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The increasing demand for lightweight vehicles, while ensuring collision safety, has led to the growing utilization of high-strength steel sheets. Accordingly, the hot stamping process, which involves heating the material and shaping it in a die while simultaneously cooling it, has gained significant attention. However, the inclusion of heating and cooling processes in the hot stamping engineering presents competitive disadvantages in terms of cost. As a result, numerous studies are being carried out to overcome these challenges and improve productivity. In particular, the sidewall areas of the vehicle body parts, which thin out during the stamping process, can experience a reduced cooling rate compared to other areas. To counteract the potential risk of a relative decrease in strength in these areas, extending the pressurization time of the press becomes necessary. In this study, by introducing groove patterns on the surface of the die used in the hot stamping forming and cooling processes, it was investigated how to enhance the cooling rate of the sidewall of the vehicle part without necessitating additional press dwell time. Using this approach, it was possible to achieve a strength of over 1.6 GPa and a dimensional accuracy of -0.06 mm within a short in-die quenching time of 6 s. [ABSTRACT FROM AUTHOR]

Considering the advantages of hybrid steel I-section beams in reducing engineering costs and fully utilizing the mechanical properties of steel, and the lack of research on their ductility, hybrid steel I-section beams were tested to analyze the effects of the plate width–thickness ratio and steel strength matching on the flexural bearing capacity and ductility. The steel strength matching of the hybrid steel I-section beam with a high steel strength utilization rate and good ductility was related closely to the section size. Additionally, a parametric analysis based on the finite- element method was performed for further study. The steel strength ratio φ of the web to the flange with the best ductility was less than 1, and φ decreased with an increase in flange steel strength. The steel strength utilization rate and ductility decreased with an increase in φ. Based on the parametric analysis results, the optimal range of φ in hybrid-steel I-section beams with flange steel strength of 460–690 MPa was 0.56–1. The plate width–thickness ratio limit of the ductile section decreased with the decrease of φ. Considering the plate interaction and steel strength matching, a sectional ductility design method is proposed that is more applicable to hybrid steel I-section beams than existing methods. [ABSTRACT FROM AUTHOR]

The illustrations above demonstrate that as the percentage of niobium increases, the grain size decreases, leading to an increase in the stability of transformation induced plasticity steel. This, in turn, results in improved mechanical strength. The optimal volume fraction of retained austenite for a significant transformation induced plasticity effect to occur is reported to be in the range of 10 vol. %–20 vol. %. The volume fraction of retained austenite directly determines the carbon content and grain size of the retained austenite, its two main stabilization factors. The stability of the retained austenite dictates when the strain‐induced martensite transformation (SIMT) occurs during straining of transformation induced plasticity high strength steel. Unstable retained austenite transforms almost immediately upon deformation, increasing work hardening rate and formability during the stamping process. At the appropriate stability of the retained austenite, the Strain‐Induced Martensite Transformation begins only at strain levels beyond those produced during stamping and forming, and the retained austenite is still present in the final part; it can transform into martensite in the event of a crash, providing greater crash energy absorption. The tensile strength level of micro‐alloyed transformation induced plasticity steels may exceed 1 GPa. Grain refinement mechanism is considered as the most applied mechanism used in increasing of steel strength without deterioration of ductility and toughness. Recently, it was proposed that the grain refinement could act positively on promoting the transformation induced plasticity effect of advanced high strength steel through improving the stability of retained austenite. In this research, quenching and partitioning heat treatment technique was applied to four grades of low carbon steel with different percentage of niobium. Then, the effect of niobium on grain refinement has been detected by microstructure observations. Mechanical properties and strain hardening properties of investigated steel have been determined. In addition, by using x‐ray diffraction, as well as a new electric resistance‐based sensor, it was possible to characterize the stability of the retained austenite through the plastic deformation of steel. Grain refinement by using of niobium has a great impact on promoting the stability of retained austenite against the plastic stress at the plastic deformation zone. [ABSTRACT FROM AUTHOR]

A systematic study is performed on the development of hot-dip galvanized coatings on a Mn-containing high-strength steel sheet by varying the dew point (− 50, − 10, and + 10 °C) during inter-critical annealing of the steel strip at 800 °C. It also studies the effect of dew point on the corrosion behavior of the coatings in freely aerated 3.5 wt% NaCl solution. The reducing gas atmosphere consists of 95% N2 and 5% H2, where inter-critical annealing is carried out. Surface oxidation of the steel has a strong effect on the development of sound coating. A defect-free adherent galvanized coating is obtained on the annealed steel surface at a fixed dew point of + 10 °C, and it is attributed to the fine and continuous compact Fe-Al crystals compared to galvanized coatings produced at other dew points as well as the highest atomically dense (0002) basal plane. This also leads to the lowest corrosion rate (~ 0.164 mm y−1, where mm and y stand for millimeter and year, respectively) of the galvanized coating produced at a dew point of + 10 °C when compared with galvanized coatings produced at dew points of − 50 °C (~ 0.279 mm y−1) and − 10 °C (~ 0.259 mm y−1). The lowest corrosion rate of the galvanized specimen developed at + 10 °C dew point can be attributed to the uniform and defect-free coating surface, together with the dominance of the more atomically dense (0002) basal plane. [ABSTRACT FROM AUTHOR]

The main goal of this study is to examine the buckling properties of a composite material that combines graphene-origami-enabled features with magnetostrictive facesheets. The nonlocal theory, as developed by Eringen, has been used for the purpose of quantifying the small-scale parameter. However, the system being presented is based on the theoretical framework established by Winkler and Pasternak, which incorporates the analysis of a deformable medium. The use of a theoretical framework referred to as higher-order sinusoidal shear deformation theory has been utilized to formulate the governing equation. The governing equation is then solved via the Galerkin solution approach, while considering various boundary conditions. In order to assess the precision and effectiveness of the present inquiry, the findings are juxtaposed with the prevailing scholarly publications in the academic literature. Furthermore, this study aims to examine the impact of several factors, including as the weight fraction, hydrogen atom coverage, aspect ratio, and temperature, on the critical buckling load. The findings of the present investigation indicate that an increase in the weight fraction of graphene-origami-enabled material leads to an increase in the buckling load. The main aim of this study is to improve the understanding and predictive capability of engineers and designers about the phenomenon of buckling response. The aforementioned data have the potential to provide advantages in the advancement of nanoscale systems, including highly sought-after technologies such as sensors and actuators. [ABSTRACT FROM AUTHOR]

