Search Results (9)

The surface quality of hot-rolled steel products derived from recycled materials is critically impacted by oxide scale formation and adhesion, a behavior significantly influenced by residual silicon (Si) and the processing atmosphere. This study addresses a key research gap by thoroughly investigating the combined effect of water vapor content (10% to 30%) and residual Si content (across various slab types) on scale formation and adhesion, with a direct focus on process optimization to minimize surface defects. Crucially, this research introduces a novel quantitative assessment utilizing a macro-tensile test. This innovative method provides accurate mechanical scale adhesion energy data (measured in J/m²) directly applicable to hot-rolled recycled steel, a technique previously underexplored for this challenging material system. Results reveal that increasing water vapor concentrations significantly accelerate the formation of thicker and more defective oxide scales, thereby directly diminishing scale adhesion strength substantially across tested conditions. Conversely, steel with higher residual Si consistently maintained significantly higher scale adhesion energy than low-Si steel under similar steam conditions. Based on these quantitative findings, this study proposes a specific two-factor strategy for industrial application, strictly minimizing residual Si content while maintaining the furnace water vapor concentration at an intermediate level (approximately 20%). This strategy is shown to optimize scale formation conditions, facilitating efficient scale removal. Such results are crucial for optimizing hot-rolling parameters in recycled steel production, enabling enhanced surface quality and promoting sustainable manufacturing practices by providing a reliable quantitative metric (adhesion energy) for industrial quality control. Full article

In the context of the digital and sustainable transformation of building projects, the integrated approach of Building Information Modeling (BIM) and life-cycle assessment (LCA) has been widely studied. Recent advancements in such integrated modeling processes and techniques have not yet provided reliable and robust decision-making capabilities for designers to intuitively choose between material alternatives. This study develops a new design framework that integrates BIM, LCA, and multi-criteria decision-making (MCDM) algorithms to facilitate sustainable design processes in building projects. A case study using a single-family housing project in the British Columbia province of Canada was implemented to test the designs to demonstrate the effectiveness of the proposed integrated framework, including a three-way comparison of design scenarios—conventional hot-roll steel, recycled steel, and timber. The results indicate a significant performance improvement with the adoption of recycled structural steel materials, surpassing conventional steel designs and demonstrating a similar performance to that of timber designs. The study underscores the importance of informed decision-making in material selection, driven by the quantitative analysis of digital designs and multi-criteria evaluation (e.g., social carbon cost). This integrated framework offers a valuable tool for designers, engineers, and builders to achieve sustainability when designing building projects through the systematic and rapid comparison of environmental performance. Full article

In modern cold rolling mills in the steel industry, iron oxide powder is produced as a by-product when used pickling agents are recycled. Further processing of these iron oxide powders could enable the production of iron powder for various applications in powder metallurgy. For this purpose, a new process route with an eco-friendly hydrogen reduction treatment was developed. The process is able to manufacture a variety of iron particles through minor process adaptations. It was possible to manufacture spherical iron particles with high flowability. The flowability was measured by a Revolution Powder Analyzer, and an avalanche angle of 47.7° of the iron particles was determined. In addition, the bulk density measurements of the processed iron particles collective achieved values of 3.58 g/cm³, and a spherical morphology could be observed by SEM analysis. The achieved properties of the iron particles show high potential for applications where high flowability is required, e.g., additive manufacturing, thermal spray and hot isostatic pressing. By adjusting the process conditions of the developed process, irregular iron particles could also be manufactured from the same iron oxide powder with a very high specific surface of 1640 cm²/g and a low bulk density of 1.23 g/cm³. Therefore, the property profile is suitable as a friction powder metallurgy material. In summary, the developed process in combination with the iron oxide powder from steel production offers a cost-efficient and sustainable alternative to conventional iron powders for additive manufacturing and friction applications. Full article

This study investigated the structural behavior of a beam–slab member fabricated using a steel C-Purlins beam carrying a profile steel sheet slab covered by a dry board sheet filled with recycled aggregate concrete, called a CBPDS member. This concept was developed to reduce the cost and self-weight of the composite beam–slab system; it replaces the hot-rolled steel I-beam with a steel C-Purlins section, which is easier to fabricate and weighs less. For this purpose, six full-scale CBPDS specimens were tested under four-point static bending. This study investigated the effect of using double C-Purlins beams face-to-face as connected or separated sections and the effect of using concrete material that contains different recycled aggregates to replace raw aggregates. Test results confirmed that using double C-Purlins beams with a face-to-face configuration achieved better concrete confinement behavior than a separate configuration did; specifically, a higher bending capacity and ductility index by about +10.7% and +15.7%, respectively. Generally, the overall bending behavior of the tested specimens was not significantly affected when the infill concrete’s raw aggregates were replaced with 50% and 100% recycled aggregates; however, their bending capacities were reduced, at −8.0% and −11.6%, respectively, compared to the control specimen (0% recycled aggregates). Furthermore, a new theoretical model developed during this study to predict the nominal bending strength of the suggested CBPDS member showed acceptable mean value (0.970) and standard deviation (3.6%) compared with the corresponding test results. Full article

Currently, it is common to use steel poles for applications in livestock and agriculture. In this work, finite element analysis of five hot rolling passes for the manufacture of farm poles using 1075 carbon steels from recycled railway material was developed. The steel industry in Mexico imports products from other countries or from companies specialized in metallurgy at an excessive cost. To be more competitive and save costs, companies seek the reutilization of existing resources such as the railway 1075 steel, which has good mechanical properties. SFTC DEFORM-3D software was used to model five hot rolling passes considering a variable cross section railway profile. The effect of rolling speed and temperature were considered to analyze flow behavior. Rolling loads were also determined. Full article

