Industrial Symbiosis refers to a collaborative approach, including synergies among companies for the transaction of resources, such as materials, energy, water, and by-products, thus resulting in mutual benefits and promoting a Circular Economy approach. Over the past decades, the steel sector was committed to reduce waste production as well as reuse waste and by-products to exploit them as a resource. Significant results in Industrial Symbiosis implementation have been achieved, creating new synergies and networks with other industrial sectors. Nonetheless, a comprehensive analysis of technical and non-technical barriers, that hinder the successful implementation of Industrial Symbiosis within the steel sector, can help implement an integrated and synergic approach encompassing and merging results and experience already achieved. This review paper presents a comprehensive overview of recent studies on the research trends on Industrial Symbiosis, considering drivers and barriers to its implementation, and maps the recent achievements related to the steel sector, by analysing the impact of some significant case studies. For instance, CO 2 valorisation in flue gases and steel slags to produce silicates and carbonates via mineral carbonation and CO 2 capture, re-use and sequestration by industrial symbiosis activities involving the steel and ammonia/urea industries are presented. The literature review based on selected publications allowed tracing the evolution of Industrial Symbiosis over the last few years. The assessment of main lines for research in Industrial Symbiosis allows identifying the challenges for future research. The analysis of implementation of new technologies can help to create new symbiotic networks and further developments and scenarios for the steel industry in a future characterized by material scarcity, decarbonization, and more stringent environmental legislation.
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.
This study investigates the influence of incorporating aluminum fibers, in proportions ranging from 0% to 2.5%, on the mechanical and thermal properties of cement-based mortars. Tests were conducted after 7 and 28 days of curing. Experimental results indicate that a fiber content of 2% yields the highest compressive strength, while a progressive improvement in flexural strength is observed with increasing fiber content, reaching a maximum at the same concentration. Regarding thermal behavior, a significant reduction in thermal conductivity was observed, particularly between 0% and 1.5%, indicating an insulating effect induced by fiber addition. In addition, open porosity, bulk density, and water absorption were characterized in accordance with relevant standards to evaluate the influence of fibers on the mortar’s microstructure. The novelty of this research lies in the application of the two-parameter Weibull statistical model to describe the dispersion of compressive strength measurements, accounting for the heterogeneous nature of the material. These findings provide a deeper understanding of the overall behavior of fiber-reinforced mortars and open new perspectives for optimizing their performance in applications with demanding mechanical and thermal requirements.
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 transition toward a low-carbon energy system requires safe and efficient infrastructure for hydrogen distribution. One of the main challenges is selecting pipeline materials capable of resisting hydrogen embrittlement and sour service conditions. This study evaluates the performance of a high-strength low-alloy (HSLA) steel, grade X46M (7.11 mm thickness), for potential application in hydrogen distribution pipelines and environments containing H2S. The material was produced via Electric Arc Furnace (EAF) and thin slab continuous casting with direct rolling (Arvedi ESP (TM) process), then formed into high-frequency welded (HFW) pipes and subjected to seam annealing. A comprehensive testing program, including chemical and microstructural characterization, tensile and impact tests, and specific evaluations for hydrogen embrittlement and sulfide stress cracking, was implemented in accordance with EIGA guidelines and API 5L PSL2 and ASME B31.12 standards. Hydrogen-related performances were assessed through fracture toughness tests (K-IH) in 100% hydrogen at 80 bar for 1000 h and Slow Strain Rate (SSR) tests under 100% hydrogen. Sour service resistance was verified by Hydrogen Induced Cracking (HIC) and Four-Point Bent Beam (FPBB) tests in NACE Solution A. The results confirmed that the steel under investigation exhibits a homogeneous ferrite-pearlite microstructure, hardness below 250 HV, and mechanical properties meeting API 5L PSL2 requirements. K-IH values exceeded the ASME B31.12 threshold, while SSR tests showed only moderate ductility reduction without brittle fracture. No evidence of HIC or sulfide stress cracking was observed. These findings demonstrate that steel grades produced via the non-conventional EAF + Arvedi ESP (TM) route can be considered suitable for hydrogen distribution and sour service applications, supporting their potential use in future hydrogen pipeline infrastructure