With the continuous integration of semiconductor devices, the requirements of the size accuracy and surface quality of etched lead frames are stricter. The etchant is a key factor in the etching process and etched surface quality, while the effects of the difference in etchants on the etched surface morphology of Cu alloy have not been directly studied. In this study, aqua regia, acidic FeCl3 and two CuCl2 solutions were used as etchants, and different CuCrSn specimens were etched and characterized. The results show that the etching rate in aqua regia is high, and the grain orientation, grain boundary (GB) and dislocations have significant influences on the local etching rate. The preferential etching of some atomic planes forms steps between the grains with different orientations, and preferential etching around the GB and dislocation group forms grooves, resulting in high surface roughness. For the surfaces etched by the FeCl3 and CuCl2 etchants, the steps and grooves are blurred; thus, they are less rough. The CuCrSn alloy surface etched by the aqua regia is clean, with little Cr-rich particles, while high-density Cr-rich particles remain on the surfaces etched by the FeCl3 and CuCl2 etchants. For the same kind of etchant, the ion concentration can affect the etching mechanism, rate and the etched surface morphology. [ABSTRACT FROM AUTHOR]

Considering the high-speed and high power density technical specifications of new energy vehicle motors, there is a growing demand for rotor strength as motor peak speeds reach 20,000 r/min and beyond. The utilization of non-oriented silicon steel with a high yield strength in rotors has emerged as a promising approach to increase motor speed. However, the magnetic and mechanical properties of high-strength silicon steel under variable temperature conditions have not been fully explored, particularly in regards to their impact on motor torque, efficiency, and speed. This manuscript investigates the behavior of high-strength silicon steel before and after annealing and at different temperatures, analyzing its influence on high-speed motor performance. The validity and feasibility of this study are confirmed through prototype testing, providing a comprehensive reference for engineering design. [ABSTRACT FROM AUTHOR]

Medium-carbon, high-strength steels are widely used in the field of hydrogen energy because of their good mechanical properties, and they can be readily tailored by heat treatment processes such as the normalizing–tempering (N&T) and quenching–tempering (Q&T) methods. The hydrogen embrittlement (HE) susceptibility of a medium-carbon, high-strength steel was investigated utilizing microstructural characterization with scanning electron microscopy (SEM), the electron backscatter diffraction (EBSD) technique, and transmission electron microscopy (TEM). A study was also conducted on the steel's hydrogen transport behavior as affected by the N&T and Q&T treatments. The steel contained more hydrogen traps, such as dislocations, grain boundaries, lath boundaries, and carbide interfaces, after the Q&T process, which was associated with a lower HE sensitivity when comparing the two treatments. In comparison, the N&T process produced larger-size and lesser-density carbides distributed along the grain boundaries, and this resulted in a relatively higher HE susceptibility, as revealed by the slow-strain-rate tensile (SSRT) tests of the hydrogen-charged steels and by the fractographic study of the fracture surface. [ABSTRACT FROM AUTHOR]

In this article, the effect of Ce element on the microstructure and mechanical properties was studied by Ce addition to the hot‐formed steel. Scanning electron microscope and energy dispersive spectrometer (SEM‐EDS) was used to analyze the improvement effect of Ce on inclusions and the effect of inclusions on fracture behavior; Electron back scattering diffractometer (EBSD) was used to analyze the refinement and strengthening effect of Ce on martensitic grains; transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) was used to analyze the microstructure strengthening effect and microalloying effect of solid solution Ce in hot‐formed steel. Through a systematic analysis of mechanical properties and microstructure, the mechanism of Ce enhances the strength and elongation of hot‐formed steel was clarified. Besides, this work provides a research basis for further improving the safety and machinability of hot‐formed steel. [ABSTRACT FROM AUTHOR]

In the companion paper, test results were presented to explore the flexural performance of cold-formed ferritic stainless steel (FSS) closed built-up beams. Each specimen was fabricated by joining two lipped channels in a face-to-face configuration and securing them with spot welds at intermediate points along the beam span. Sectional aspect ratio, compression flange's sectional slenderness and moment gradient were the key parameters varied to explore their influence on the flexural response of such members through tests. The current paper establishes a simplified finite element (FE) model of cold-formed FSS closed built-up beams and verifies it against the test results. Further, an extensive parametric study is carried out using the validated FE model to generate a large pool of data points. A wider database comprising of test results, numerical results obtained from this study and numerical results available in the companion paper were used to critically examine the adequacy of the current Australian Specifications (AS/NZ), American Standard (SEI/ASCE-8), European Code (EN 1993-1-4), Modified Eurocode approach suggested by Gardner and Theofanous, and Direct Strength Method (DSM) in North American Specification (AISI-S100: 2016), Modified DSM approach proposed by the authors in the literature and Continuous Strength Method (CSM) for cold-formed steel (CFS) flexural members. This makes the current study the first to extensively assess the accuracy of the various design guidelines available in the codes and other relevant literature, which explicitly highlighted their grave limitations. Accordingly, through suitable modifications and recommendations, new design rules are proposed to reliably and safely predict the flexural capacity of cold-formed FSS closed built-up beams. [ABSTRACT FROM AUTHOR]

One of the efficient and cost-effective structural elements is the castellated steel beam (CSB) which can significantly lower building costs. This fact encourages studying the structural behavior of such beams and determining the castellation ability to maximize flexural stiffness while avoiding shear failure. For this purpose, experimental and theoretical investigations were carried out. The experimental work consisted of fabricating and testing six beams with span lengths of 2000 and 1038 mm and expansion ratios of 1.0, 1.25, and 1.50. Meanwhile, the theoretical part included an adopted analytical procedure that produced an unprecedented theory-based formula giving the maximum expansion ratio ( ψ m ), thus determining the nominal flexural strength of any castellated section. On the other hand, the experimental results, which covered a variety of mechanisms and failure modes, including overall flexural failure, shear and compression buckling of the web posts, tearing and inelastic local buckling, and compression buckling of the top tee, confirmed that ψ m should not be exceeded to fully utilize the flexural capacity of CSBs. The formula for ψ m was then graphed for design purposes, and it was found that it relies on three major parameters: loading type factor (Cc), span length (L), and properties of the root section, upon which any castellated section has a distinct ultimate flexural strength. Furthermore, the ultimate flexural strength increases as the loading type factor decreases and the span length increases. [ABSTRACT FROM AUTHOR]

