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Defect detection is crucial in ensuring the quality of steel products. This paper proposes a novel deep neural network, cascaded adaptive global location network (CAGLNet), for detecting steel surface defects. The main objective of this study is to address the challenges associated with the irregular shape and dense spatial distribution of defects on steel. To achieve this goal, CAGLNet integrates a feature extraction network that combines residual and feature pyramid networks, a cascade adaptive tree-structure region proposal network (CAT-RPN) that eliminates the need for prior knowledge, and a global localisation regression for steel defect detection. This paper evaluates the effectiveness of CAGLNet on the NEU-DET dataset and demonstrates that the proposed model achieves an average accuracy of 85.40% with a fast frames per second of 10.06, outperforming those state-of-the-art methods. These results suggest that CAGLNet has the potential to significantly improve the effectiveness of defect detection in industrial production processes, leading to increased production yield and cost savings. Abbreviations: AT-RPN, adaptive tree-structure region proposal network; CAGLNet, cascaded adaptive global location network; CAT-RPN, cascade adaptive tree-structure region proposal network; CNN, convolutional neural network; DNN, deep neural network; EPNet, edge proposal network; FPN, feature pyramid network; FCOS, fully convolutional one-stage detector; FPS, frames per second; GMM, Gaussian mixture model; IoU, intersection-over-union; ROIAlign, region of interest align; RPN, region proposal network; ResNet, residual network; ResNet50_FPN, residual network and feature pyramid network; SABL, side aware boundary localisation; SSD, single-shot multiBox detector; TPE, Tree-structured Parzen estimator [ABSTRACT FROM AUTHOR]

We present here experimental verification of a theoretical model previously developed to estimate internal mechanical stress in steel-based elements by means of non-contact electromagnetic induction measurements. Results confirm the validity of the proposed model and demonstrate that stress below 50% of the elastic limit can be detected with standard electronics. [ABSTRACT FROM AUTHOR]

The article, titled "The Role of Migration in Classes of Labour: Work and Life in a Central Indian Steel Town," provides an ethnographic study of the industrial workers in the central Indian steel town of Bhilai. The author explores various topics such as labor recruitment, reservations, promotions, and unions, as well as the relationship between caste and class. The article highlights the significant role of labor migration in shaping and reproducing capitalism in Bhilai, emphasizing how migration created the city and transformed rural sending regions. It also discusses how migration contributes to the formation and consolidation of class divisions among workers, as well as the impact of migration on class-based superiority and non-class identities. The article concludes by raising questions about the potential for migration to challenge capitalism and foster working-class solidarity in the future. [Extracted from the article]

Variations in the microstructure and the dominant fretting wear mechanisms of carbon steel alloy in oscillatory sliding contact against stainless steel in a dry atmosphere were evaluated by various mechanical testing and microanalytical methods. These included scanning electron microscopy and energy dispersive spectrometry with corresponding elemental maps of the wear tracks, in conjunction with cross-sectional transmission electron microscopy of samples prepared by focused ion beam machining to assess subsurface and through-thickness changes in microstructure, all as a function of applied load and sliding time. Heavily dislocated layered microstructures were observed below the wear tracks to vary with both the load and sliding time. During the accumulation of fretting cycles, the subsurface microstructure evolved into stable dislocation cells with cell walls aligned parallel to the surface and the sliding direction. The thickness of the damaged subsurface region increased with the load, consistent with the depth distribution of the maximum shear stress. The primary surface oxide evolved as Fe2O3 and Fe3O4 with increasing sliding time, leading to the formation of a uniform oxide scale at the sliding surface. It is possible that the development of the dislocation cell structure in the subsurface also enhanced oxidation by pipe diffusion along dislocation cores. The results of this study reveal complex phase changes affecting the wear resistance of steels undergoing fretting wear, which involve a synergy between oxidative wear, crack initiation, and crack growth along dislocation cell walls due to the high strains accumulating under high loads and/or prolonged surface sliding.

Pre-strain is a key factor affecting the critical conditions for hydrogen-induced delayed cracking (HIDC). In this study, the threshold stress and critical hydrogen concentration for HIDC of MS1300 and MS1500 steels with different pre-strains were measured by constant load tensile (CLT) tests. The results demonstrated that although MS1500 has higher strength, its safe service strength is lower than that of MS1300 when the hydrogen content exceeds 0.5 wppm. Additionally, the hydrogen penetration, thermal desorption spectroscopy, and hydrogen microprinting methods were also used to analyze the hydrogen-induced failure mechanism. These studies provide an effective data reference for improving the industrial production process. [Display omitted] • The critical conditions for HIDC of MS1300 and MS1500 were established by CLT tests. • Hydrogen was enriched at the grain boundaries in MS1300 before and after deformation. • The HIDC sensitivity of martensitic steels increased with increasing pre-strain. • The safe service area of MS1300 is higher than MS1500 when the C 0 > 0.5 wppm. [ABSTRACT FROM AUTHOR]