This work explores the replacement of natural gas with hydrogen as the combustion fuel in free-flame continuous heat treatment furnaces for stainless steel strip, focusing on its influence on oxide scale formation and removal in AISI 316L steel. The higher water vapor content of hydrogen combustion atmospheres may alter the oxide scale’s composition, thickness, and adherence, potentially affecting downstream descaling and pickling processes. To assess these effects, both cold- and hot-rolled AISI 316L samples were annealed and oxidized in 100% CH 4 and 100% H 2 combustion atmospheres under three different thermal cycles. The resulting oxide layers were analyzed through SEM, EDX, and GDOES to determine their morphology and chemical composition, followed by comparative evaluation of the descaling behavior and minimum pickling times. Results indicate that annealing in both methane and hydrogen fumes modifies the scale of hot-rolled materials, leading to oxidation and spallation. Hydrogen fumes promote spallation, primarily forming Fe 3 O 4 and Fe 2 O 3 powder, while chromium depletion remains unaffected by the atmosphere. For hot rolled material, annealing in hydrogen fumes tends to reduce or leave the pickling time unchanged and to increase the shot blasting weight loss compared to natural gas. In cold-rolled 316L, oxide thickness increases with temperature and is constantly greater in hydrogen fumes due to water vapor-induced chromium evaporation. Iron oxide clusters observed at high temperatures suggest the beginning of breakaway oxidation, though not fully developed under the tested conditions. Annealing in hydrogen fumes similarly reduces or does not influence the pickling time and does not affect overall weight losses. These findings support the potential of hydrogen as a sustainable fuel alternative without detrimental effects on surface quality or processing efficiency.
This research highlights the critical role of stakeholder engagement in the successful implementation of industrial symbiosis (IS) in the circular economy (CE). Although stakeholder engagement is recognised as a key driver in advancing circular economy models, research in this area is limited. In this paper, we examine four industrial hubs within the context of the IS2H4C project. These hubs are referred to as Hubs for Circularity (H4C) and are located in Spain, the Netherlands, Germany and Turkey. Qualitative interviews with key stakeholders from industry, policy, academia and society were used as the research method. The results show that a stakeholder analysis alone is insufficient for H4Cs. This research proved that active and continuous engagement is necessary, with a regional and local approach. Governance structures at these levels are key to long-term engagement. The results suggest that regulatory frameworks, such as the ReFuelEU Aviation Regulation in the German hub, are the main drivers of stakeholder participation, as well as infrastructure delays. Industrial clusters and companies also play an active role in promoting social acceptance, as do trade unions. However, in order to create a sustainable and inclusive environment involving all categories of stakeholders, including society, academia, industry and politics, it is essential to coordinate local and regional authorities, including universities and research institutes. Key barriers include the high cost of investment and uncertainty surrounding long-term financing, both of which can hinder the scalability of hydrogen technologies and sustainable aviation fuel. All hubs face challenges relating to the complexity and instability of regulations. This undermines stakeholder trust, particularly among investors and private companies. Finally, a shortage of skilled labour and limited public acceptance, particularly with regard to safety and environmental concerns, pose ongoing social and implementation challenges.
This work investigates the thermomechanical and shape memory behavior of TPU 90A in both raw filament form and after 3D printing by fused deposition modeling (FDM). The study systematically explores how key printing parameters such as extrusion temperature, infill density, and infill direction affect material performance. A major contribution of this research is the development of a UMAT subroutine in Abaqus, enabling accurate simulation of TPU 90A's thermomechanical and shape memory responses under varied loads and temperature conditions. Validation with experimental data demonstrates a strong shape memory effect, with shape fixity ratio (Rf) and recovery ratio (Rr) exceeding 98%. The numerical model achieves excellent agreement with experiments, as the simulated Young's modulus (53.97 MPa) closely matches the measured value (55.38 MPa). Optimal mechanical properties were obtained using an extrusion temperature of 230 degrees C, 45 degrees infill orientation, and 100% infill density, effectively balancing strength and efficiency. Practical feasibility was illustrated through the fabrication of a personalized finger orthosis. Stress analysis revealed peak values of 17.76 MPa, confirming adequate rigidity for stabilization in medical applications.