Over the past several decades, conventional spectral analysis techniques of polluted white dwarfs have become powerful tools to learn about the geology and chemistry of extrasolar bodies. Despite their proven capabilities and extensive legacy of scientific discoveries, these techniques are, however, still limited by their manual, time-intensive, and iterative nature. As a result, they are susceptible to human errors and are difficult to scale up to population-wide studies of metal pollution. This paper seeks to address this problem by presenting cecilia , the first machine learning (ML)-powered spectral modelling code designed to measure the metal abundances of intermediate-temperature (10 000 ≤ T eff ≤ 20 000 K), Helium-rich polluted white dwarfs. Trained with more than 22 000 randomly drawn atmosphere models and stellar parameters, our pipeline aims to overcome the limitations of classical methods by replacing the generation of synthetic spectra from computationally expensive codes and uniformly spaced model grids, with a fast, automated, and efficient neural-network-based interpolator. More specifically, cecilia combines state-of-the-art atmosphere models, powerful artificial intelligence tools, and robust statistical techniques to rapidly generate synthetic spectra of polluted white dwarfs in high-dimensional space, and enable accurate (≲0.1 dex) and simultaneous measurements of 14 stellar parameters – including 11 elemental abundances – from real spectroscopic observations. As massively multiplexed astronomical surveys begin scientific operations, cecilia 's performance has the potential to unlock large-scale studies of extrasolar geochemistry and propel the field of white dwarf science into the era of Big Data. In doing so, we aspire to uncover new statistical insights that were previously impractical with traditional white dwarf characterization techniques. [ABSTRACT FROM AUTHOR]

• Collaborative Optimization of Simplified Sections of steel/aluminum vehicle body. • Simplified Section was translated into Complex Section under Constraints of Sectional Mechanical Properties. • Optimization method for complex sections controlled by proportional vectors was established. A multi-level matching transformation and optimization design method for complex sections of thin-walled structures in steel/aluminum vehicle body skeleton was proposed. The problems of lengthy body performance numerical analysis and low optimization efficiency were solved by the rapid collaborative optimization of simplified cross-sections and performance of the body skeleton. A complex cross-sections shape library of thin-walled structures in steel/aluminum body skeleton and formulas for solving section mechanical properties were established, which overcame the difficulty of translating simplified cross-sections of thin-walled structures in steel/aluminum body skeleton to actual complex sections. A precise optimization method for complex cross-sections of thin-walled structure controlled by proportional vectors was established, which solved the defect that it was difficult to precisely control the arbitrary change of complex cross-section shape, and provided a new way for lightweight optimization design of complex cross-sections. The proposed method achieved the rapid collaborative design of steel/aluminum body thin-walled structure with complex cross-sections and body skeleton performance through multi-level progressive cross-section matching transformation and optimization. A body skeleton model with actual complex cross-sections was established, and compared with the initial simplified structure, the weight reduction ratio of the body skeleton was up to 6.9 %, and the performance indicators of the body skeleton fully met the design requirements, which verified the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This study investigates the seismic performance of built-up steel tubular (BST) columns composed of four mild-steel plates welded to four ultrahigh-strength steel (UHSS) tubes of Grade 1200, presenting a novel concept in column construction. The focus of this research is to evaluate the behavior of these columns under six degrees-of-freedom (6DOF) boundary conditions, replicating realistic loads induced by seismic events. A comprehensive experimental program was carried out at Swinburne University of Technology, including quasi-static (QS) cyclic and hybrid simulation (HS) tests. These experiments aimed to monitor the progression of physical damage and assess the hysteresis response of the columns, providing valuable insights into their stiffness, strength, and energy absorption capabilities. The results demonstrate the columns' reasonable seismic performance, indicating their potential use in ordinary moment-resisting frames within regions experiencing low–moderate seismic activity. [ABSTRACT FROM AUTHOR]

Significant advancements have been made in the area of composite structures. Aligned with an innovative design, the motivation behind this research is, first, to make efficient use of timber as an environmentally friendly material and, second, to employ steel alongside timber effectively to prevent buckling of the steel. This research aims to bridge this knowledge gap by exploring the integration of steel, carbon fiber–reinforced polymer (CFRP), and timber. The objective is to create innovative composite column structures that leverage the unique properties of each material to enhance structural performance and efficiency. The authors conducted tests on a set of 24 columns under compression conditions. The results of the structural tests demonstrated significant compression capacities relative to their mass, highlighting the significant advantages of material synergy within these elements. The study thoroughly quantifies these benefits, shedding light on the potentially transformative impact of these innovative composite columns in the field of structural engineering. A significant finding was the influence of the timber section's geometry on preventing column buckling. Furthermore, the positioning of steel within the sandwich columns played a vital role, with steel elements having a greater area with timber exhibiting enhanced structural performance and reduced likelihood of debonding. This paper introduces a new parameter, the inelastic transition area denoted as INT±70% peak , which characterizes the smoothness or abruptness of the transition once the inelastic region begins and the graph descends. This parameter bears significance in risk analysis for structures susceptible to progressive failure. All specimens displaying substantial energy absorption featured larger timber sections, highlighting the pivotal role of timber in absorbing higher levels of energy during structural loading. The findings contribute to the growing body of knowledge on composite materials and their applications in modern construction. [ABSTRACT FROM AUTHOR]

The dynamic stress–strain response of a material can be described by a number of different models of varying fidelity. However, an individual model's ability to replicate the dynamic stress–strain response of a material can be hindered by experimental variability. Reification, an approach to fusing models and experimental data with inherent scatter, is presented. It is then used to determine the optimum parameters of the Johnson–Cook (JC) and Zerilli–Armstrong (ZA) models using a fusion of Split-Hopkinson Pressure Bar (SHPB) data and the JC and ZA models fit to the SHPB data using a traditional approach. The output of the fused model is a dataset that represents a "best-guess" sampling of the possible stress–strain response of a high strength steel. In the present work, the dynamic response of a newly developed steel, AF9628, is evaluated. Under the reification framework, the experimental variability and limitations of the mathematical model expressions are addressed by the optimized sampling of data and combined fitting process. The JC and ZA models are then re-fit to partitions of the fused dataset, which bound the responses of the traditionally fit JC and ZA models. The behavior of the re-fit models and the traditionally fit models are compared via a simulated Taylor anvil test. [ABSTRACT FROM AUTHOR]