This study investigated the interfacial phase evolution between magnesia refractory and low-density molten steel with different Al contents (0.5 % and 10 %) during the steel-slag reaction. Simulated experiments involving a refractory-steel-slag coupling reaction were conducted under laboratory conditions. The thickness and compositional distribution of the interface layers formed after the refractories were exposed to molten steel and slag were analyzed. The results indicate that, in the absence of slag, a MgAl 2 O 4 layer is formed at the interface between the refractory and molten steel due to the reaction between [Al] and Al 2 O 3 inclusions in the molten steel with the refractory. Upon the addition of slag, CaO in the slag is reduced to Ca and transferred into the molten steel, modifying the solid MgAl 2 O 4 layer at the interface into a primarily liquid CaO·MgO·Al 2 O 3 layer. The liquid interface intensified the erosion of the refractory by the molten steel, resulting in a thickened interface layer. The higher the Al content in the steel, the greater the degree of modification of the CaO·MgO·Al 2 O 3 layer by Ca. The Mg/Ca mass transfer process during the steel-slag reaction was simulated using the FactSage Macros calculation, and the differences in mass transfer between low and high Al contents were compared. The results indicate that under high Al conditions, the supply of Mg/Ca increases significantly. The simulation results were compared with numerous findings in the literature, confirming the accuracy of the simulation. [ABSTRACT FROM AUTHOR]

AbstractThe number of terrorist air blast attacks is increasing in a catastrophic way in the current era. However, the selection of material is a crucial task for designing a high-blast-mitigating protective structure. The experimental evaluation of the dynamic responses of various materials under a blast event is highly costly, with many restrictions and environmental pollution. Therefore, to avoid these difficulties, the current study demonstrated a series of dynamic explicit analyses to determine the dynamic responses of the plate structure of various materials and equal masses under air blast loads of 1–3 kg trinitrotoluene (TNT) at 300 mm stand-off distance (SoD). These loads were applied by using the Convention Weapons Effect Program (CONWEP). To correctly predict the mutilation behavior of metallic plates, the Johnson-Cook (J-C) material model was used, and to determine the damage behavior of composite plates, Hashin and Puck-Schurmann criteria were used. The Puck-Schurmann criterion was implemented via user defined VUMAT subroutine. These numerical approaches were first verified with the validations of the literature’s experimental results. To characterize the various plates’ blast mitigation capacity, their mid-point deflection, radial deflection at the instant of peak mid-point deflection, kinetic energy, internal energy, and damage patterns were compared. The influence of applied blast loads on the pressure and impulse variations on the plates has also been investigated. Findings of the analysis showed that the aluminum plate has the highest non-residual deflection resistance, and the composite plate had a maximum energy absorption characteristic under the air blasts. [ABSTRACT FROM AUTHOR]

Scratches and cracks in steel severely affect its service life and performance. However, owing to the irregular shapes and sizes of steel surface defects, defects within the same class may be different, whereas defects between classes may be similar. Existing methods focus only on spatial information, resulting in low detection accuracy. To alleviate these problems, this paper proposes the ECDY (EIFEM CARAFE DyHead) network to enhance the detection capability of steel defects. We first design a feature extraction module that focuses on the edge information of feature contours. This module uses the Sobel operator to extract the edge information of a feature and fuses it with the overall spatial information so that richer semantic information can be obtained. The module has improved accuracy in the YOLOv5, YOLOv8, and YOLOv10 versions, and uses fewer parameters and calculations. In particular, in YOLOv8x, mAP@0.5 increased by 2.5%, and the number of parameters was reduced by 12.4 M. Second, to retain the detailed information in the feature pyramid, and to better reconstruct features, we choose the content-aware reassembly feature method (CARAFE) as the upsampling method. Finally, the detection head was replaced with a dynamic unified detection head (DyHead) to adapt to different defect sizes and different task requirements. Compared with YOLOv8s, the proposed method improves precision by 1.6%, recall by 4%, and mAP@0.5 by 4%. This value is 4.2% higher than the mAP@0.5 of the current SOTA model RT-DETR-L in the field of object detection and has 23.2 M fewer parameters. [ABSTRACT FROM AUTHOR]

ABSTRACT The performance of repair coating solutions at damaged areas on prepainted galvanised steel was assessed in a cyclic corrosion test and after outdoor exposures in marine atmosphere. Different surface preparations at corroded defects before the application of the repair coatings were tested, for example, water‐jetting, the use of commercial cleaning solutions either acidic or alkaline, a chrome‐free conversion coating and the application of Zn‐Al primer coating. A poorer performance of the repair coatings was observed on damaged and corroded systems compared to damaged‐only panels. This was connected to the presence of remaining chlorides and corrosion products at scribes on corroded panels before repair coating application, which indicated the need for careful surface preparation to minimise the concentration of soluble salts. This was achieved by water‐jetting and the use of alkaline or acidic cleaning which provided satisfying corrosion performance of the repair coatings particularly with a two‐layer system as expected from the thicker layer of the reparation and presence of a primer. The weakest protection was observed when the one‐layer repair coating was applied on a chemically treated surface, which may be related to the weakness of the coating. [ABSTRACT FROM AUTHOR]

The purpose of this work was to determine the essence of the influence of the impact velocity (5, 7, and 9 m/s) on Hertzian stresses and the erosion mechanism of ferritic-pearlitic S355J2 steel. The investigations were carried out using a slurry pot tester. S355J2 steel showed a strong sensitivity to changes in impact velocity. A significant increase in erosion rate was observed at a velocity of 9 m/s. This increase was 5-fold and over 15-fold compared to velocities of 7 m/s and 5 m/s, respectively. The study of Hertzian stress is crucial in erosion research because it helps understand how impact energy is absorbed by the eroded material and the mechanisms that cause surface wear. A linear increase in mean contact pressure and maximum shear stress was observed with increasing impact velocity. The mean contact pressure increased from 4.3 GPa to 5.5 GPa and the maximum shear stress increased from 2.0 GPa to 2.5 GPa. The kinetic energy of the solid particles that hits the eroded steel is distributed in the contact area, which leads to various deformations and wear mechanisms. The primary type of deformation was fatigue degradation of the surface layers of the eroded steel. The high kinetic energy of solid particles contributed to the formation of plastic deformations and strongly deformed steel flakes. Higher impact velocities generally result in greater forces and contact stresses on the material surface. This led to the intensification of plastic deformation in the contact areas and increased the Hertzian stresses. [ABSTRACT FROM AUTHOR]