By the end of 2050, the European Union aimed to decrease the carbon footprint (CO and CO2) considerably. It was targeted to achieve 80-95% less than the level of emissions in 1990. Hydrogen, as a clean reducing agent, can eliminate the carbon footprint from the steel industry considerably (up to 95%). However, some factors, such as the endothermic nature of H2 reduction and the thermodynamic resistance of some high-temperature mineral oxides against reduction by H-2, hinder such achievement. Hydrogen plasma smelting reduction (HPSR), as an alternative promising method compared to H-2 and conventional carbon-based reduction methods, has emerged both in the lab and on a pilot plant scale in the current years. The direct reduction of chromite ore by HPSR, containing both Cr2O3 and Fe2O3 (and FeO), enables single-step production of low-carbon ferrochromium or stainless steel. Chromium is the major alloyed element of stainless steel produced mainly through the primary metallurgy methods from chromite ore. The ore contains different mineral oxides in the spinel phases that complicate the reduction process. Therefore, the study of different factors on the reduction of pure Cr2O3 is the first step in evaluating the feasibility of ferrochromium production by HPSR. The plasma state provides enough reactivity and heat via the excited species of hydrogen to overcome the mentioned kinetic (THP = 5000-25000 K) and thermodynamic (Delta G degrees HP <= -1500 kJ/mol) obstacles. In this paper, the in-situ evaluation of reduction degree via hydrogen by optimizing gas flow rate, melting temperature, and activity on pure Cr2O3 and the mixture of it with selective acidic and basic fluxes in different crucibles (structural steel and magnesia-chromite refractory) was studied. Moreover, the required thermodynamic assessments for the experiment were conducted to clarify the feasibility of the reduction process.
The Ti6Al4V alloy is a common choice for biomedical implants due to its biocompatibility and corrosion resistance, though improvements are continually sought for long-term safety and performance. To address this, a hydroxyapatite (HAP), a bioceramic material structurally similar to bone, was utilized as coating agent. To enhance its properties, HAP was blended with chitosan (CS) to create a hydroxyapatite-chitosan (HAP/CS) nanocomposite coating. The Ti6Al4V alloy substrates were uniquely fabricated using laser powder bed fusion (LPBF) to mimic natural bone structure, and the HAP/CS coatings were deposited by electrophoretic deposition (EPD). The phase composition and microstructure were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. A scratch test was performed to evaluate the adhesion strength and durability. The integration of chitosan significantly improved the interfacial bond and cohesion of the coating. Specifically, the 30% CS/HAP coating exhibited the optimal adhesion performance, achieving a total delamination critical load (LC3) of 6.87 +/- 0.34 N, a 28.4% increase compared to the pure HAP coating (5.35 +/- 0.27 N). This study indicates that HAP/CS coatings can ameliorate Ti6Al4V performance and enhance the biocompatibility of implants for biomedical usage.
This study investigates the enhancement of waste low-density polyethylene (WLDPE) properties through the incorporation of mineral fillers, specifically dolomite and calcite. Addressing WLDPE waste is critical for reducing environmental impact, and mineral fillers offer a cost-effective and sustainable solution. WLDPE/dolomite and WLDPE/calcite composites were prepared using a solvent-based method at varying filler contents. X-ray diffraction (XRD) analysis confirmed the presence of calcite and dolomite crystalline phases within the polymer matrix. Fourier transform infrared spectroscopy (FTIR) revealed the persistence of characteristic bands of both resin and fillers, with slight shifts indicating interfacial interactions between polymer functional groups and mineral surfaces. Differential scanning calorimetry (DSC) demonstrated a moderate improvement in thermal stability: the decomposition temperature of neat WLDPE (412 degrees C) increased by 8 degrees C for 5% calcite and by 6 degrees C for 10% dolomite, while beyond 15% filler content, the effect became negligible. These findings suggest that weak interactions, consisting probably of van der Waals forces or hydrogen bonds, contribute to slight structural and thermal enhancements. This approach highlights the potential of mineral fillers to upgrade recycled WLDPE, offering a promising pathway for sustainable plastic waste management.
