Search Results (521)

As the goal of carbon peak and carbon neutrality becomes a global consensus, the circular economy is gradually evolving from an environmental concept to a core lever for national strategy and industrial transformation. To achieve green and low-carbon development, China is accelerating the construction of a circular economy system, particularly in the fields of resource recycling and utilization. Industrial waste heat, a strategically critical supplementary energy resource, performs a pivotal role in advancing the circular economy. Based on an energy technology coupling model, this study assesses the waste heat utilization potential in China and quantitatively measures its impact on energy conservation and carbon reduction. The results show that: (1) The potential of industrial waste heat in China is characterized by an inverted U-shaped trajectory. Over the near-to-medium term, the steel and power industries remain the primary contributors to waste heat utilization potential. (2) Low-grade waste heat represents the majority of utilization potential in China’s industrial sector, mainly from power generation, fuel processing, and steel manufacturing. The model results indicate that the proportion of low temperature waste heat will increase from approximately 66% in 2025 to 83% in 2060. (3) Waste heat utilization significantly influences the energy transition pathway. The findings of this study demonstrate that energy-intensive industries have the potential to reduce primary energy consumption by more than 13%. Moreover, making full use of waste heat could accelerate China’s carbon peaking target to 2028, and reduce peak carbon emissions by an estimated 5.1%. Full article

To reduce CO₂ emissions into the environment, the automotive sector uses microalloyed structural steels coated with electrophoretic paint in various components, such as the chassis, to reduce weight and increase corrosion resistance. AHSSs are coated with electrophoretic paint (E-coat). Still, to improve adhesion, they undergo a pretreatment, such as zinc phosphate or zirconium oxide. This research will analyze the effects and behavior of these coatings during corrosion on a complex-phase (CP) 780 AHSS using different electrochemical techniques, including cyclic potentiodynamic polarization (CPP), electrochemical noise (EN), and electrochemical impedance spectroscopy (EIS). The CP 780 AHSS was immersed in a 3.5 wt. % sodium chloride solution. Results show that AHSS CP 780 presented a mixed corrosion mechanism due to the heterogeneity of the surface of the zinc phosphate and zirconium oxide pretreatments. On the other hand, the samples with an E-coat paint coating and pretreatment (Zn₃(PO₄)₂/E-coat and ZrO₂/E-coat) have the lowest current densities with values of 6.44 × 10⁻¹¹ 1.02 × 10⁻⁹ A/cm² and also do not show a tendency towards localized corrosion or negative hysteresis. Full article

The Turkish steel industry aims to reduce its sectoral carbon dioxide (CO₂) emissions by 55% by 2030, in line with Türkiye’s Paris Agreement commitments and the European Green Deal (EGD), and consistent with the ambition of the European Union’s economy-wide ‘Fit for 55’ emissions-reduction target. Türkiye faces significant challenges in achieving net-zero greenhouse gas (GHG) emissions, particularly as a developing country confronting the impacts of climate change and in the market situation, such as the effects of the ongoing Russia-Ukraine conflict, limited access to affordable raw materials, and rising operational costs. This study serves as a guideline for the Turkish steel sector’s roadmap towards modernization and eventual compliance with net-zero targets. The consideration and integration of new technologies planned for the Turkish steel industry, in both electric arc furnace (EAF) and blast furnace-basic oxygen furnace (BF-BOF) facilities, have been outlined in conjunction with green hydrogen and with Carbon Capture and Storage (CCS) technologies. Four different scenarios were analysed to understand the reduction in CO₂ emissions: (1) In a Business-As-Usual (BAU) scenario without any reduction, (2) 39.9% CO₂ emission reduction with the Moderate scenario, (3) 59.6% reduction with the Advanced scenario, and (4) 82.9% reduction in CO₂ emissions from the Turkish steel sector with the Net-Zero scenario. To quantify the uncertainty in these long-term projections, a Monte Carlo simulation was conducted, generating probabilistic confidence intervals that reinforce the robustness and credibility of the net-zero pathway. The official roadmap for the sector is not available as of today; however, an in-depth discussion with a policy innovation leading to it is the objective of this study. Full article