High-carbon hardline steels are primarily used for the manufacture of tire beads for both automobiles and aircraft, and vanadium (V) microalloying is an important means of adjusting the microstructure of high-carbon hardline steels. Using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM), the microstructure and precipitation phases of continuous cooled high-carbon steels were characterized, and the vanadium content, carbon diffusion coefficient, and critical precipitation temperature were calculated. The results showed that as the V content increased to 0.06 wt.%, the interlamellar spacing (ILS) of the pearlite in the experimental steel decreased to 0.110 μm, and the carbon diffusion coefficient in the experimental steel decreased to 0.98 × 10−3 cm2·s−1. The pearlite content in the experimental steel with 0.02 wt.% V reached its maximum at a cooling rate of 5 °C·s−1, and a small amount of bainite was observed in the experimental steel at a cooling rate of 10 °C·s−1. The precipitated phase was VC with a diameter of ~24.73 nm, and the misfit between ferrite and VC was 5.02%, forming a semi-coherent interface between the two. Atoms gradually adjust their positions to allow the growth of VC along the ferrite direction. As the V content increased to 0.06 wt.%, the precipitation-temperature-time curve (PTT) shifted to the left, and the critical nucleation temperature for homogeneous nucleation, grain boundary nucleation, and dislocation line nucleation increased from 570.6, 676.9, and 692.4 °C to 634.6, 748.5, and 755.5 °C, respectively. [ABSTRACT FROM AUTHOR]

Detrital zircon (DZ) geochronology is based on a multistage, hierarchical sampling process in which sampling errors (statistical variance) and non-sampling errors (sampling bias) are endemic. Most of these errors are related to 1) initial collection of a non-random grab sample (typically from outcrop); 2) processing the grab sample to obtain a non-random grain-size sample of restricted grain size(s) (effectively a processed population); 3) randomly and/or non-randomly selecting DZs (often based on their size, shape, and colour) from the grain-size sample to obtain a hand-picked sample (effectively an analysed population); and 4) randomly and/or non-randomly radiometrically dating only certain DZs (due to limitations of instrument spot size and grain imperfections) from the hand-picked sample to obtain an analysed sample. Claims that hand-picked samples and analysed samples are randomly chosen are questionable, since these samples likely represent haphazard sampling attempting to emulate randomness. Non-randomness has major implications for calculations that determine sample size and inter-sample 'sameness' comparison, as both techniques generally depend on randomly chosen samples. The use of inter-sample comparison is particularly troublesome in that sameness is determined for the analysed sample, which is not representative of the initial grab sample. Yet more bias occurs with a 'leap of inference', the generalization of DZ ages from the analysed sample to the target population (the strata of interest) or to a general population (DZs derived from ultimate and proximate sources). Sampling bias can be reduced by unambiguously defining the sampled population (the population that inferential statistics apply), selecting representative samples (if possible, randomization should be used at every stage in the sampling process), and preserving the representativeness of subsamples by using correct sampling devices such as a microsplitter. It may be timely for standardized sampling, interpreting, and reporting guidelines so that detrital geochronology data are scientifically meaningful and replicable. [ABSTRACT FROM AUTHOR]

Cutin, one of the main structural components of tomato peels, is a waxy biopolymer rich in hydroxylated fatty acids. In this study, 10,16-dihydroxyhexadecanoic acid (10,16-diHHDA) was extracted and isolated from tomato peels and exploited to develop fully crosslinked polyesters as potential candidates for replacing fossil-based metal protective coatings. A preliminary screening was conducted to select the base formulation, and then a design of experiments (DoE) was used as a methodology to identify the optimal composition to develop a suitable coating material. Different formulations containing 10,16-diHHDA and other biorefinery monomers, including 2,5-furandicarboxylic acid, were considered. To this end, all polyesters were characterized through differential scanning calorimetry (DSC) and gel content measurements to determine their Tg value and crosslinking efficiency. Compositions exhibiting the best trade-off between Tg value, chemical resistance, and sufficiently high 10,16-diHHDA content between 39 and 48 wt.% were used to prepare model coatings that were characterized for assessing their wettability, scratch hardness, chemical resistance, and adhesion to metal substrates. These polyester coatings showed a Tg in the range of 45–55 °C, a hydrophobic behavior with a water contact angle of around 100°, a good solvent resistance (>100 MEK double rubs), and an adhesion strength to steel higher than 2 MPa. The results obtained confirmed the potential of cutin-based resins as coatings for metal protection, meeting the requirements for ensuring physicochemical properties of the final product, as well as for optimizing the valorization of such an abundant agri-food waste as tomato peels. [ABSTRACT FROM AUTHOR]

Although research has shown a considerable influence of the pre-cracking phenomenon on steel-congested concrete members, only normal concrete (NC) has been considered in the literature. The intention in this paper is thus to study the effect of the pre-cracking phenomenon on the bond response of pre-cracked NC with different slump flow values and self-consolidating concrete (SCC). Initial crack widths ranging from 0.0 to 0.5 mm are studied. Results show that initial crack widths larger than 0.10 mm have a significant influence on bond properties, such that reduction factors greater than 30% and 50% are obtained for the maximum bond strength of concrete specimens exposed to initial crack widths of 0.2 mm and 0.4 mm, respectively. Results show that concrete mixtures with higher workability are less sensitive to the pre-cracking phenomenon as compared to NC mixtures. The average bond stress of steel rebar in the pre-cracked SCC is found to be similar to that of the NC with a slump flow of 200 mm, which is considerably better than for NC with a slump flow of 97 mm. Moreover, results show that 65.8, 80.6, 88.5 and 93.1% fracture energy reductions are obtained for crack widths of 0.20, 0.30, 0.40 and 0.50 mm, respectively, as compared to the small crack width of 0.15 mm. [ABSTRACT FROM AUTHOR]

In this paper, the corrosion environment of a railway coal truck was simulated with 1.0%H2SO4 + 3%NaCl solution. The effect of weld toe Tungsten Inert Gas (TIG) remelting on the microstructure and corrosion resistance of welded joints of Q450NQR1 high-strength weathering steel was studied. The results show that the weld toe melts to form a remelting area after TIG remelting. After TIG remelting, the weld geometry was improved, and the stress concentration factor decreased from 1.17 to 1.06 at the weld toe, a decrease of 9.4%. TIG remelting refines the microstructure of the weld toe and improves the corrosion resistance of the welded joint. The surface of the TIG-remelted sample is uniformly corroded with no "deep and narrow" pits after the removal of corrosion products. The weight loss rate and corrosion rate of remelted welds are lower than those of unremelted welds. The structure of corrosion products is loose at the initial stage of corrosion, and the corrosion products are transformed into Fe3O4 and Fe2O3 protective rust layers with a dense structure after 480 h of corrosion. With the extension of corrosion time, the tensile strength and percentage elongation of the specimen decreased linearly. The decreasing rates of tensile strength of remelted and unremelted specimens were 0.09 and 0.11, respectively, and the decreasing rates of elongation after fracture were 0.0061 and 0.0076, respectively. [ABSTRACT FROM AUTHOR]

