During hot rolling, the coexistence of backward slip and forward slip regions within the deformation zone causes periodic reversal of the frictional shear direction acting on the work roll surface. However, the influence of the alternating shear induced by slip transition on wear damage evolution has not been adequately considered, resulting in an incomplete understanding of work roll wear behavior under actual hot rolling conditions. In this study, the wear damage evolution of hot rolling work roll was investigated under conditions considering the alternating shear effect associated with slip transition. The results show that slip transition leads to higher and more fluctuating friction coefficients, accompanied by more severe local spallation, debris accumulation, and ploughing damage. The oxide layer formed under alternating shear exhibits lower stability and is more susceptible to cracking and spallation. Continuous disruption of the oxide layer promotes the generation of oxide fragments and wear debris, which subsequently act as third body abrasives during sliding, aggravating ploughing damage and abrasive wear. In addition, pronounced grain refinement and increased local misorientation are observed in the near surface region after wear under hot rolling conditions, indicating substantial plastic deformation and strain accumulation beneath the worn surface. These microstructural evolution features reflect the continuous deformation of the near surface material during wear and correspond well with regions exhibiting local damage. Therefore, the alternating shear caused by slip transition should be considered when evaluating wear damage evolution of hot rolling work rolls. The findings provide further insight into the wear mechanisms of work rolls under hot rolling conditions and offer guidance for wear assessment and service life prediction.

Solid-state recycling (SSR) of aluminium machining chips offers an alternative to conventional remelting, avoiding the material losses associated with oxidation while enabling direct consolidation into semi-finished products. However, the relationship between deformation, interfacial evolution, and mechanical response remains not fully understood, particularly in rolling-based processes. In this study, AA6005A chips were consolidated by cold compaction followed by direct hot rolling at 400 °C without prolonged pre-rolling homogenisation. The effect of rolling reduction (70–95%) was investigated in terms of microstructural evolution, interfacial consolidation, and mechanical behaviour in both the as-produced and T6 conditions. Results reveal a non-monotonic relationship between rolling reduction and mechanical performance. At intermediate reductions (~80%), localised strain release leads to a pronounced softening of the as-produced material; this condition records the lowest as-produced yield strength, yet recovers to among the highest values after T6 treatment, indicating that the as-produced and T6 responses are governed by different factors. In the T6 condition, peak tensile properties are achieved at 85% reduction despite incomplete interfacial consolidation, as evidenced by persistent delamination on the fracture surfaces. At 90%, sufficient oxide fragmentation suppresses continuous interfacial failure paths, resulting in predominantly cohesive fracture in both conditions and representing the optimal balance between interfacial integrity and structural performance. At higher reduction (95%), excessive deformation leads to grain coarsening and increased sensitivity to residual interfacial defects, resulting in a reduction in mechanical performance. These findings demonstrate that increasing deformation does not monotonically improve consolidation, but rather defines a processing window governed by the interplay between oxide fragmentation, microstructural evolution, and matrix strengthening.

The key to model development lies in unifying the recrystallization behavior throughout multi-stage hot deformation processes. However, this integration has been hindered by three primary challenges: (1) the lack of a consistent criterion for the onset of dynamic recrystallization (DRX) during repeated deformation; (2) the insufficient consideration of the influence of DRX states on static recrystallization (SRX) mechanisms; and (3) the unclear treatment of recrystallization state transitions during successive deformation stages. To address these issues, this study introduces essential modifications to the internal state variable (ISV) model and extends its applicability to multi-stage hot deformation. Specifically, the critical dislocation density is employed as the criterion for DRX initiation, with a simplified method proposed for its determination. Furthermore, a SRX incubation fraction is incorporated to account for the influence of DRX states on static softening mechanisms. Additionally, a method is proposed to evaluate changes in the recrystallization fraction during repeated deformation by comparing the residual and critical dislocation densities, capturing the effects of recrystallized grain hardening and DRX recurrence. The predictive ability and underlying assumptions of the modified model are validated through double-pass hot deformation experiments. Furthermore, the applicability of the model under dynamically changing deformation conditions is verified. Finally, electron backscatter diffraction (EBSD) analysis of microstructural evolution under different inter-pass holding times is employed to elucidate the deformation mechanisms involved. The proposed model offers a theoretical framework for accurately predicting and controlling material states in multi-pass hot deformation processes.