Steel, a fundamental material in modern industry, is widely used across manufacturing, construction, and energy sectors. Steel surface defects exhibit characteristics such as multiple classes, multi-scale features, small detection targets, and low-contrast backgrounds, making detection difficult. We propose RAC-RTDETR, a lightweight real-time detection algorithm designed for accurately identifying small surface defects on steel. Key improvements include: (1) The ARNet network, combining the ADown module and the RepNCSPELAN4-CAA module with a CAA-based attention mechanism, results in a lighter backbone network with better feature extraction and enhanced small-object detection by integrating contextual information; (2) The novel AIFI-ASMD module, composed of Adaptive Sparse Self-Attention (ASSA), Spatially Enhanced Feedforward Network (SEFN), Multi-Cognitive Visual Adapter (Mona), and Dynamic Tanh (DyT), optimizes feature interactions at different scales, reduces noise interference, and improves spatial awareness and long-range dependency modeling for better detection of multi-scale objects; (3) The Converse2D upsampling module replaces traditional upsampling methods, preserving details and enhancing small-object recognition in low-contrast, sparse feature scenarios. Experimental results on the NEU-DET and GC10-DET datasets show that RAC-RTDETR outperforms baseline models with MAP improvements of 3.56% and 3.47%, a 36.18% reduction in Parameters, a 40.70% decrease in GFLOPs, and a 7.96% increase in FPS. Full article

Central segregation, a typical internal defect in continuous casting slabs, significantly deteriorates the mechanical properties of steel products. However, traditional manual defect evaluation methods rely heavily on experience, are highly subjective and inefficient, making it difficult to meet the quality assessment requirements of today’s high-end steel materials. In this study, an approach which combines an unsupervised image enhancement algorithm and Otsu algorithm analysis was proposed to achieve automatic recognition and quantitative features extracting of central segregation in continuous casting slabs. The challenges posed by insufficient brightness and low contrast in central segregation images were addressed using unsupervised image enhancement algorithms. Following this enhancement, batch objective quantification of the segregation images was conducted through Otsu processing. Comparative experimental results showed that the enhanced images yielded an average Dice Similarity Coefficient of 0.965 for segregation recognition, representing a 38% improvement over unprocessed images, with consistent accuracy gains across complex segregation scenarios. This intelligent detection method eliminates the need for manually labeling a training set, substantially improves the consistency of segregation quantification and reduces the time cost significantly. Consequently, multiple parameters can be employed to quantify segregation characteristics, offering a more comprehensive and precise approach than current simplified rating methods. This advancement holds promise for enhancing quality control in steel processing and advancing Artificial Intelligence-driven technological progress within the metallurgical sector. Full article

The construction sector faces increasing pressure to decarbonize, as embodied emissions from structural materials often dominate the environmental footprint of reinforced concrete (RC) buildings. Although reinforcement ratios are key drivers of structural capacity, their environmental implications under seismic design remain insufficiently quantified. This study investigates the relationship between longitudinal reinforcement ratios and both seismic performance and life-cycle environmental impacts in RC frame buildings. Three code-compliant reinforcement configurations (1%, 3%, and 5%) were analyzed for three- and nine-story structures designed under Eurocode 8. Mechanical performance was evaluated using nonlinear pushover analysis, while embodied impacts were quantified through Life Cycle Impact Assessment (LCIA) using the ReCiPe 2016 midpoint and endpoint methods. Results show that increasing steel content reduces concrete volume and increases lateral capacity, but may significantly decrease ductility and increase environmental burdens. Optimal performance is achieved with moderate reinforcement ratios, which reduce embodied impacts while preserving seismic safety. Furthermore, reducing the amount of concrete while increasing the amount of steel reduces the weight of structures by between 19% (3 stories) and 22% (9 stories), improving their seismic resistance due to the reduction in seismic forces in areas of moderate seismicity. These findings demonstrate that reinforcement selection introduces a measurable trade-off between structural integrity and sustainability, providing designers with quantitative guidance for low- and medium-rise RC buildings in seismic regions. Full article