The influence of varying the manganese (Mn) contents of high-strength copper-containing hull steel on its microstructural evolution and mechanical properties was investigated. With increasing Mn content from 2 to 5%, the tensile strength of the steel increased by ~100 MPa, while the elongation of steel remained at ~23.5%, indicating good plasticity. However, the 2Mn sample had 128 J higher low-temperature (−84 °C) impact work than the 5Mn sample. The microstructures of different Mn steels were composed of fresh martensite (FM), ferrite/tempered martensite (F/TM), and reversed austenite (RA). The increase in Mn content markedly increased the presence of RA and intensified the work hardening caused by the transformation-induced plasticity (TRIP) effect during the tensile process. However, as the phase transformation in different Mn steels occurred in the early stage of strain and did not extend throughout the entire plastic deformation process, increasing plasticity via phase transformation was difficult. In addition, although the volume fraction of RA increased significantly in 4Mn and 5Mn steels, the stability of RA significantly decreased. The presence of numerous metastable blocks and coarse lath-like RA contributed little to low-temperature impact work and was even detrimental to toughness. The substantial fresh martensite resulting from phase transformation facilitated microcrack generation, owing to rapid volume expansion and mutual impacts, thus reducing the work required for crack formation. Additionally, the abundance of deformation twins significantly reduced the work needed for crack propagation. These combined actions significantly reduced the low-temperature toughness of 4Mn and 5Mn steels. [ABSTRACT FROM AUTHOR]

Process maps were developed using a combination of microstructural analysis and DICTRA-based modeling to predict the austenite vol.% as a function of the intercritical annealing parameters and starting microstructure. The maps revealed a strong dependence of the calculated austenite fraction (vol.%) on the Mn content (4–12 wt.%) and intercritical annealing temperatures (600 °C to 740 °C). The calculations were carried out for constant carbon, Al, and Si contents of 0.2 wt.%, 1.5 wt.%, and 1.0 wt.%, respectively. A modified empirical equation proposed by Koistinen and Marburger was employed to calculate the room-temperature retained austenite vol.% as a function of the intercritical annealing temperature, including the effect of the austenite composition. The process maps offer valuable insights for designing intercritical treatments of medium-Mn steels, aiding in the optimization of steel properties for automotive applications. [ABSTRACT FROM AUTHOR]

This research proposes a complete analysis of the use of physical vapour deposition coated dies in the sheet metal forming process for high‐strength‐steel sheets. The goal of the proposed approach is to investigate how PVD coatings affect die performance and how that affects the formability and quality of the high‐strength‐steel‐sheets that are made. The finite element analyses are used to simulate and evaluate the mechanical behaviour and deformation characteristics during the forming process. Studies to enhance the forming characteristics of these materials, typically denoted by limiting draw ratio and maximum punch force are required. A reduction in punch force required and improved limiting draw ratio is observed that is attributed to the enhanced contact with friction‐conditions in the die‐sheet interfaces. The experimental results are compared with simulation results from DD3IMP, a code used for deep drawing simulations, and it is evident that the experimental outcomes are analysed well with the simulation results. [ABSTRACT FROM AUTHOR]

To evaluate the possibility of hydrogen storage in depleted gas reservoirs, natural gas storage facilities, aquifers and salt caverns, the applicability of ferritic pearlitic K55 and tempered martensitic L80, both very frequently used as casings and tubings, has been investigated. Materials were investigated by means of high-pressure, high-temperature autoclave tests and analyses of the hydrogen uptake. The autoclave tests were performed on tensile specimens loaded with a spring at 90 % of the specified minimum yield strength, additionally the samples were analysed to determine the hydrogen uptake. Different gas compositions were considered (pure hydrogen, with or without the presence of CO 2 /H 2 S) under a hydrogen partial pressure of 120 bar. The tests were conducted in dry or wet environments. From the results, it can be seen that the hydrogen uptake is low even under the most severe conditions. However, from the mechanical test conducted in this study, it appears that the ferritic pearlitic K55 steel seems to be a suitable pipe material for underground hydrogen storage, and the higher strength steel L80 steel can be used only in non-sour environments (no significant amount of H 2 S in the reservoir, which is a priori the case of underground storages). • Hydrogen uptake from dry pressurized hydrogen up to 120 bar partial pressure is small compared to hydrogen uptake from brine. • Presence of H 2 S in humid environments increases hydrogen uptake substantially but no ruptures occurred. • K55 and L80 are applicable for underground hydrogen storage within the tested conditions. • Constant Load Tests and low cycle fatigue Ripple Load Tests did not result in any failure of K55 and L80 steel. • Normalized K55 takes up slightly more hydrogen than quenched and tempered L80 due to higher corrosion rate. [ABSTRACT FROM AUTHOR]

Herein, the microstructure and mechanical properties of a low‐alloy Cu‐bearing transformation‐induced plasticity (TRIP) steel and their dependence on the processing history are investigated. The distributions of the retained austenite and bainite are found to be dependent on the initial cold‐rolled microstructure, which can be tailored by the preceding hot‐rolling route (unidirectional/cross rolling) and the subsequent cooling rate (furnace/air cooling). Mechanical properties and TRIP effect strongly depend on the initial microstructure, where the air‐cooled sheet shows remarkable mechanical properties; while the cross‐rolled sheet shows isotropic properties. The addition of copper results in an increase in the amount of the retained austenite, enhancement of strength‐ductility balance, and improvement of the hardening behavior of TRIP‐assisted high‐performance steel. [ABSTRACT FROM AUTHOR]

Herein, the effects of Chromium–Molybdenum (Cr–Mo) addition on the microstructural evolution and mechanical properties of medium‐carbon steel after spheroidization annealing are systematically studied through scanning electron microscopy, electron backscatter diffraction, and tensile testing. Cr–Mo addition hinders the proeutectoid ferrite + pearlite transformation, thereby promoting the bainite transformation. Moreover, it refines the pearlite lamellar spacing as well as decreases the average carbide diameter, increases the number of carbides per unit area, and hinders ferrite recrystallization. Compared with those in the B1 steel annealed for 8 h, the size of carbides and their number per unit area in the CM1 steel are 30% lower and 2.2‐fold higher, respectively. Due to finer ferrite grains, smaller carbides, and a higher amount of carbides, the strength of steel improves, and the plasticity slightly reduces after Cr–Mo addition. After 2 h of annealing, the yield strengths of Cr–Mo steels are 77.5–109.5 MPa higher than those of base steels; the elongations are above 20%. The contributions of the strengthening mechanism of steel to the yield strength are as follows (from high to low): grain boundary, precipitation, solid solution, and dislocation strengthening. [ABSTRACT FROM AUTHOR]