The aim of this paper is to investigate the flexural performance of a new steel–concrete composite beam system, which is required to carry higher loads when applied in flooring systems with less self-weight and cost compared with conventional composite beams. This new composite member is prepared by filling a single cold-formed steel C-section with concrete material that has varied lightweight-recycled aggregates. In addition, varied stiffening scenarios are suggested to improve the composite behavior of this member, since these cold-formed C-sections are of a slender cross-section and more likely to buckle and twist under high bending loads than those of hot-rolled C-sections. The influence of using four different lightweight-recycled aggregates that combine together in the infill concrete material was investigated. These recycled aggregates are recycled concrete aggregate (RCA), expanded polystyrene (EPS) beads, crumb rubber aggregates (CRA) and fine glass aggregates (FGA). For this purpose, 14 samples of cold-formed galvanized steel C-purlin were filled with concrete material (containing 0 to 100% recycled aggregates) which are experimentally tested under pure bending load, and 1 additional sample was tested without the filling material. Further numerical models were prepared and analyzed using finite element analysis software to investigate the effects of additional parameters that were not experimentally examined. Generally, the results confirm that filling the C-sections with concrete material that contains varied percentages of recycled aggregates offer significantly improved the flexural stiffness, bending capacity, and ductility performances. For example, using infill concrete materials with 0% and 100% recycled aggregate replacement increased the bending capacity of hollow C-section by about 11.4 and 8.6 times, respectively. Furthermore, stiffening of the concrete-filled C-sections with steel strips or screw connectors eventually improved the composite behavior of the specimens which led to an increase in their bending capacities accordingly, and this improvement enhanced more with an increased number of these strips and connectors. Full article

This study investigated the use of self-compacting concrete (SCC) made with recycled coarse aggregates (RCAs), which represents a trend of producing environment-friendly concrete, integrated with hot-rolled steel sections by means of headed stud shear connectors in composite structures. Therefore, thirty-six push-out test specimens were examined to assess the shear strength and behavior of the headed stud connectors embedded in RCA-SCC, with the concrete compressive strength, stud diameter, and RCA ratio as the main variables. Four ratios of RCAs ranging from 0 to 60% were used to produce concrete with three different compressive strengths (25, 33, and 40 MPa) for each one. It was found that the use of SCC with RCAs had a negative effect on the shear strength of headed stud connectors. This negative effect could be reduced by increasing the concrete compressive strength and/or the stud diameter. Similarly, a reduction in the shear stiffness of the tested specimens was inversely proportional to the RCA ratio, while the ultimate slip was directly proportional to the RCA ratio. An evaluation of the test results was made by comparing them with those determined by Eurocode 4 and AASHTO LRFD. Full article

Three charges of scrap-based, Ti-stabilized, Cr-Ni-Mo austenitic stainless steel in the form of hot-rolled steel plates were characterized. Based on automated metallographic analyses of representative microstructures, a quality characterization in terms of cleanliness of the hot-rolled steel plates was performed. Elevated contents of impurities, especially Pb, Bi, and oxygen, which affect the hot workability of stainless steels, were detected. The recycled FeTi-cored wire was the main source of the elevated levels of impurities detected in the hot-rolled, Ti-stabilized, stainless-steel plates. Related to this, elevated levels of nonmetallic inclusions (NMIs) and segregations were formed. The three charges were classified based on calculations of the Mahalanobis distance (MD) between the inclusions. The charge with the smallest number of nonmetallic inclusions was set as the reference class. The selection of outlier inclusions based on their MDs and their back-representation into ternary diagrams gave relevant metallurgical information about the abnormalities. The advantage of this technique is that the calculations of the MD and the threshold can be fully automated. Full article

This paper develops a life cycle assessment framework for embodied environmental impacts of building construction systems. The framework is intended to be used early in the design stage to assist decision making in identifying sources of higher embodied impacts and in selecting sustainable design alternatives. The framework covers commonly used building construction systems such as reinforced concrete construction (RCC), hot-rolled steel construction (HRS), and light steel construction (LSC). The system boundary is defined for the framework from cradle-to-grave plus recycling and reuse possibilities. Building Information Modeling (BIM) and life cycle assessment are integrated in the developed framework to evaluate life cycle embodied energy and embodied greenhouse emissions of design options. The life cycle inventory data used to develop the framework were extracted from BIM models for the building material quantities, verified Environmental Product Declarations (EPD) for the material production stage, and the design of construction operations for the construction and end-of-life stages. Application of the developed framework to a case study of a university building revealed the following results. The material production stage had the highest contribution to embodied impacts, reaching about 90%. Compared with the conventional RCC construction system, the HRS construction system had 41% more life cycle embodied energy, while the LSC construction system had 34% less life cycle embodied energy. When each system was credited with the net benefits resulting from possible recycling/reuse beyond building life, the HRS construction system had 10% less life cycle embodied energy, while the LSC construction system had 68% less life cycle embodied energy. Similarly, the HRS construction system had 29% less life cycle greenhouse gas (GHG) emissions, while the LSC construction system had 62% less life cycle GHG emissions. Sustainability assessment results showed that the RCC construction system received zero Leadership in Energy and Environmental Design (LEED) credit points, the HRS construction system received three LEED credit points, while the LSC construction system received five LEED credit points. Full article