The paper presents experimental investigations and numerical analysis of bearing type lap joint behaviour with one bolt and two shear planes joining thin-walled steel parts. The aim of the study is to describe the actual force-displacement F-Δ relationship for the tested joints and to represent it numerically by validated models with varying degrees of geometry detailing in the finite element analysis. Validation involves determining properties of plates, bolts and the entire shear joint based on individual experimental testing. The obtained shear characteristic include all main stages of F-Δ connection behaviour, as elastic phase, friction, slip and bearing. Although bearing joints are analysed, friction-slip mechanism resulting from tightening of the bolts is also examined. Analyses also take into account existence of threaded portion of the bolt shank in bearing. FEA model with bolt thread confirmed its validity in terms of predicting load-bearing capacity with an overestimation of 1% with respect to the experimental average. However, simplified cylindrical model of the bolt shank appeared to be more reliable in terms of initial bearing stiffness, where the value was 20% higher comparing to the empirical results. An analytical characteristic of the considered joint was also derived based on the component method, which required certain assumptions and adjustments to include the actual phases of connection behaviour. This approach provided a satisfactory match to the experimental results, characterised by underestimations of maximum force and initial bearing stiffness of 2.5 and 7.6% respectively. [ABSTRACT FROM AUTHOR]

In the present article, the abnormal grain growth behavior of 20MnCr5 hot‐rolled bars with microalloying of 0.0198 wt% niobium low‐Nb steel (LNb) and 0.0241 wt% niobium high‐Nb steel (HNb) are investigated after heat treatment at 960 °C for 4 h. The radius of the hot‐rolled bars is 22.5 mm and the results show that the mixed grain region in LNb hot‐rolled bar is with a radius ranging from 9.5 to 22.5 mm, while the mixed grain region in HNb hot‐rolled bar is with a radius of 20 to 22.5 mm. The main precipitates are AlN and NbC, particles, and their composite precipitates. In LNb and HNb, the precipitates in outer region 1 are larger than those in inner region 3, and the number density is less. In the same region, the particle size of precipitates in LNb is larger than that in HNb, and the number density is much lower. Therefore, the mixed grains appear near the outer region of the experimental steels, and the mixed grain phenomenon of LNb is more serious than that of HNb. [ABSTRACT FROM AUTHOR]

For strengthening punching shear endangered areas, both (1) punching shear reinforcement such as stirrups, headed studs or lattice girders and (2) the use of steel fiber‐reinforced concrete (SFRC) have been investigated and applied for many years. In contrast, the combination of both of these strengthening methods is way less investigated and there are mainly studies on slabs with stirrups or headed studs in combination with SFRC which show a high potential for increasing the load‐bearing capacity for the same slab geometry. Relevant investigations with other types of punching shear reinforcement in combination with SFRC are not known. In order to fill this gap, four full‐scale tests were performed on slabs made of SFRC combined with a high‐performance punching shear reinforcement (Filigran FDB). These tests are based on a plain concrete benchmark test with FDB punching shear reinforcement from the literature. The present paper describes and discusses the design, execution, key results and lessons learnt from these experimental tests. The addition of steel fibers strengthens the punching shear reinforcement, leads to smaller crack widths, and increases the ductility of the compression zone around the column. This results in significantly higher punching shear resistance. While the tested punching shear reinforcement (FDB) increases the resistance of the plain concrete benchmark test to 2.16 times the resistance of plain concrete without shear reinforcement (VRk,c), the addition of steel fibers in the tests shows resistances up to 2.79 · VRk,c. Thus, the additional increase due to the fibers was up to 30%. [ABSTRACT FROM AUTHOR]

For decades, solid solution strengthening with up to 9 wt.% Ni has been the only successful strategy to obtain high strength and high impact toughness in bcc‐structured (ferritic or tempered martensitic) cryogenic steels. Until now coherent nano‐precipitates, an effective strengthening agent at room temperature, cannot be used to improve properties at cryogenic temperatures. Here, a new type of Mo‐rich nano‐B2 precipitates formed in a 6.5 wt.% Ni steel upon doping with 0.2 wt.% of Mo is reported. These precipitates are not only fully coherent with the matrix but are also shearable at 77 K. A high precipitate number density in excess of 2 × 1024 m−3 has been achieved by an industrially feasible process optimization, which brings both the cryogenic strength and impact toughness of the steel to the same levels as those of 9Ni steels. The Mo‐rich B2 precipitation strengthening, therefore, opens a new avenue for the design and development of low‐cost high‐performance cryogenic steels. [ABSTRACT FROM AUTHOR]

