Composite Steel Research Articles

Parametric Investigation of Load-Induced Cross-Frame Fatigue Effects in Composite Steel I-Girder Bridges

Parametric Investigation of Load-Induced Cross-Frame Fatigue Effects in Composite Steel I-Girder Bridges

FEATURES OF THE FORMATION OF THE PHASE COMPOSITION AND PROPERTIES OF HIGH ALLOY STEEL 03Х17Н3Г9МБДЮЧ

Purpose. Evaluation of the influence of alloying elements of corrosion-resistant steel 03Х17Н3Г9МБДЮч on the phase composition and indicators of high-temperature corrosion. Research methods. In order to check the effect of the chemical composition on the structure of steel 03Х17Н3Г9МБДЮч, laboratory steels were made. The production of these steels was carried out in an induction furnace with a main lining with a capacity of 50 kg. The resulting castings were forged into blanks 40 ´ 80 ´100 mm in size, with subsequent hot rolling into samples 25, 20, and 15 mm thick. Determination of the yield strength of steels was carried out after exposure at a temperature of 850 °С for 10,000 hours. The corrosion resistance of the test samples was determined by the gravimetric method after the samples were completely immersed in molten magnesium. Results. The choice of the main alloying elements was justified and their influence on durability in the aggressive environment of the recovery process of spongy titanium production was determined. A thermodynamic calculation of the changed Gibbs energy in the operating temperature range was performed. The required phase ratio of 03Х17Н3Г9МБДЮч steel was considered and selected based on Scheffler de Long and Potak-Sahalevich diagrams. Scientific novelty. The effect of changing the chemical composition of steel 03Х17Н3Г9МБДЮч within technical conditions on the creep limit and durability in the aggressive environment of the recovery process of the production of spongy titanium was determined. Practical value. It is shown that the alloying complex of corrosion-resistant steel is capable of significantly improving the physical, mechanical and technological properties, and expanding the functional application (purpose).

Mesostructured emerging 316L-17-4PH composite steel parts by material extrusion for the property maximization through an efficient microstructural design

Mesostructured emerging 316L-17-4PH composite steel parts by material extrusion for the property maximization through an efficient microstructural design

Influence of layer thickness and heat treatment on microstructure and properties of selective laser melted maraging stainless steel

As one of the main parameters of selective laser melting (SLM) process, layer thickness has a significant impact on the forming performance and efficiency of printed parts. Based on microstructure analysis and properties testing, the metallurgical mechanism, phase composition and mechanical behavior of SLM-formed Corrax stainless steel with different layer thicknesses were discussed. The influence of heat treatment process on the properties was comparatively investigated. The results indicated that at smaller or larger layer thicknesses, the increase in melt dynamic instability and spheroidisation feature easily induced the formation of unfused pore defects, which in turn led to lower relative density and mechanical properties. At the appropriate layer thickness, the suitable melt flow behaviour promoted the formation of good metallurgical bonding between adjacent melt channels. The maximum tensile strength, yield strength and hardness of the samples prepared at a layer thickness of 60 μm were 1224 MPa, 948 MPa and 39.2 HRC, respectively. The microstructure of the as-built samples was martensite and a small amount of austenite. With increasing layer thickness, the cooling rate of the molten pool decreased and the austenite content increased. After solution treatment, the alloying elements dissolved in the martensitic matrix resulted in lower mechanical properties. After aging and solution aging treatment, the mechanical properties were significantly improved due to precipitation strengthening of NiAl nanoparticles and dislocation strengthening. The corresponding tensile strengths were 1655 MPa and 1796 MPa, the yield strengths were 1328 MPa and 1573 MPa, and the hardnesses were 45.7 HRC and 50.2 HRC, respectively.

Simulation of the Evolution of Phase Composition and Austenite Grain Size upon Multi-Pass Hot Deformationof Low-Alloy Steels

The paper presents a model for predicting the structural characteristics and phase composition of low-alloy steels upon hot rolling in the multi-pass deformation mode. The model considers recovery, dynamic, primary, dynamic and static recrystallization of grains, and the normal grain growth, as well as nucleation (including accelerated nucleation during deformation), growth or dissolution, and coarsening of carbonitride particles. The comparison between the calculated results and the experimental data available in the publications shows a satisfactory agreement.