Lightweight steels are an innovative steel grade whose research is very interesting for application in automotive sector. They are featured by high Mn and Al content, high mechanical properties (up to 800MPa of yield strength and up to 55% of elongation at break) and low density (13% lower than conventional stainless steel). Especially because of the application sector, the assessment of these alloys weldability is of outmost importance. Due to the high content chemical elements different criticalities are expected, as Mn evaporation and κ-carbides precipitation. The former may lead to inhomogeneous chemical composition and so different microstructure, mechanical properties and difference response to welding process. The latter is the most studied strengthening method in this class of steel, but it may lead to excessive ductility loss. An austenitic with high Mn lightweight steel alloy has been tested with Laser Beam Welding with different configurations and different material conditions. Microstructure and mechanical properties of the welded joints has been investigated. Solid welded joints were obtained, but significant macro-porosity was observed in the hot rolled material. In the WZ, both a dendritic and columnar microstructure has been observed, while an extremely narrow grain coarsened-HAZ have been detected. In the WZ a limited softening has been observed in the material after solubilization while in the hot rolled one, the difference is more marked. Uniaxial tensile test has highlighted the macro-porosity effect in the HR samples while it has provided good results in the SOL samples.

To investigate the wear behavior of work rolls under hot rolling conditions, an experimental wear-testing apparatus capable of controlling load, slip ratio, cyclic temperature variation, and cooling was developed. The evolution of the friction coefficient and surface damage during rolling was systematically examined, while fractal theory was employed to characterize the evolution of surface morphology. The results reveal that abrasive wear and surface mechanical damage dominate during the initial stage, whereas oxidation-assisted and adhesive wear gradually become more significant with increasing rolling time because of the repeated formation and fracture of oxide layers. The formation of the oxide film may help reduce direct metal-to-metal contact and alleviate material removal. However, repeated cracking and spallation under coupled thermal and mechanical loading progressively weaken its protective effect. Under intensified thermo-mechanical loading, unstable oxide layers tend to undergo severe spallation, which is associated with accelerated surface degradation. A coupled wear model incorporating thermal, mechanical, and oxidation effects was established to describe the wear evolution, and the predicted results show reasonable agreement with the experimental observations. Sensitivity analysis further indicates that the fractal parameters D and G play important roles in wear evolution, while thermal and oxidation-related parameters also affect the wear process through coupled interactions. These findings provide useful insights into the wear evolution of work rolls under hot rolling conditions.

The transition toward low-emission energy systems requires alternative conversion technologies capable of valorizing carbon-rich waste streams. Molten hydroxide direct carbon fuel cells (MH-DCFCs) offer a promising route for efficient energy production from solid biogenic fuels at temperatures below 600 degrees C. However, a systematic understanding of how the physicochemical properties of carbon-rich materials affect the short-term cell performance is necessary. In this work a total of 9 fuels, of which 7 of biogenic origin and 2 of fossil origin, were used. Each fuel was comprehensively investigated by means of morphological, mineralogical, and chemical characterization, further to particle analysis, proximate analysis, and wettability assessment. The electrochemical efficiency of the MH-DCFC for each matrix was evaluated by open-circuit voltage (OCV) and linear sweep voltammetry (LSV) at 450 degrees C. Results demonstrated that fuel reactivity and performance arise from complex interactions between volatile matter (VM), fixed carbon (FC), ash content, and particle morphology. Optimal OCV and power output (maximum value reached 1060 mV and 6.22 mW cm(- 2)) corresponded to fuels with a FC/VM ratio from 1 to 2, moderate ash content (<30 wt%), and elongated, porous particles (aspect ratio of about 0.5 and 33% porosity). Impurities such as KCl and iron oxides further promote electrochemical activity, while SiO2 inhibit it. Comparison with literature data confirms the observed trends and validates the proposed correlations.

Multi-pass hot caliber rolling technology has significant advantages in producing continuous bars, which can be used as structural and connecting parts with essential applications. Simulation is an important tool for reproducing production processes. The simulation model must show the thermal state, microstructure, and hot workability during the bar’s high-temperature deformation process. However, such a multifunctional simulation model has not yet been reported. Here, a finite element simulation system for hot bar rolling is presented. It is based on the DEFORM-3D software and has been further developed. The most distinctive feature of the proposed simulation system is the integration of a material model that combines constitutive prediction with hot workability prediction. The constitutive model is formulated within an internal state variable framework, enabling the coupled prediction of microstructural evolution and stress response during multi-pass hot deformation. The hot workability prediction model is established based on a backpropagation neural network. By incorporating the microstructural state and deformation conditions as input variables, the model enables dynamic evaluation of hot workability throughout the deformation process. Based on the embedding of the material model, the simulation model can realize the coupled simulation of temperature, deformation, microstructure, and hot workability. Subsequently, the model is validated and applied based on an actual hot bar rolling production line. The simulation successfully predicts the surface cracks in rolled bars and provides insights into the underlying mechanisms of crack formation. The analysis indicates that the primary cause of cracking is the mismatch between the groove geometry and the workpiece geometry, which leads to localized deformation of the corner metal and a sharp temperature drop. Based on this understanding, a matching relationship between the groove geometry and the workpiece geometry is proposed, and the groove structure is optimized accordingly. After optimization, the surface quality pass rate of the rolled bars improved significantly, increasing from approximately 50.7% to about 95.3%. The simulation system can be applied to the hot bar rolling process and other multi-pass hot forming technologies. This is important for optimizing the production process and improving product quality.