This study assesses the mechanical properties of four composite materials, including two hybrid composites, produced using the autoclave molding method. Modal analysis shows that carbon fiber reinforced polymer exhibits the highest Young's modulus (91 GPa), while the hybrid carbon/glass and glass/carbon fiber reinforced polymers demonstrate intermediate stiffness, with moduli of 87 GPa and 57.5 GPa, respectively. Glass fiber reinforced polymer presents the lowest Young's modulus, at 28 GPa.The study also examines how cutting parameters-specifically cutting speed, feed per tooth, and width of cut-affect vibration levels during trimming. The results indicate that increasing cutting speed and feed rate leads to higher vibration amplitudes. These parameters also influence surface quality, with measured surface roughness values ranging from 0.45 & micro;m to 0.9 & micro;m. In terms of material comparison, the hybrid composites exhibit vibration behavior and surface finish intermediate between those of carbon-fiber- and glass-fiber-reinforced polymers. The main takeaway is that selecting appropriate cutting parameters is essential to balance surface quality and machining efficiency, particularly for hybrid composite materials.
Wheat straw (WS) shows great potential as a reinforcing material for polylactic acid (PLA) composites. However, at high loading levels, this can lead to fiber embrittlement and poor interfacial adhesion. In this study, wheat straw was modified using a 3% NaOH solution and PLA and maleic anhydride-grafted PLA (MAH) as compatibilizers to evaluate the effect of varying talc-to-starch ratios on the properties of high-content wheat straw composites. SEM analysis indicates that NaOH modification removed impurities and increased fiber surface roughness, improving interfacial compatibility. The tensile strength, flexural strength and impact strength of the NaOH-modified composite were 12.7 MPa, 27.5 MPa and 8.8 kJ/m & sup2;, respectively, 3.2, 2.45 and 2.38 times that of the unmodified composite. Upon incorporation of talc and starch into this formulation, talc alone markedly enhanced the tensile and flexural strengths of the composite, whereas starch alone improved the impact strength. When talc and starch were co-added at a 1:1 ratio, the composite exhibited the most balanced overall mechanical properties. However, when the talc-to-starch ratio was adjusted to 2:1 or 1:2, the mechanical properties of the composite deteriorated markedly. Comparative analysis indicated that the composite comprising 60% NaOH-modified wheat straw, 32% PLA, 7% MAH, and 1% talc exhibited the optimal overall reinforcement effect, achieving a tensile strength of 15.83 MPa, a flexural strength of 31.34 MPa, and an impact strength of 8.23 kJ/m & sup2;.
This paper presents a simple, efficient, and a green, eco-friendly method to synthesize ZnO nanoparticles through Artichoke and Cardoon waste as biological reducing agents. This strategy minimizes the utilization of environmentally dangerous chemicals in the production process. The ZnO nanoparticles were characterized through UV-Vis spectroscopy, FTIR, XRD, and SEM-EDX, confirming their formation and properties. Furthermore, the photocatalytic efficiency of the synthesized ZnO nanoparticles using a green approach against dyes was successfully demonstrated.