The influence of hydrogen on the fracture of X65 was studied. The fracture toughness in air was 369 MPa√m. The ASTM-valid fracture toughness with cathodic hydrogen charging was lower but was similar for these charging conditions 189 MPa√m and 181 MPa√m at 9 mA/cm2; 192 MPa√m and 179 MPa√m at 16 mA/cm2; and 177 MPa√m at 25 mA/cm2; even though the fractography changed from (i) ductile fracture by microvoid coalescence in air and at 9 mA/cm2 to (ii) more brittle fracture for hydrogen charging at 16 mA/cm2 and 25 mA/cm2, with flat facets and secondary cracks, which increased with increasing current density. • The influence of hydrogen on the fracture of X65 was studied. • The fracture toughness in air was 369 MPa√m. • The ASTM-valid fracture toughness with cathodic hydrogen charging was lower. • The fracture toughness with hydrogen was 152–186 MPa√m. • The fractography changed from ductile fracture to more brittle fracture with increasing hydrogen. [ABSTRACT FROM AUTHOR]

Influence of boron in a wide content range (0.0004–2.0%) and its joint effect with other alloying elements (Ti, Ce, Nb, Si, Mo, W, Al, N) on the structure and properties of austenitic stainless steels was analyzed. Due to segregation of boron along the grain boundaries and formation of various carbides, it is capable of increasing the strength and ductility, creep resistance and performance properties at high temperatures (> 600 °C). At the same time, a small boron content (≤ 0.004%), for example, in grade 304 stainless steel (Russian analogue—steel 08Kh18N10), leads to an improved corrosion resistance. However, with an increase in boron content (up to 2%), the positive effect disappears and steel becomes more susceptible to corrosion, while becoming stronger and inhibiting cracks formation during deformation due to grain refinement. [ABSTRACT FROM AUTHOR]

The Al alloy melting behavior and interfacial reactions during the steelmaking process of high-Al automotive steel were investigated in this study. The total dissolution time of Al bars (20 × 20 × 80 mm) in molten steel was quite short, decreasing from 21.4 s to 10.0 s with an increase in bath temperature from 1580 to 1620 °C. The Al alloy melting process at the molten steel temperature of 1600 °C included the formation of a solidified steel layer, the latter's rapid melting, and Al alloy normal melting, while at 1600 °C, the process included a second increase in the thickness of the solidified layer. Because steel elements such as [Fe], [C], [O], and [N] could diffuse during the whole Al alloy melting process, an Fe (Al)-FeAl-FeAl2-Fe2Al5-Al diffusion layer along the direction of the Al-rich matrix could be found at the Fe–Al interface. Moreover, FexO, Al2O3, and unstable AlN inclusions could be observed in the FeAl layer. This study also investigated how to reduce the number of these easily formed inclusions. Decreasing the pre-heating process time and dissolved oxygen content could be useful in decreasing FexO and Al2O3 inclusion formation. Some small-sized AlN inclusions formed in the center of the Al bars where they could not come into contact with the molten steel directly during the melting process; even for the immersion time of only 1 second, these inclusions were not stable in molten steel at the refining temperature and disappeared during the melting process. [ABSTRACT FROM AUTHOR]

To determine the thermal kinetic triplets and elucidate the reaction mechanism of thin intumescent fire-retardant coatings (IFR) of steel structures, one efficient combined kinetic approach was implemented in this study. Thermogravimetric experiments were conducted in air atmosphere at four heating rates, and the whole IFR thermal degradation process was divided into two stages. The average activation energy values derived by model-free methods were 78.9 kJ/mol and 175.16 kJ/mol for Stage I (0<α < 0.2) and Stage II (0.2<α < 0.9), respectively. Furthermore, the linear Coats-Redfern (CR) and non-linear Masterplots models were applied to identify the possible reaction mechanism. It was found that the F3/2 mechanistic model was better suited to the main thermal degradation process. Then model reconstruction based on the F3/2 mechanism model was performed. The results showed that the reconstructed model had a strict linear relationship in the independence analysis and KCE analysis, along with a good agreement between the theoretical and experimental results. The current study provided new insights into the systematic thermal degradation mechanism of IFR, and the proposed kinetic model would be helpful for the thermal protection prediction for steel structure during fire. [ABSTRACT FROM AUTHOR]

The effects of rare earth elements (REEs) on the corrosion behavior of weathering steels under a simulated immersion environment and a real atmospheric environment have been investigated in this paper. Although the corrosion rate of the indoor accelerated corrosion experiment (0.01 mol/L NaHSO3) is much higher than that of the real atmospheric exposure experiment, the addition of REEs can highly improve the corrosion resistance of test steels under both conditions. The improvement of the corrosion resistance can be attributed to the quick transformation of γ‐FeOOH into α‐FeOOH and the accelerated formation of a stable rust layer by REEs. Furthermore, the segregation of the REE inner rust layer increases the density of the rust layer and prevents corrosive particles from eroding the matrix. REEs can also promote the segregation of Cu, Cr, and other alloying elements in the rust layer, thus blocking the cracks and holes and enabling the formation of a continuous rust layer with good adhesion. [ABSTRACT FROM AUTHOR]

The paper presents chosen results of experimental tests performed on physical mock-ups of tensegrity triplex modules, approximately 1.2 m tall and of 0.5 m diameter, made of steel. A uniform and uniaxial static compressive loading is applied to three upper nodes of the modules at six different self-stress levels. Cable forces are measured using specially crafted force transducers of an electro-resistive strain-gauge type. Two types of struts with different slenderness are incorporated to analyze the influence of buckling on the behaviour of the modules. A simple three-parameter mathematical model is presented to explain the behaviour of the modules and discuss the obtained experimental data. The results show nonlinear behaviour in the equilibrium path, as well as, rapidly decreasing axial stiffness in the post-critical phase. An increase in prestress has a small influence on the stiffness in the chosen range of compressive loading. The experimental results are valuable for purposes of verification and validation of numerical studies and fill the lack of experimental data in the literature. [ABSTRACT FROM AUTHOR]