In complex networks, important nodes have a significant impact, both functional and structural. From the perspective of data flow pattern detection, the evaluation of the importance of a node in a network, taking into account the role it plays as a transition element in random paths between two other nodes, has important applications in many areas. Advances in complex networks and improved data generation are very important for the growth of computational materials science. The search for patterns of behavior of the elements that make up steels through complex networks can be very useful in understanding their mechanical properties. This work aims to study the influence of the connections between the elements of steel and the impact of these connections on their mechanical properties, more specifically on the yield strength. The patterns found in the results show the significance of the proposed approach for the development of new steel compositions. [ABSTRACT FROM AUTHOR]

This paper proposed a new approach for the strength interaction diagram (N‐M diagram) of FRP strengthened square steel reinforced high strength concrete (SSRHSC) column, considering the influence of the applied load eccentricity on the ultimate conditions of FRP strengthened high‐strength concrete (HSC). The analytical model for the strength interaction diagram of FRP strengthened SSRHSC (FRPS‐SSRHSC) columns, which incorporated the stress–strain models of constitutive materials into the rectangular stress block (RSB) method, was developed and verified against test data. The strength interaction diagrams of FRPS‐SSRHSC columns developed based on the proposed analytical model matched well with the test results, while the strength interaction diagrams developed using available design codes overestimated the experimental strength interaction diagrams. The effect of confinement ratio and longitudinal FRP strengthening on the strength interaction diagrams was examined via parametric analyses. It was found that longitudinal strengthening had a negligible influence on the axial load and bending moment when the axial load was applied at a small eccentricity but had a substantial influence when the axial load was applied at a large eccentricity. [ABSTRACT FROM AUTHOR]

When designing steel members with nonsymmetric cross sections, it is essential to consider twisting effects when performing stability checks via second-order analysis according to the ANSI/AISC 360-22. Existing line-element formulations for nonsymmetric sections are mostly derived based on thin-walled assumptions, leading to an overestimation of member strength due to the inaccurate prediction of member behavior, especially when the cross sections have moderate wall thickness. This paper proposes an efficient line-element method for second-order analysis of steel members with nonsymmetric thick-walled sections considering the warping degree of freedom (DOF) and the twisting effects along with the transverse shear deformations. Additionally, a two-dimensional (2D) finite-element cross section analysis method employing the constant strain triangle (CST) element is developed to calculate the section properties for arbitrary cross sections, including the Wagner and the shear coefficients. The proposed method is implemented in the educational structural analysis software MASTAN2 and verified through two sets of examples. [ABSTRACT FROM AUTHOR]

In this paper, AlSi coatings and AlSiN coatings on 22MB5 high strength steel and MoS 2 coatings on the die steel were prepared by magnetron sputtering respectively. The tribological properties of the coatings were studied from room temperature to 800 °C. The hardness and the bond strength between the coatings and the substrate were also investigated. The experimental results show that AlSi coatings have poor anti-friction behaviors comparing with the steel, and coefficient of friction (CoF) is as 0.2 at room temperature, but 0.8 at 600 °C. The N element was doped into AlSi coatings with FeAl transition layers to improve the tribological performances of the coatings at high temperature. CoF of AlSiN coatings and H13 steel is high. However, AlSiN coatings have excellent wear-resistance. WS 2 coatings were prepared on the surface of the die steel to improve high temperature anti-friction behaviors of AlSiN coatings and H13 steel pin. The experimental results show that WS 2 coatings exhibit good high temperature anti-friction behaviors. Super low friction about 0.003 is achieved at 600 °C. High temperature superlubricity mechanisms of AlSiN coatings and WS 2 coatings are discussed systematically. [ABSTRACT FROM AUTHOR]

In the modern theory of compressed concrete elements, the most attention is paid to longitudinal deformations, whereas transverse ones are rarely considered and just within Poisson's coefficient limits (i.e., elastic concrete behavior in the transverse direction). However, transverse deformations significantly develop beyond the limits corresponding to Poisson's coefficient, where they lead to longitudinal crack initiation and development. In-depth experimental and numerical investigations of transverse deformations in the inelastic stage showed that it is necessary to consider crack propagation. The present study proposes simultaneous consideration of longitudinal and transverse deformations, as well as the appearance of cracks and their widths and depths. This allowed us to obtain a complete compressed concrete element behavior pattern at all performance stages in two types of limit states (based on longitudinal and transverse deformations). Consequently, new ultimate limit states by the depth and width of cracks caused by transverse deformations are proposed to be included in modern design practices and codes. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of Fe–24Mn–10Al–6Ni–1C steels microalloyed by Nb, Mo, and Nb–Mo coaddition in both solid solution and aging states are evaluated. The results show that the addition of Nb, Mo, or Nb–Mo leads to a decrease in austenitic grain size and a suppression in κ‐carbides precipitation during aging. Besides, Mo slightly promotes precipitation of both B2 bands and particles as a ferrite stabilizer. However, Nb and Nb–Mo increase the volume fraction of B2 particles together with decreasing B2 bands due to the formation of NbC and (Nb, Mo)C. The strengths and ductility are improved simultaneously after adding microalloying elements. The coaddition of Nb–Mo achieves a best combination of strength and ductility. After aging, the precipitation of κ‐carbides and B2 leads to a further enhancement in yield strength but a reduction in plasticity for all the experimental steels. Additionally, the effect of Nb/Mo on the strain hardening behavior is also analyzed. [ABSTRACT FROM AUTHOR]

The body constitutes the largest proportion of the total vehicle weight. Recently, increasing efforts have been made towards reducing its weight and improving its crashworthiness. By reducing its weight, fuel consumption will be reduced, and this will also translate into lower CO2 emissions. In terms of safety, vehicle body components use high strength steel which can absorb a substantial amount of impact energy. The present study pays attention to DP 600 and TRIP 400/700 stress–strain characteristics at quasi-static strain rates. The stress–strain characteristics of absorption capacity, stiffness, and deformation resistance force were investigated experimentally by tensile tests, three-point bending tests, and numerical simulations. The results indicate the potential for increasing the absorption capacity, stiffness, and deformation resistance force of the vehicle body's deformable steel components. The present study verified the possibility of replacing physical testing with numerical simulation. A reasonably satisfactory agreement between the experimentally determined stress–strain characteristics and the numerical simulation was achieved, which can reduce the development time of deformable vehicle body components, reduce costs and optimize the selection of materials. The results extend the state of knowledge on the deformation characteristics of high-strength materials and contribute to the optimization of body components in terms of passive safety and weight. [ABSTRACT FROM AUTHOR]