This study investigates the wear resistance of two different surface techniques applied to Hardox 400 Steel: the direct deposition of chromium nitride (CrN) via physical vapor deposition (PVD), and a duplex strategy where CrN is deposited onto a surface that has first undergone gas carburizing. Our research focuses on the impact of these two treatments on improving the scratch resistance of Hardox 400 steel. A scratch test was performed to evaluate the adhesion of the thin films by identifying the critical loads corresponding to the onset of each damage mode. Adhesion analysis was supplemented with optical microscopy observations. The duplex treatment improves load distribution and reduces coating cracking. Consequently, higher critical load values were achieved. The PVD and duplex-treated layers exhibited Lc1 values of approximately 6 N and 10 N, respectively, which are significantly higher than that of untreated steel (3.17 N), indicating improved resistance to cohesive cracking and enhanced coating adhesion. The best coating adhesion was achieved with the duplex treatment. Multipass scratch tests were conducted to quantify the coefficient of friction, wear volumes, and energy dissipation. The results provided valuable insights into the tribological behavior of the different treatments. It was demonstrated that the duplex system significantly reduces the coefficient of friction by nearly a factor of 3, and decreases the wear volume to approximately 1.56 & times;106 mu m3 for the duplex CrN coated sample and 9.53 & times;106 mu m3 for the untreated Hardox 400, under an applied load of 20 N.
Fused deposition modeling is a widely adopted additive manufacturing technique due to its affordability and ability to produce complex geometries. However, selecting the fused deposition modeling process parameters to achieve multi-objective responses remains challenging due to their conflicting behaviors. For this purpose, a novel hybrid framework integrating Grey Relational Analysis and Particle Swarm Optimization, guided by Taguchi method, focuses on improving the tensile strength of FDM 3D polylactic acid materials. Raster angle, layer height, nozzle temperature, print speed, and bed temperature were considered as the input parameters. A statistically validated regression model accurately predicts Grey Relational Grades, enabling efficient multi-objective optimization of FDM process parameters. Statistical analysis was performed to identify the significance and influence of key input parameters. This study finds better prediction accuracy with Taguchi-Grey Relational Analysis-Particle Swarm Optimization. This method improved the Grey Relational Grade by 37% over Taguchi-Grey Relational Analysis prediction and 35.8% compared to the initial optimal parameters derived from experimental parameters. The maximum ultimate tensile strength and percentage elongation were achieved under the following conditions: a raster angle of 0 degrees, nozzle temperature of 210 degrees C, layer height of 0.1 mm, print speed of 60 mm/s, and bed temperature of 60 degrees C. The optimal parameters of the hybrid Taguchi-GRA-PSO method, validated against experimental data, achieved experimentally 74.5% of the polylactic acid filament's ultimate tensile strength and 82.5% of the percentage elongation. The effects of input parameters on macrostructure, microstructure, and dynamic mechanical analysis of 3D-printed PLA material are investigated. The results of this study provide practical insights for industries employing FDM 3D printing processes with polylactic acid materials.
The European steel sector is committed to improve sustainability of the whole steel production chain, from decarbonisation of major upstream processes up to all downstream operations, including rolling. In particular, in the cold rolling process, oil-in-water emulsions are usually applied to lubricate the cold rolling process of low-Carbon steel. Such emulsions present some drawbacks mainly related to emulsion bath maintenance, subsequent production stages and waste disposal. Past research works showed that in some application areas, Oil Free Lubricants (OFL) show lubricant properties that are comparable to conventional lubricants, while providing significant environmental benefits. These lubricants are formulated as aqueous dispersions of Polyalkylene Glycols (PAG), a water-soluble synthetic polymer base, combined with various additives for lubrication enhancement, corrosion protection, and oil rejection. The project entitled "Transfer of aqueous oil free lubricants into steel cold rolling practice" (Ref. RollOilFree II - G.A. No 101112433) aims at developing an Oil-Free Lubricant for the cold rolling process of low-Carbon steel for applications in the automotive and packaging sectors by assessing its performance in industrial conditions. To this aim, the project combines tests at laboratory scale and simulations with trials in an industrial pilot cold rolling mill and, finally, field trials at industrial scale. Results demonstrate that OFL01 and OFL02 represent the most promising formulations as substitutes for commercial lubricants.The paper overviews the work undertaken in the first 18 months of the project, including laboratory investigations and part of the pilot trials.