This study analyses the emergence of steel industry-related public sculpture in Britain in the late twentieth and early twenty-first centuries. The creation of these sculptures is viewed as part of the response of local authorities, artists and community groups to the large-scale loss of steel-making jobs and infrastructure in Britain since the mid-1970s. It posits that the rapid demolition of redundant steelworks plants after closure erased many of the physical reference points to steelmaking in its traditional heartlands, creating a material void which public sculpture has helped to fill. While belief in the ability of public art to stimulate urban regeneration lay behind the commissioning of many of these sculptures, especially from the 1990s onwards, we argue that they make more sense when viewed as a form of industrial heritage. Sometimes depicting the skills, clothing or iconic structures associated with steel, sculptures provided visual references to the industry, often in places where it no longer existed, thus becoming important sites of steel industry memory in Britain. [ABSTRACT FROM AUTHOR]

Low‐density steels have garnered widespread attention as novel lightweight materials. Owing to its high Mn and Al content, brittle AlN inclusions, detrimental to both steelmaking and steel properties, can precipitate directly from the molten steel. Employing slag absorption effectively removes these floating AlN inclusions from the molten steel. Herein, a series of analytical methods are utilized to investigate the dissolution behavior of AlN in CaO–Al2O3–MgO refining slag and CaO–Al2O3–F–Li2O–BaO mold flux. The results indicate that the initial dissolution temperatures of AlN in the slag and mold flux are 1361 and 1080 °C, respectively. The dissolution in the refining slag is attributed to the high‐temperature self‐decomposition of AlN, producing N2(g). In the mold flux, the dissolution reaction involves both the high‐temperature self‐decomposition of AlN and its reaction with Li2O in mold flux, generating N2(g) and Li(g). No reaction interface is observed at the AlN‐slag/mold flux boundary. As the dissolution mass of AlN in the slag/mold flux increases, the Al2O3 content in the slag/mold flux rises. The main phases in slag transition from Ca9(Al6O18) to Ca12Al14O33 and Ca3Al2O6. In the mold flux, the LiBaF3 phase disappears, and the 11CaO·7Al2O3·CaF2 phase, which can degrade the flux's physicochemical properties, becomes the dominant phase. [ABSTRACT FROM AUTHOR]

A 3D discrete phase model (DPM)‐ and volume of fluid–coupled model is developed to investigate the multiphase flow in a 260 ton argon‐stirred ladle. The flow field and interfacial behavior in the argon‐stirred ladle are accurately predicted. Then, the Lagrangian DPM is used to trace the motion of inclusions in the liquid steel. Residence time maps, which provided the residence time required for inclusions travelling from the bulk liquid steel to the steel–slag interface, are proposed and plotted as functions of inclusion diameter and percentage of inclusions. For inclusions smaller than 10 μm, the average residence time is size‐independent but decreases from 175 to 93 s with an increment in the gas flow rate from 50 to 400 NL min−1. With increasing the inclusion size, the average residence time is dependent on both gas flow rate and inclusion diameter. When the inclusion diameter increases to 1000 μm, the average residence time is almost independent of the gas flow rate. The current model overestimates the inclusion removal rate. However, this overestimation indicates that only appropriately considering the behavior of inclusions at the steel–slag interface can accurately predict the removal of inclusions in argon‐stirred ladles. [ABSTRACT FROM AUTHOR]

High‐aluminum advanced high‐strength steels have received increasing interest due to their excellent combination of strength and ductility. The control of nonmetallic inclusions in steel is among the most important issue for the production of high‐aluminum steel. This study proposes a model for the evolution of size distributions of AlN inclusions during solidification of steel based on the Kampmann–Wagner numerical model and microsegregation calculation. Both homogeneous (pure AlN) and heterogeneous precipitations (AlN+oxide or MnS) are described using homogeneous nucleation and free growth models of Greer et al. respectively. The model is applied to calculate the size distributions of AlN in high‐Al (up to 5%) Fe–Cr–Al steels and high‐ and medium‐manganese steels and validated by the experimental data in the literature. The model correctly describes the influence of cooling rates on the precipitation of AlN in Fe–Cr–Al steels and high‐manganese steels, and the sizes of AlN are reduced and the number densities of AlN inclusions are increased by increasing the cooling rate. The effects of nitrogen and aluminum concentration in medium‐manganese steel on inclusion precipitation are investigated by the model calculation. The increases in nitrogen and aluminum concentration facilitate the homogeneous precipitation of AlN inclusions. [ABSTRACT FROM AUTHOR]

Purpose: The research paper comprehensively investigates the gear tooth deflection of standard thermoplastic gears with steel gear as the driver and driven companions. An accurate mapping of characteristic contact regions between the meshing gears was done, and the behaviour of the gear tooth in the premature and prolonged contact zones was studied. Design/methodology/approach: The study employs the finite element method to conduct a quasi-static 2D analysis of meshing gear teeth. The finite element model was created in AutoCAD and analysed using the ANSYS 19.1 simulation package. Findings: In the polymer-polymer gear combinations, premature and prolonged contact primarily occurs along the addendum radii of meshing gears, whereas a novel contact phenomenon was observed in the coast side for polymer-metal and metal-polymer combinations, exhibiting a path perpendicular to the standard drive side contact. As well, the deflection of the tooth alters the load distribution across the interlocking gears, leading to a decrement in the root stresses. Originality/value: The Lewis bending equation demonstrates that bending stresses depend solely on the applied load and the geometry of the tooth. It does not consider the effects of deflection. However, the computational results showed that the gear tooth deflection caused by different gear pair combinations also affects the bending stresses. The contact stresses observed in the polymer-polymer gear combination were observed to be within the material's proportional limit. However, when a steel gear is paired with a polymer gear, the contact stresses exceed the proportional limit due to coast side contact. [ABSTRACT FROM AUTHOR]