The selection of a suitable binder is crucial to ensure efficient powder agglomeration and high mechanical stability of briquettes. In ironmaking and steelmaking, binders must have low silica, low ash, high environmental sustainability, and compatibility with furnace lining and slag. Gelatinized corn starch has shown good performance with several residues (e.g., jarosite, red mud, mill scale), but it has not provided consistent results when used with integrated steel-plant by-products. This study investigated the possibility of replacing corn starch with Arabic gum, analyzing briquettes produced from basic oxygen furnace dust combined with two reducing agents: blast furnace sludge (BFS) and secondary dust (SD). Arabic gum improved impact resistance index of BFScontaining agglomerates reaching IRI of 1000 (125 with starch), due to better particle arrangement and densification. The resulting lower porosity (34.3 % Vs 39.3 %) enhanced contact between carbon and iron oxides, raising the reduction degree to 90 % (86 % with starch). Moreover, the denser microstructure limited the swelling phenomenon observed in starch-bound briquettes during thermal treatment. In contrast, the use of SD as the reducing agent resulted in a coarser particle size, leading to a heterogeneous distribution during the mixing process with Arabic gum. This corresponded to a decrease in mechanical stability, with the briquettes surviving 5 drops compared to 10 with starch. Despite this drawback, the degree of reduction remained largely unaffected at 1200 degrees C.

Steelmaking produces large quantities of iron-rich by-products and their recycling improves resource efficiency and reduces waste generation. This work investigates the potential for utilizing mill scale to produce self-reducing briquettes assessing the effectiveness of recycled Arabic gum as a sustainable binder compared to conventional starch. The briquettes were produced by combining the mill scale with different reducing agents: olive pomace biochar pyrolyzed at 750 (OP750) and 350 °C (OP350), and cupola furnace dust (CFD). By using Arabic gum instead of starch, an improved resistance to impact was observed for each mixture (1000 for OP750 and CFD versus 767 and 191, respectively). Recycled Arabic gum, also, limited the swelling of each mixture and promoted the sintering of the briquettes. On the contrary, the starch favored an increase in volume (maximum 153.62%) until 1200 °C. Furthermore, the Arabic gum enhanced the reduction capacity of the mixture while preventing chemical or morphological variations in the reduction products and leading to an increase of up to 9.06% in the degree of metallization with OP350. Overall, most the results obtained using Recycled Arabic gum exceeded the industrial benchmark, confirming the feasibility of its usage as a substitute for starch in self-reducing briquettes.

This study aims to evaluate the direct natural wet CO 2 absorption potential of steelmaking slag, with a specific focus on the behavior of black and white slag, respectively, collected after the steel production by electric arc furnace and molten steel refining in a ladle furnace. Slag contains significant amounts of calcium and magnesium compounds capable of reacting with atmospheric CO 2 through carbonation, forming stable carbonates and thereby enabling permanent carbon sequestration. Representative samples of black and white slag were monitored to assess their physicochemical properties, mineral composition, and carbonation behavior under natural environmental conditions over time. The investigation seeks to characterize and quantify the tendency and rate of CO 2 uptake for each slag type, highlighting differences in carbonation efficiency. Preliminary findings contribute to understanding the role of steel slag as potential carbon sinks within the steel industry, supporting sustainability goals. Furthermore, the study discusses the main factors influencing carbonation, such as particle size, exposure time, and ambient conditions, thereby providing insights into slag management optimization and the parallel enhancement of CO 2 sequestration during slag-yard stockpiling. This research represents a step forward in incorporating natural carbonation processes of steelmaking by-products into carbon accounting frameworks and promoting their beneficial reuse in climate change mitigation strategies.