Stainless steels are widely used across many industrial sectors, including the fabrication of welded structures. The most common methods for joining these materials are arc welding processes. Increasing demands for higher weld quality and process efficiency have led to a growing adoption of laser-based technologies in industry. One of the most frequently applied techniques is hybrid laser–arc welding (HLAW), which combines two heat sources—the laser beam and the electric arc—acting simultaneously. For new, innovative joining technologies, a critical factor in their implementation is their impact on the environment and human health. This article presents the results of a study on the morphology of fumes emitted during the HLAW of X5CrNi18-10 (1.4301) stainless steel. Laser diffraction and scanning electron microscopy were used to characterize the fume morphology. The International Agency for Research on Cancer has classified welding fumes as a carcinogenic agent to humans. The results revealed that more than 20% of particles generated during hybrid welding belong to the most hazardous fraction, as they can penetrate beyond the laryngeal region. These particles exhibit a homogeneous elemental distribution, with the chromium content standing at approximately 20% and nickel nearly 10%. Full article

Construction and demolition (C&D) waste remains a critical challenge in India due to accelerated urbanisation and material-intensive construction practices. This study integrates survey-based assessment with machine learning to identify key causes of C&D waste and recommend targeted minimization strategies. Data were collected from 116 professionals representing junior, middle, and senior management, spanning age groups from 20 to 60+ years, and working across building construction, consultancy, project management, roadworks, bridges, and industrial structures. The majority of respondents (57%) had 6–20 years of experience, ensuring representation from both operational and decision-making roles. The Relative Importance Index (RII) method was applied to rank waste causes and minimization techniques based on industry perceptions. To enhance robustness, Random Forest, Gradient Boosting, and Linear Regression models were tested, with Random Forest performing best (R² = 0.62), providing insights into the relative importance of different strategies. Findings show that human skill and quality control are most critical in reducing waste across concrete, mortar, bricks, steel, and tiles, while proper planning is key for excavated soil and quality sourcing for wood. Recommended strategies include workforce training, strict quality checks, improved planning, and prefabrication. The integration of perception-based analysis with machine learning offers a comprehensive framework for minimising C&D waste, supporting cost reduction and sustainability in construction projects. The major limitation of this study is its reliance on self-reported survey data, which may be influenced by subjectivity and regional bias. Additionally, results may not fully generalize beyond the Indian construction context due to the sample size and sectoral skew. The absence of real-time site data and limited access to integrated waste management systems also restrict predictive accuracy of the machine learning models. Nevertheless, combining industry perception with robust data-driven techniques provides a valuable framework for supporting sustainable construction management. Full article

As a result of welding processes in boron-alloyed martensitic armor steels, unfavorable microstructural changes occur, leading to a significant reduction in the mechanical properties of both the weld metal and the base material. The dendritic structure of the weld metal and the partial tempering in the heat-affected zone contribute to the decreased durability of structural components, thereby deteriorating their performance. This issue is particularly important since such steels are widely used not only in the defense industry but also in the mining, construction, transportation, and metallurgical sectors, where they operate under conditions of intensive abrasive wear. For this reason, the authors attempted to improve the mechanical properties of welded joints of boron-alloyed martensitic armor steel (with a nominal hardness of 500 HBW) through post-weld heat treatment. The welded joint was evaluated based on metallographic examinations using light microscopy and scanning electron microscopy, as well as abrasive wear tests carried out on a T-07 tribotester. The conducted investigations demonstrated that, under loose abrasive conditions (using electrofused alumina), heat treatment increased the wear resistance of the joints by 55% compared to the as-welded condition. The obtained results were compared with selected grades of Hardox steel commonly used in industrial applications. Full article