A shake table test using a full-scale 2-story steel moment frame was conducted to investigate the peak floor acceleration (PFA) and the peak component acceleration (PCA), which directly affect the seismic demand on nonstructural elements. The main focus of this study was to evaluate the effects of structural and component nonlinearity on the nonstructural seismic demand. The PFA reduction suggested by ASCE 7-22 to account for structural nonlinearity was shown to be larger than the experimental results for low-to-moderate ductility levels. The analysis on the resonant PCA showed the importance of structural nonlinearity on the elastic CAR (=PCA/PFA). The high resonant PCA around the fundamental period of the elastic test frame (7 times PFA) was effectively decreased as the test frame experienced a moderate level of ductility; PCA was lowered by 36% and 25% on the 2nd and roof floors, respectively. The effect of component yielding on the PCA was evaluated based on the test results of steel racks mounted on flexible and rigid access floors. The PCA reduction depending on the component ductility level was less than the relevant provisions of ASCE 7-22, and the reason was discussed from the perspective of the pinched hysteretic behavior of the tested specimens. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) causes significant heat accumulation within the deposited layers making it difficult to achieve necessary geometrical accuracy and built properties. A cost-effective technique to mitigate build-up heat and improve the thermal cycle is accomplished with the introduction of an inter-layer dwell time (ILDT). The study investigates the impact of ILDTs of 60, 90, 120, 150, and 180 s on the properties of the printed parts. The grain refinements were achieved at higher ILDT with no appreciable changes in the compositions. However, a slight increase in oxides and δ -ferrite was detected. The study found improved part density, mechanical and tribological performance while reduced corrosion-resistant properties with increased ILDT. Furthermore, to understand the effect of ILDTs on location-based thermal cycling and distribution, numerical models of the process were established. The peak temperature gradually reduces with an increase in ILDT. Heat accumulations within the three-layered WAAM-built structure lessen by 70% approximately with increases in ILDT from the 60 s to 180 s. The results observed repeated thermal cycles of the previously deposited layers and reduction of peak temperatures with subsequent layer deposition irrespective of the ILDTs. The trough temperature slightly reduced with ILDT; however, at higher delay periods the variations were found to be more stable. The study discovered too low and too high ILDT is detrimental and therefore an appropriate mid-range ILDT of 120 s is suggested to fabricate medium-size WAAM-built components based on experimental and numerical investigation considering overall production time and functional properties. [ABSTRACT FROM AUTHOR]

High-strength steels (HSSs) have been gaining increasing attention in recent years because of their potential application for lightweight structures. Hybrid structural steel I-sections, featured by dissimilar strength grades for constitutive plates, provide a more economical solution to suit bending loading scenario. This study conducted experiments on nine I-sections with Q690 flange plates under four-point loads, incorporating three different web strength grades including Q690, Q460, and Q355. Furthermore, the local buckling behavior of representative I-sections with various section geometries was analyzed using a validated numerical method to understand the role of web strength grade. Test and numerical analysis results revealed that the section with web steel in the strain hardening stage exhibited different levels of ductility among specimens with different strength webs. It was also observed that earlier yielding or inelastic buckling of the lower strength web plate in hybrid I-sections affects the local buckling behavior of I-girders, in terms of moment resistance and rotation capacity. In addition, the initial local imperfection mode used in numerical analysis was found to affect the rotation capacity of I-girders, but the effect of web strength grade remains consistent among I-sections with the same local buckling deformation mode. This study provides further insights into the local buckling behavior of hybrid I-sections subjected to uniform bending, laying the foundation for further development of design methods. [ABSTRACT FROM AUTHOR]

This paper introduces a retrofit design procedure for reinforced concrete (RC) frame buildings using alternative steel bracing systems based on the simple lateral mechanism analysis (SLaMA). Employing a displacement-based design approach, the procedure captures the actual behavior of existing buildings and the contribution of the bracing system. The retrofit design process and seismic assessment procedures are outlined, followed by the proposed SLaMA-based retrofit design procedure. The design procedure is demonstrated on pre-1970 four-story and eight-story RC case study frames, targeting maximum displacements informed by the expected failure mechanisms identified using a detailed seismic assessment (DSA). The New Zealand Society of Earthquake Engineering 2016/017 Seismic Assessment Guidelines' SLaMA method is utilized for DSA, revealing that the frames are potentially earthquake-prone with specific failure mechanisms and seismic capacities. After retrofitting with a concentric braced frame (CBF), buckling-restrained brace (BRB), and CBF with friction dampers, the failure mechanisms are modified, resulting in seismic capacities exceeding 100% New Building Standard (NBS). Evaluation of local and global behavior post-retrofit enables the determination of the advantages and disadvantages of alternative brace systems. Nonlinear time-history (NLTH) analyses using a lumped plasticity model verify the results, affirming the viability and practicality of the SLaMA-based retrofit design procedure for selecting and designing appropriate interventions in concrete frame buildings. [ABSTRACT FROM AUTHOR]

