suppression of diffusional transformations due to rapid cooling, while the presence of retained austenite may contribute to additional strain hardening during subsequent cold deformation. Tensile testing demonstrated that cold-rolled strips produced from asymmetrically rolled material exhibit enhanced strength (950-1050 MPa) while maintaining acceptable ductility (7-8%). The obtained results indicate that the combined application of asymmetric rolling and controlled cooling provides an effective approach for controlling microstructure and achieving an improved balance of strength and ductility in low-carbon steels.

The research aims to reveal the specifics of conceptualizing the flow of time and endowing it with mythological imagery in contemporary video poetry. The study establishes that the phenomenon of time mythologization is one aspect of a broader mythologizing trend within the video poetry genre. The suggestiveness of video poetry is amplified through its reliance on a potent rhythm – the beat of a metronome or the pulse of time – which dictates the rhythm of the human heart. Consequently, a specific chronotope (characterized by the manipulation of time and space and an appeal to sacred mythological time) gains significance as a means of uncovering the fundamental principles of human existence and comprehending a new reality. Themes of history, war, revolution (crisis moments), and the poet’s fate increasingly attract the attention of video poets, who actively utilize archetypal plots and mythologemes in their work. The scientific novelty of the research lies in the application of not only an intermedial approach but also a mythopoetic analysis as a tool for intersemiotic translation within the communicative intersection of poetry, music, and visualization resources. This methodology reveals critical features of modern video art as it seeks new ways to influence the reader/viewer by reimagining reality and creating a new space where a mythological perception of time counters the hopelessness of existential (historical) time.

One of the promising methods for obtaining improved mechanical properties of metals and alloys is the process of dynamic recrystallization. Among the methods of activating and passing this process, one can single out asymmetric rolling. The paper considers the effect of various roll speed asymmetry schemes on the stress-strain state of the metal and the energy-force parameters during section rolling in a two-high stand and in a stand with a four-high pass. Based on numerical modeling in the QForm environment, it is shown that the use of various speed asymmetry options in a four-high pass will increase the value of effective deformation during rolling. Consequently, this will help to reduce the grain size of the deformed metal, which will lead to improved mechanical properties. In addition, the calculation of the energy-force parameters of the rolling process showed the possibility of reducing the rolling force with an increase in the asymmetry coefficient.