The construction sector, particularly the production of materials like cement and steel, is a major contributor to global CO₂ emissions, with cement alone responsible for about 8%. Conventional masonry relies heavily on cement, increasing embodied carbon and costs, but standardized data on low-carbon alternatives such as compressed stabilized earth blocks (CSEBs) remain scarce, limiting their adoption in sustainable housing. To support the United Nations Environment Program (UNEP) and the Paris Agreement goals for net-zero embodied carbon in building materials by 2050, this study aims to assess the production and performance of CSEBs as a low carbon alternative to conventional masonry. It specifically addresses the research gap on technical performance and carbon savings, providing new empirical evidence for Ethiopian soils. Soil samples from Kara (east of Addis Ababa) were analyzed for grading, plasticity, and chemical composition. Blocks were produced with Portland pozzolana cement (4–12%) under compaction pressures of 4–10 MPa and tested for compressive strength and water absorption over 56 days. Results show that 6% cement content achieved >2 MPa compressive strength, meeting the structural requirements, while higher cement content and pressure improved strength and reduced absorption. Compared to hollow concrete blocks, CSEBs cut cement use by over 50%, avoiding up to 2 tons of CO₂ per 100 m² of wall. These findings confirm CSEBs as a technically viable and climate-conscious solution for affordable housing and support their integration into sustainable construction practices. Full article

In this paper, the effects of 3D printing parameters on the metallurgical and mechanical properties of 3D-printed 25CrMo4 steel are presented. Using laser-based powder bed fusion of metals (PBF-LB/M), samples were fabricated under varying conditions of laser power, scan speed, and layer thickness. The study examined how variations in volumetric energy density (VED) and linear energy density (LED) influence the material’s performance. The results show a strong correlation between the printing parameters and key properties such as hardness, porosity, bending strength, compressive strength, and tensile strength. Appropriate VED and LED improved density, reduced defects, and enhanced mechanical performance, whereas excessive energy inputs introduced brittleness. These findings support the advancement of additive manufacturing technologies for high-strength steels and broaden their potential applications in the aerospace, automotive, and construction sectors. Full article

Gigapascal ultra-high-strength steel holds significant applications in the energy and military sectors. Such steel is typically produced through quenching and tempering processes. However, during quenching, issues such as excessive internal stress often lead to significant deviations in flatness, thereby reducing product precision. This study adopts an approach integrating theoretical and practical methods to develop a control technology for achieving high flatness in gigapascal ultra-high-strength martensitic steel. Firstly, finite element simulation was employed to establish a temperature-phase transformation-stress coupling model for the quenching process of gigapascal martensitic steel. The study investigated the deformation behavior of steel plates under unilateral cooling, the influence of dynamic martensitic transformation on internal stress, and the effects of plate thickness and water ratio. This revealed how quenching process parameters affect the internal stress and deformation of steel plates. Based on theoretical calculations and considering on-site equipment conditions, industrial production line commissioning was conducted, which significantly reduced the quenching internal stress of gigapascal ultra-high-strength martensitic steel and greatly improved the flatness of the steel plates. The results surpassed those of international companies such as Sweden’s SSAB and other domestic enterprises, achieving an internationally leading level. Full article

This study evaluated locust bean gum (LBG), a polysaccharide thickening agent, as an anti-corrosion active compound against sweet corrosion for N80 carbon steel used in the oil and gas sector. The assessment involved weight loss and electrochemical measurements at different temperatures (e.g., 25 °C and 80 °C) and immersion durations (up to 168 h) in a CO₂-saturated 2 wt.% KCl solution. The electrochemical results showed that LBG effectively inhibited sweet corrosion at both temperatures, and its efficacy increased with its concentration, reaching maximum inhibition efficiency of 84.11% at 25 °C and 55.81% at 80 °C, using 0.3 g L⁻¹ of LBG after 24 h of immersion. At 25 °C, and with 0.3 g L⁻¹ of LBG, the inhibition action of LBG did not change, even after 168 h of immersion (e.g., 83.97%). At 80 °C, LBG showed a good inhibition up to 72 h (e.g., 47.04%), after which LBG had no additional protective effect. This result is attributed to the formation of a FeCO₃ layer that covered the entire metal surface, blocking the adsorption of LBG. Potentiodynamic tests revealed that LBG’s inhibitory effect is of a mixed type. The Temkin adsorption isotherm model accurately described the data, indicating that LBG adsorption involves primarily physical interactions, with some chemical contributions. Activation energy and heat of adsorption calculations support the physical nature of LBG’s adhesion. FTIR analysis confirmed the interaction between LBG and N80 carbon steel, while SEM-EDS provided visual evidence of LBG’s influence on the metal surface. Full article