Four-point bending tests have been widely applied for investigating flexural behavior of different materials. However, there are no guidelines or standards relating to four-point bending tests for pipes. A steel pipe with a diameter of 154 mm and 3.4-mm wall thickness was instrumented with distributed fiber-optic strain sensors and tested in four-point bending. The measured strains at the crown, springlines, and invert deviated from results calculated using beam theory. This strain deviation is investigated using numerical analyses, and it is found that local deformations along the length of the pipe due to concentrated loads at load and support locations contributed to the deviation. Parametric studies are conducted using different geometries of wood support blocks, specimen lengths, and pipe thicknesses to investigate their impact on the strain distribution with the pipe. Recommendations for reducing the strain deviation at the midspan of the specimen are given for four-point bending tests carried out on the steel pipes. [ABSTRACT FROM AUTHOR]

Quasi-static compression/tension, dynamic compression/shear mechanical property tests, fracture morphology characterization, dynamic response experiment, numerical simulation, and calculation of the ultimate penetration velocity of the high-strength steel under the impact of large mass low-velocity fragments and small mass high-velocity fragments were carried out to study the ballistic performance of high-strength steel used for armor vehicle protection and clarify its dynamic response under Ballistic impact. The fracture mode of the high-strength steel under dynamic impact compression and shear was shear failure. A large number of fine parabolic shear dimples were formed on the fracture surface. The high-strength steel had an obvious strain rate strengthening effect and adiabatic shear sensitivity. The plug formed under the low-velocity impact of a large mass fragment was a cone shape, and the impact area of the target plate underwent slight bending plastic deformation. The damage of the fragment to the target plate includes both adiabatic shear failure and ordinary shear failure. Under the high-velocity impact of small mass fragments, the fragments were seriously deformed and destroyed, and the damage model of the target plate is adiabatic shear failure. [ABSTRACT FROM AUTHOR]

The Shennong Lake Bridge stands as a prominent landmark in Changzhi City, located in Shanxi Province. Constituting the primary span is a "herringbone" configuration, employing a single tower double cable plane cable-stayed design with spans of 2 × 130 m and a deck width of 47 m. The complex bridge tower structure poses a challenge to the design of the bridge. This study elucidates the procedural intricacies of employing a three-dimensional parametric approach in shaping the cable tower. By leveraging the merits of history-based parametric modeling and skeleton-template design, a comprehensive landscape blueprint has been developed, with a primary focus on the architectural layout of the cable tower. The collision rectification issue between the bridge tower and the cable has been resolved using a 3D parametric model. Following the culmination of construction efforts, the final structure harmoniously aligns with the initially envisioned landscape depictions. Through meticulous optimization of design protocols for intricate landscape-integrated bridges, this endeavor extends its potential utility as a salient reference for akin undertakings. [ABSTRACT FROM AUTHOR]

The present study concentrates on experimental characterization and finite element (FE) simulation of a novel friction stir spot welding (FSSW) of AA6063-T6 and CRCA/IS-513 alloys using a consumable sheet (FSSW-C) at varying tool plunge depth (TPD). In this method, the rotating tool does not plunge into the base sheets (AA6063-T6 and CRCA/IS-513) that are located at a specific distance between the edges. Rather, it plunges through the consumable sheet kept at the top of the base sheets. As the tool moves down during plunging, it plasticizes the consumable sheet material. The plasticized material helps in developing permanent joint between the base sheets. Due to this arrangement exorbitant tool wear is entirely avoided. Experimental characterization explores joint formation, interface traits, microhardness, temperature evolution, and bendability at different tool plunge depths (TPDs). DEFORM-3D FE simulations understand material flow, strain, and strain rate evolution during FSSW-C across varying TPDs. The joint macrograph reveals the complete merging of the consumable sheet with AA6063-T6 base metal, while it is predominantly mechanical bonding between the consumable sheet and steel base metal. Keeping other FSSW parameters constant, TPD of 1.8 mm is found to be the optimum level with a peak shear load of 0.5 to 0.8 kN during bend tests. At 2.2 mm TPD, 1.7-μm-thick IMC layer comprises of AlFe and FeAl3 exhibits hardness of 300 HV. Shear friction factor of 0.4 is the optimized value for accurate prediction of temperature during FSSW-C. 4-10% deviation is observed between the predicted and experimentally measured peak temperature. Strain rates between 3 and 127 s−1 are predicted at different locations during FSSW-C, closer to the range available in FSP literature. Material flow analysis reveals seamless merging of AA6063-T6 base sheet and consumable, forming a residual thin consumable layer atop the steel base sheet. [ABSTRACT FROM AUTHOR]