In the case of copper and its alloys, Wire Arc Additive Manufacturing (WAAM) 3D printing technology is mainly used to produce elements for the maritime industry and research has focused on the use of Cu-Al alloys. There is little information devoted to the use of Cu-Ni alloys in this technology, which are also widely used in the maritime industry. In this work, tests were carried out on the microstructure, mechanical properties, and corrosion properties in a 1M NaCl solution of Cu-Ni 90/10 alloy 3D walls printed using the WAAM method. The obtained objects are characterized by a microstructure with elongated column grains and particles of the Ni-Ti phase, hardness in the range of 138–160 HV10, ultimate tensile strength of 495–520 MPa, yield strength of 342–358 MPa, elongation of 16.6–17.9%, and a low average corrosion rate of 7.4 × 10−5 mm/year. The work shows that it is possible to obtain higher mechanical properties of Cu-Ni 90/10 alloy 3D objects produced using the WAAM method compared to cast materials, which opens up the possibility of using this alloy to produce objects with more complex shapes and for use in corrosive working conditions. [ABSTRACT FROM AUTHOR]

Al2O3-forming austenitic steel (AFA steel) is an important candidate material for advanced reactor core components due to its excellent corrosion resistance and high temperature strength. Al is a strong ferrite-forming element. Therefore, it is necessary to increase the Ni content to stabilize austenite. Ni is expensive and highly active, and so increasing the Ni content not only increases the costs but also damages the radiation resistance. Mn is a low-cost austenitic stable element. Its substitution for Ni will not only help to improve the irradiation resistance of austenitic steel, but also reduce the cost. In order to explore the feasibility of Mn-substituted Ni-stabilized austenite in AFA steel, this paper summarized the research progress of Mn-added AFA steels, whilst the research status of traditional Mn-added austenitic steels are also referred to and compared herein. The effect of the addition of Mn on the microstructure and properties of AFA steel was analyzed. The results show that Mn can promote the precipitation of the M23C6 phase and inhibit the precipitation of the B2-NiAl phase and secondary NbC phase. With the increase in Mn content, the strength of AFA steel at room temperature and high temperature decreased slightly, the room temperature elongation increased slightly, while the high temperature elongation and creep resistance decreased obviously. In addition, for austenitic steel free of Al, the addition of Mn will destroy the oxide layer of Cr2O3, which will decrease the oxidation resistance of the steel. But the preliminary study shows that Mn has little effect on the Al2O3 oxide layer. It is worth studying the effect of Mn-substituted Ni on the oxidation resistance of AFA steel. In summary, more efforts are necessary to investigate the optimal Mn content to balance the advantages and disadvantages of introducing Mn instead of Ni. [ABSTRACT FROM AUTHOR]

In this study, different sizes (25, 50, and 75 µm) and volume fractions (1, 2, and 3 wt%) of calcined eggshell particles were utilized to strengthen the Al-Si-Mg alloy. Several experimental runs were conducted to assess the impact of particle size and concentration on both physical properties (density, corrosion, and thermal conductivity) and mechanical properties (hardness, yield strength, impact energy, and modulus of elasticity). The findings revealed significant enhancements in hardness (21 %), yield strength (61 %), modulus of elasticity (43 %), and thermal conductivity (34 %). Conversely, a reduction of 62 % in impact strength and 8 % in density was observed. The corrosion rate displayed an increase from 0 to 16.67 mpy. Analysis using XRD and XRF techniques identified CaO and Al2O3 as the primary constituents of the eggshell. Optical micrographs consistently showed cored (segregated) dendritic structures typical of castings cooled under normal conditions in the Al-Si-Mg composite. SEM micrographs, EDS spectra, and area analyses confirmed a uniform distribution of Calcined Eggshell Particles (CEP) within the composite films. Additionally, an optimal calcination condition for the eggshell particles was determined to be 900 °C for 2.5 h, resulting in a CaO yield of 99.62 %. [ABSTRACT FROM AUTHOR]

Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete (RC) structures. Limited research has been performed to investigate the life-cycle cost (LCC) of coastal bridge piers with nonuniform corrosion using different materials. In this study, a reliability-based design optimization (RBDO) procedure is improved for the design of coastal bridge piers using six groups of commonly used materials, i.e., normal performance concrete (NPC) with black steel (BS) rebar, high strength steel (HSS) rebar, epoxy coated (EC) rebar, and stainless steel (SS) rebar (named NPC-BS, NPC-HSS, NPC-EC, and NPC-SS, respectively), NPC with BS with silane soakage on the pier surface (named NPC-Silane), and high-performance concrete (HPC) with BS rebar (named HPC-BS). First, the RBDO procedure is improved for the design optimization of coastal bridge piers, and a bridge is selected to illustrate the procedure. Then, reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances. Next, the repair time of the pier is predicted based on the time-dependent reliability indices. Finally, the time-dependent LCCs for the pier are obtained for the selection of the optimal design. [ABSTRACT FROM AUTHOR]

This paper reports an experimental on the flexural performance of prestressed concrete-encased high-strength steel beams (PCEHSSBs). To study the applicability of high-strength steel (HSS) in prestressed concrete-encased steel beams (PCESBs), one simply supported prestressed concrete-encased ordinarystrength steel beam (PCEOSSB) and eight simply supported PCEHSSBs were tested under a four-point bending load. The influence of steel strength grade, I-steel ratio, reinforcement ratio and stirrup ratio on the flexural performance of such members was investigated. The test results show that increasing the I-steel grade and I-steel ratio can significantly improve the bearing capacity of PCESB. Increasing the compressive reinforcement ratio of PCEHSSB can effectively improve its bearing capacity and ductility properties, making full use of the performance of HSS in composite beams. Increasing the hoop ratio has a small improvement on the load capacity of the test beams; setting up shear connectors can improve the ductile properties of the specimens although it does not lead to a significant increase in the load capacity of the combined beams. Then, combined with the test data, the comprehensive reinforcement index considering the location of reinforcement was proposed to evaluate the crack resistance of specimens. The relationship between the comprehensive reinforcement index and the crack resistance of specimens was given. [ABSTRACT FROM AUTHOR]