The anodization of Ti° enables the formation of well-ordered TiO₂ nanotubes, a highly promising nanomaterial with exceptional photochemical properties and potential applications in the energy and environmental sectors. This study addresses the growth of TiO₂ nanotubes on large-scale surfaces applied for photocatalytic processes. The present investigation approaches the scaling up of the reactor for anodizing Ti°-coated flat surfaces and thus connecting the TiO₂-nano-structure with real-world applications. For this, 316 stainless steel sheets were coated with a uniform Ti° layer using the arc cathodic method. The results indicate that the (~3 µm) thick Ti° arc-PVD coatings are well anodized, despite the inherent amount of µm-sized droplets produced during the deposition. The results reported here highlight the effects of the anodization process parameters—voltage, current, and time—on nanotube growth. At 60 V, the nanotubes exhibited a highly uniform cylindrical morphology, homogeneous walls contributing to an ordered, stable, and open nanostructure at large Ti-coated surfaces. The scaling up of the reactor for the controlled anodization process of Ti° coating is addressed. This approach validates Ti°-based PVD coatings at a semi-industrial scale on commercial stainless steel, thus enabling affordable production costs. Lastly, the anodization of Ti° coatings is a viable, scalable manufacturing process for producing photocatalytic nanostructured surfaces. Full article

Alkyd resins (ARs) represent a significant development in synthetic polymers, being among the oldest ones and playing a crucial role in numerous applications, especially within the coating sector. The trend is moving towards replacing non-renewable resources in the production of ARs with bio-based alternatives, with the goal of creating more sustainable binder materials as part of the transition to a bioeconomy. 2,5-Furandicarboxylic acid (FDCA) serves as a promising biomass-derived “building block” to replace non-renewable petroleum-derived aromatic diacids and anhydrides in AR synthesis. Various vegetable oils, including sunflower seed (SFO) and linseed oils (LSO), were utilized along with pentaerythritol (P) and glycerol (G) as polyols. FTIR and ¹H NMR spectroscopies were conducted for the verification of alkyd structures. The synthesized ARs were assessed for their physico-chemical properties, including acid value, hydroxyl value, color, density, and viscosity. The performance of the resulting alkyd coatings, which are crucial for their commercial applications, was examined. Key factors such as drying time, hardness, adhesion, wettability, chemical and corrosion resistance, and UV stability were analyzed. All synthesized FDCA-based alkyd coatings demonstrate outstanding adhesion, good thermal stability up to 220 °C, and barrier properties for steel with |Z|_0.02Hz ~10⁶–10⁷ Ohm cm⁻², which render them suitable for the processing requirements of indoor coating applications. The higher temperature at 50% mass loss (T₅₀) for SFO-P (397 °C) and LSO-P (413 °C) as compared to SFO-G (380 °C) and LSO-G (394 °C) indicated greater resistance to thermal breakdown when pentaerythritol was used as a polyol. Replacing glycerol with pentaerythritol in FDCA-based ARs resulted in a viscosity increase of 1.2–2.4 times and an enhancement in hardness from 2H to 3H. FDCA-based ARs exhibited decreased tack-free time, enhanced thermomechanical properties, and similar hardness as compared to phthalic anhydride-based ARs, underscoring the potential of FDCA as a sustainable alternative to phthalic anhydride in the formulation of ARs, integrating a greater proportion of renewable components for wood coating applications. Full article