In order to study the axial compression performance of steel pipe concrete short columns filled with steel slag micronized ultra-high-performance concrete (UHPC), this paper designs 27 steel pipe UHPC short columns for axial compression test and compares and analyzes the axial compression performance of the specimens in terms of the damage mode, the deformation curve, and the coefficient of strength enhancement, which is aimed at investigating the differences in the actual load-bearing performance of steel pipe UHPC short columns through changes in the aspect ratio, concrete type, and steel content rate, and so on. The purpose of this paper is to compare and analyze the axial compressive performance of the specimens in terms of damage mode and strength enhancement factor in order to investigate the difference in the actual bearing capacity performance of steel pipe UHPC short columns through the changes in length-to-diameter ratio, concrete type, and steel content. The test results show that the axial compressive performance of steel slag powder steel pipe UHPC short columns is greatly affected by the L/D ratio and steel content; the specimen bearing capacity increases with the increase in the wall thickness of the steel pipe and decreases slightly with the increase in the L/D ratio, and the steel fibers can effectively improve the deformation of the concrete so as to enhance the composite effect with the steel pipe; the contribution of the core UHPC to improve the value of bearing capacity accounts for a higher percentage when UHPC with 1% steel fiber dosage and 20% coarse aggregate dosage gave the best uplift with no change in the type of steel pipe. In this paper, the axial compression test bearing capacity results of steel slag micro powder steel pipe UHPC short column are compared with the calculated bearing capacity results of domestic and international specifications and analyzed from the perspectives of perimeter compression strength, steel fiber mixing of core concrete, and the relevant parameter design suggestions for high-strength steel pipe concrete specimens are put forward. [ABSTRACT FROM AUTHOR]

To address the issues of low accuracy and efficiency in traditional image processing algorithms for steel surface defect detection, a novel steel surface defect detection algorithm based on YOLOv8-TLC is proposed. To more accurately detect defect targets in images that are missed due to their large size, an additional scale detection layer is introduced. Meanwhile, the Large Selective Kernel (LSK) attention mechanism is incorporated to deeply explore spatial structural information that is highly relevant to the steel surface defect targets, further enhancing the model's spatial feature extraction capabilities. A triple spatial pyramid module is also constructed to address the problem of redundant feature extraction. Additionally, the C2f-DS module is designed to ensure the acquisition of richer gradient flow information without increasing the number of parameters. Experimental results on the NEU-DET dataset show that the YOLOv8-TLC algorithm achieves a mean average precision (mAP) of 79.8%, improving the mAP by 3.2% while enhancing detection speed. [ABSTRACT FROM AUTHOR]

The simplified method of the equivalent compression flange represents an illustrative and easy‐to‐use engineering model for lateral torsional buckling. The basic concept of the verification procedure has existed since its introduction in the 1950s. It is still frequently used today for preliminary design and application cases where the solution of the 'correct lateral torsional buckling problem' is complex and time‐consuming. To adapt the method to the current state of the art, it was further developed in the framework of the Eurocode 3 evolution. This 'new' method is part of the second generation of Eurocode 3, Part 1‐1 and is valid for classes 1 to 3 cross sections in major axis bending. The method must be adapted for use in other contexts and for specific applications. Applying the equivalent compression flange verification method to the structural fire design of building structures must consider the temperature‐dependent material properties of steel and their impact on the stability behaviour. Moreover, typical applications for bridge structures, runway beams, and H‐piles in combined walls require additional consideration of class 4 cross sections and various combined loadings, e. g., N–M interaction behaviour. This article presents theoretical studies on extending the simplified method of the equivalent compression flange to meet these demands. Finally, the application of the verification method is demonstrated in working examples. [ABSTRACT FROM AUTHOR]

The flanging process is widely used in stamping production: when collar drawing small holes for threads or to increase the stiffness of a draw piece. It can also replace the operation of deep drawing cylindrical draw pieces with a large flange followed by cutting the bottom. The paper discusses the influence of the shape of the punch and the grade of material on load changes at various collar drawing coefficients. Flat, spherical and conical punches and samples made of EN-AW 1050A aluminium, Cu-ETP copper, CuZn37 brass, S235JRG2 steel, X6Cr17 steel and X5CrNi18-10 steel were used for testing. The relative thickness of test pieces was 0.015 (which corresponded to a thickness of 1 mm and a blank diameter of 66 mm). Various collar drawing factors ranging from 0.32 to 0.54 were adopted in the studies. An analysis of the obtained height of collars and wall thicknesses was carried out. The experimental tests were carried out using special tooling mounted on a testing machine with a 20 kN load for 0.5 metrological class. Changes in the force as a function of the displacement of the punches were recorded using Test&Motion software that is commonly applied in research laboratories. Based on the obtained results at various technological parameters, possibility of flanging process was evaluated in industrial conditions. [ABSTRACT FROM AUTHOR]

Nature has long inspired technological innovations, fostering the rapidly developing field of bionics. Inspired by the microstructure of bamboo, we have developed a bamboo-like structure for steel. This novel steel achieves a tensile strength exceeding 1200 MPa and a uniform elongation nearing 68%, resulting in a product of strength and uniform elongation up to 83 GPa·%. The high strength of the steel is primarily attributed to its ultra-fine lamellar grains. Additionally, the graded occurrence of multiple deformation mechanisms collectively maintains its exceptional work-hardening capability. This study presents a new approach to enhancing the performance of medium-Mn steels. Impact Statement: A bamboo-like steel consisting of lamellar ferrite and austenite alternating along the rolling direction, providing a new path to produce medium-Mn steels with outstanding mechanical properties. [ABSTRACT FROM AUTHOR]

We examined the hydrogen diffusion behavior in the Al–Si-coating layer which underwent the press-hardening simulation. The microstructure evolution, in particular, the type of intermetallic compounds, was revealed to have a remarkable influence on the hydrogen absorption. It was found that the formation of AlFe in the coating layer was advantageous regarding to the suppression of hydrogen penetration across the coating layer, which was originating from the lower hydrogen diffusivity compared to the Al5Fe2. [ABSTRACT FROM AUTHOR]