Landslides due to catastrophic weather events, especially heavy rainfall, have risen significantly over the last several decades, causing significant damage and affecting the health and livelihoods of millions of people. Using tree roots to bio-engineer shallow slopes has been proven to be a cost-effective, sustainable measure and thus has gained increasing popularity. As slope failure often occurs under heavy precipitation, it is important to understand the mechanical interactions in the soil matrix surrounding a root to better estimate the reinforcement capacity of a root system, especially as the soil undergoes wetting from drier conditions. However, very few studies of root reinforcements have considered the effects of degree of saturation on behaviour. In this study, steel wires are used as a root analogue to explore the impact of root geometry, soil dilation and soil saturation on the pull-out behaviour of a root and three commonly used unsaturated soil strength models have been used to interpret the pull-out results. It was found that roots with larger diameter did not contribute to additional resistance. Also, a linear relationship between degree of saturation and pull-out strength was identified over a large range of suctions and one of the unsaturated soil strength models seemed to provide a more reasonable interpretation. The results will help future bioengineering slope design by improving the understanding of soil-root interface behaviour, including the effect of root diameter in slippage failure and greater emphasis on the importance of taking degree of saturation into account in unsaturated soil strength models. [ABSTRACT FROM AUTHOR]

Fe-C-Cr-Nb alloy steel surfacing layers with different contents of C and Cr were prepared on 45 steel base metal by selfshielded flux-cored wires with distinct amounts of high carbon chromium iron addition and melt arc surfacing. The composition and microstructure changes of the surfacing layer were tested and analyzed. The surfacing test plate was processed into a pulling specimen, and the bonding strength between the surfacing layer and the 45 steel base metal was tested with a self-designed pulling test method. The fracture location of the pulling specimen and fracture characteristics were observed by a metallurgical microscope and a scanning electron microscope. The result shows that with the increase of the amount of high carbon chromium iron added to flux-cored welding wire, the content of C and Cr in the surfacing layer increases, and the NbC hard phase disperses. The microstructure of the steel matrix changes from mixed martensite + residual austenite to high carbon martensite + residual austenite, and then independent austenite appears. The hardness of the surfacing layer first increases and then decreases. The bonding strength between the surfacing alloy and the 45 steel base metal first decreases and then increases, and the fracture location is at the bottom of the surfacing layer or the fusion zone with mostly quasi-cleavage characteristics. When the additional amount of high carbon chromium iron reaches 13%, thee pulling specimen exhibits significant deformation with the highest bonding strength, and the fracture is close to the fusion line, where there are numerous tearing edges and shallow dimples. [ABSTRACT FROM AUTHOR]

API X70 steel requires high strength and toughness for safety in extreme environments like high pressure and low temperature. Submerged Arc Welding (SAW) is effective for manufacturing thick steel pipes. However, the welding heat input during SAW alters the microstructure and mechanical properties of the heat affected zone (HAZ). Therefore, investigating the correlation between microstructure and mechanical properties in welded X70 pipes is important to address potential degradation of HAZ and weld metal (WM). In this study, post weld heat treatment (PWHT) was performed to improve mechanical properties of HAZ and WM and to reduce residual stress caused by the welding process. We performed PWHT at 640°C for 15 hours and followed by air cooling. After heat treatment, we observed the microstructure through OM and SEM analysis, and investigated the mechanical properties through tensile test, hardness test, and Charpy impact test. [ABSTRACT FROM AUTHOR]

Increasing the operating temperature and pressure of an automotive engine and reducing its weight can improve fuel efficiency and lower carbon dioxide emissions. These can be achieved by changing the engine piston material from conventional aluminum alloy to high-strength heat-resistant steel. American Iron and Steel Institute 4140 modified steels (AISI 4140 Mod.s), which have improved strength, oxidation resistance, and wear resistance at high temperature were developed by adjusting the AISI 4140 alloy compositions and optimizing the heat treatment process for automotive engine applications. In this study, the effects of modifying alloy compositions on the microstructure, mechanical properties (both at room and high temperatures), and oxidation of AISI 4140 Mod.s were investigated. Effective grain refinement occurred due to the influence of high-temperature stable carbide forming elements such as Mo, and V. The bainite structure changed to martensite structure under the influence Cr and Ni. As the Cr and W contents increased, the oxidation resistance was improved, and the oxide layer thickness decreased after 10 hours exposure at 500°C. The AISI 4140 Mod. exhibited a 35% improvement in room temperature strength, 70% improvement in high-temperature strength, and 40% improvement in high-temperature oxidation resistance compared to conventional AISI 4140. [ABSTRACT FROM AUTHOR]

We investigated the influence of steel surface properties on the wettability of zinc (Zn). Our main objective is to address the selective oxidation of solute alloying elements and enhance the wetting behavior of Zn on advanced high strength steel (AHSS) by employing an aluminum (Al) interlayer through the physical vapor deposition technique. The deposition of an Al interlayer resulted in a decrease in contact angle and an increase in spread width as the molten Zn interacted with the Al interlay on the steel substrate. Importantly, the incorporation of an Al interlayer demonstrated a significant improvement in wettability by substantially increasing the work of adhesion compared to the uncoated AHSS substrate. [ABSTRACT FROM AUTHOR]

Ultrahigh-performance concrete (UHPC) is a new cementitious composite material that exhibits a high bond strength with steel reinforcement. To investigate the splice performance levels of steel bars in UHPC, mutual pullout tests on lap-spliced specimens and direct central pullout tests on bond-anchorage specimens were conducted in this work. The main variables included loading mode, concrete cover, and steel bar position. The results showed that the splice strength of lap-spliced steel bars was approximately 0.76 times the bond strength of the anchored steel bar with the same bond length. The splice strengths of specimens under one-way repeated loading were lower than those under monotonic loading; increasing the splice length or concrete cover thickness reduced the weakening effect of one-way repeated loading on lap-spliced specimen performance. The concrete cover thickness showed a strong positive linear correlation with the splice strength in the range of 0.75db to 2.25db and played an important role in stopping crack development in the specimens. The splice strengths decreased when the loading steel bar was moved from the middle of the structure to the side. Based on the experimental results, formulas for the splice strength and critical splice length of lap-spliced steel bars in UHPC under monotonic loading and one-way repeated loading are suggested. Finally, an analytical model for the bond slip of lap-spliced steel bars is proposed, providing a good fit with the test results. [ABSTRACT FROM AUTHOR]