For ferrous foundries, sustainability is becoming an essential goal to preserve their competitiveness in producing cast iron. Among the possibilities applicable to the iron and steel industry, the charging of alternative iron sources inside the furnaces could represent an effective approach. Following the paradigms of recycling metallurgical residues and the valorization of non-fossil carbon sources, this study examined the use of mill scale–biochar agglomerates as a complementary iron source for producing gray cast iron in induction furnaces. The effect of the agglomerates co-charging (7 wt.

As a critical intermediate stage in the continuous casting and rolling process for bar production, the heating quality of a walking beam reheating furnace significantly affects billet shaping and the performance of the finished bars. To address issues such as uneven billet temperature distribution during heating, which leads to non-uniform deformation resistance in the rolling process, causing bending deformation, excessive thermal stress, and the initiation of microcracks and propagation of inherited casting cracks, this study uses 20CrNiMoA steel billets as the research object. The temperature field distribution inside the walking beam reheating furnace was simulated with ABAQUS finite element software. The accuracy of the simulation results was verified through ‘black box’ experiments, which demonstrated that the simulation precision meets the standards required for industrial applications. On this basis, the study systematically investigated the effects of temperature and time parameter settings in different heating zones of the furnace on billet temperature distribution and stress evolution. The results show that increasing the charging temperature improves temperature distribution and peak stress during the preheating stage, while lower furnace temperatures during the preheating phase reduce excessive thermal stress, and optimal furnace settings in heating zone I and II enhance heating efficiency and uniformity. The findings provide theoretical foundations and data support for optimizing on-site production heating process parameters and improving billet heating quality.

With the aim of finding new non-fossil carbon sources to decrease the environmental impact of metallurgical processes, this research, conducted as part of the MICS (Made in Italy Circular and Sustainable) project, explores on a laboratory scale the production of biochar from four woody matrices, wood chips, wood pallets, wood pellets, and olive pomace. The biomasses were characterized before and after pyrolysis (process temperature 350 °C and 750 °C) by proximate analysis, activation energy, chemical and mineralogical composition, and the properties compared with those of fossil carbon sources currently used in the metallurgical industry (e.g., coke and graphite). The results represent a starting point for the definitive introduction of upgraded wood waste into metallurgical processes. Specifically, wood pellets pyrolyzed at 750 °C possessed the closest properties to graphite and metallurgical coke (total carbon: 93.51 wt.

The production of Electric Arc Furnace (EAF) slag is 150-180 kg per ton of steel, making its recycling essential for the steelmaking process’s sustainability. Despite favourable mechanical properties as its good abrasion resistance, environmental challenges, such as the leaching of harmful elements (e.g., Cr, V, Ba and Mo), limit its direct reuse in industries like cement production, road construction and water filtration. The mineralogical composition of the slag is the key to address its leaching behaviour, as the hydration of specific phases (e.g., larnite and brownmillerite) can release these elements. Current regulations demand minimal environmental impact and require precise quantification of slag phases to identify and mitigate the leaching mechanisms. The slag is generally and rapidly characterized by means of X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM), however the quantitative analysis obtained by the Rietveld method is not always reliable because of the presence of preferential orientations common to several phases and the high sensitivity to the imposed background. Therefore, it is necessary to implement a methodology to refine the X-Ray analysis. Selective dissolution of larnite and brownmillerite, dangerous for Ba and Cr leaching, can be used for this purpose. In this work, different quantitative techniques were compared to tune-up the Rietveld analysis. These methods facilitated the accurate determination of critical phases like larnite and brownmillerite. SEM and XRD analyses have intrinsic limitation in quantifying phase contributions. In particular the identification of brownmillerite with XRD is overestimated respect the chemical prediction due to its strong crystallographic orientation al low 2θ angle. Selective chemical dissolution is instead the most reliable technique to quantify the phases, since a previous salicylic acid methanol (SAM) dissolution dissolves all the calcium silicates and a following potash sucrose (KOSH) treatment quantify all the calcium aluminates. The difficulties encountered doing only KOSH were associated to the formation of a viscous gel due to the hydration of silicates. If the dissolution of the brownmillerite was not complete, a second KOSH dissolution is required.

This study presents a scalable and eco-friendly thermo-catalytic methane pyrolysis (TCMP) for producing high-value carbon materials with tailored crystallinity and morphology, aiming to provide a sustainable alternative to conventional carbon materials such as furnace-derived morphology-controlled carbon. A key innovation is the use of stainless steel as both the reactor container and catalyst, utilizing the iron and nickel content to enhance methane decomposition efficiency. This dual function not only simplifies the reactor design but also supports large-scale production, solving the previous limitation of reactor clogging. Moreover, the study pioneers use of CO2 injection as the second novel strategy for in-situ catalyst regeneration. These approaches simplify reactor design, reduce clogging, and improve process sustainability, addressing key limitations in existing TCMP systems. The resulting carbon materials exhibit diverse morphologies, allowing customization for varied industrial applications. Although definitive performance correlations require further study, Sample A displayed a relatively higher graphitization level, while Sample B exhibited more amorphous features, both addressing potential for distinct applications such as conductivity, catalysis, or adsorption depending on specific functionalization and purification. Characterization through Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) confirms the structural adaptability achieved. While elemental traces of Fe, Cr, and Ni are present, they are consistent with catalytic residues and may be acceptable or beneficial in some industrial uses. This work also investigates the interconnection between hydrogen generation and carbon valorization, proposing that the solid carbon byproduct from methane pyrolysis, particularly the low-porosity, partially graphitized material, may serve as a feedstock in metallurgical processing such as ironmaking, where high-carbon-content reductants are essential. In this way, the dual utility of methane decomposition products enhances the overall sustainability and circularity of the TCMP process.

The iron and steel sector is one of the hardest-to-abate sectors from an emission point of view, emitting 3.74 Gt CO2 annually and contributing to 10% of global energy-related greenhouse gas emissions. Hydrogen-based direct reduced iron is one of the options to achieve deep decarbonization of the sector. This study proposes an innovative hydrogen-DRI process integrating a high-temperature solid oxide electrolyzer cell. The main idea is to produce the reducing stream by means of the electrolyzer, while using natural gas only in the bottom part of the furnace to increase the carbon content and cool down the direct reduced iron. Three cases featuring different integration degrees between iron and hydrogen production units are assessed. The high integration level reduces the direct carbon dioxide emission by 96% compared to the reference natural gas fed process. Finally, an off- design analysis is performed to assess the mass and energy balances of the system operating at different loads in response to variable availability of renewable electricity. The results show that the plant can be efficiently used in several off-design configurations, maintaining good product quality while managing the electric consumption and hydrogen production rates.

The Charpy impact toughness of single-phase austenitic Fe-32Mn-0.6C steel was systematically investigated across a wide temperature spectrum from 25 °C to -196 °C using Charpy V-notch impact tests. The material exhibited a remarkable temperature dependence of impact energy, decreasing dramatically from 120 J at ambient temperature (25 °C) to 13 J under cryogenic conditions (-196 °C). Notably, a steep transition in impact energy occurred within the critical temperature window of -100 °C to -150 °C. Microstructural analysis revealed that synergistic effects of high strain rates and low temperatures significantly restrict dislocation slip and multiplication mechanisms, while also suppressing deformation twinning activation. This restricted plasticity accommodation mechanism fundamentally differs from the deformation characteristics reported in conventional low-carbon high-manganese steels and other face-centered cubic (FCC) alloy systems.

This paper is focused on the description of the integrated route for the steel production. The main plants involved in such a route have been treated and the main process steps have been described: sintering of the iron ores, coal treatment to obtain the coke, pig iron production by the blast furnace and its conversion to steel by the basic oxygen furnace. During the description of these plants and processes, the main pollution source have been pointed out. Finally, a synthetic presentation of the plants used for the reduction of the iron ores by natural gas has been performed.

The hot processing map serves as a fundamental tool for evaluating hot workability and optimizing processing parameters. However, the hot processing map establishes a direct relationship between hot workability and deformation conditions, leaving the mechanisms underlying hot workability evolution unclear and limiting the applicability. This paper aims to develop a method for predicting hot workability that comprehensively accounts for the effects of both deformation conditions and microstructural states. Thermal deformation and microstructural characterization are carried out on a low-carbon steel to investigate evolution in hot workability within typical hot working ranges (900-1050 °C, 0.01-10s−1). A neural network model integrated with Shapley additive explanations is then employed to establish the coupling relationships among deformation conditions, microstructural states, and hot workability. Dislocation density and dynamic recrystallization fraction and deformation conditions exert a coupled effect on hot workability. A prediction framework for hot workability is proposed, integrating microstructure states and deformation conditions, and comprising a coupled internal state variable constitutive model and two neural network models. The complex interactions among deformation conditions, microstructure evolution, and hot workability are thoroughly demonstrated under representative conditions. DRX softening and sustained work hardening represent two distinct mechanisms for enhancing hot workability at low and high strain rates, respectively. The proposed predictive framework reveals the coupled relationships among deformation conditions, microstructural state, and hot workability.