Behavior of GFRP Reinforced-Concrete Bubbled One-Way Slabs by Encased Composite Steel I-Sections

Behavior of GFRP Reinforced-Concrete Bubbled One-Way Slabs by Encased Composite Steel I-Sections

Effect of Electroslag Remelting on the Microstructure and Ballistic Penetration Characteristics of an Austenite‐Based Lightweight Steel

Herein, the effects of electroslag remelting (ESR) and impurities in ESR slag on the composition, microstructure, and properties of lightweight steel with a nominal composition in wt% of Fe‐20Mn‐10Al‐1.5C are studied. These results can provide a reference for the production of such steels using ESR and the design of the composition of such steels. The results show that ESR can make the contents of Si increase and that of S decrease, make the grain size decrease, make the phase transformation of austenite at about 540 °C change from spinodal decomposition to ordered transformation, make the contents of MnS and SiO2 and inclusions greater than 5 μm decrease, make the distribution of inclusions homogenize, and make the shape of inclusions change from long strip with sharp corners to spherical shape. ESR can improve its strength, plasticity, and antiballistic penetration properties.

Three-Dimensional Printing Limitations of Polymers Reinforced with Continuous Stainless Steel Fibres and Curvature Stiffness

This study investigates the printability limitations of 3D-printed continuous 316L stainless steel fibre-reinforced polymer composites obtained using the Materials Extrusion (MEX) technique. The objective was to better understand the geometric printing limitations of composites fabricated using continuous steel fibres, based on a combination of bending stiffness testing and piezoresistive property studies. The 0.5 mm composite filaments used in this study were obtained by co-extruding polylactic acid (PLA), with a 316 L stainless steel fibre (SSF) bundle. The composite printability limitations were evaluated by the printing of a series of ’teardrop’ shaped geometries with angles in the range from 5° to 90° and radii between 2 and 20 mm. The morphology and dimensional measurements of the resulting PLA-SSF prints were evaluated using μCT scanning, optical microscopy, and calliper measurements. Sample sets were compared and statistically examined to evaluate the repeatability, turning ability, and geometrical print limitations, along with dimensional fluctuations between designed and as-printed structures. Comparisons of the curvature bending stiffness were made with the PLA-only polymer and with 3D-printed nylon-reinforced short and long carbon fibre composites. It was demonstrated that the stainless steel composites exhibited an increase in bending stiffness at smaller radii. The change in piezoresistance response of the PLA-SSF with load applied during the curvature bending stiffness testing demonstrated that the 3D-printed composites may have the potential for use as structural health monitoring sensors.

Rapid design method for composite emergency steel piers with thin-walled steel tube framework and discussion on "temporary-permanent" transition

To address the conflict between the reserve of repair materials for existing bridge piers and the demands for emergency repairs, as well as the challenge of converting temporary emergency structures into permanent ones without significant disassembly, a novel composite emergency steel pier has been developed. This pier utilizes commonly available thin-walled steel tube sections as the framework, I-beams as the connecting elements, and incorporates a "temporary-permanent" transition function. Taking the emergency steel pier for medium-height bridge piers in high-speed rail systems as an example, this study introduces three evaluation metrics—security coefficient (n), stability coefficient k), and variation coefficient (V)—analyzing the factors influencing the design and application thresholds of the emergency steel piers from perspectives of strength, stability, and load distribution uniformity. Based on this, a rapid design method for composite emergency steel piers with thin-walled steel tube frameworks that does not require numerical simulation has been developed and experimentally validated. Research findings indicate that when used for the emergency repair of medium-height or lower bridge piers in high-speed railways, the column line stiffness of the thin-walled steel tube framework composite emergency steel piers should range between 0.34 × 10 exp7 kN/mm to 4.15 × 10 exp7 kN/mm. The transverse and longitudinal spacing of the columns should be 1 m to 3 m and 1.5 m to 3 m respectively. The line stiffness of the plinth beams I and II should be greater than 0.69 kN/mm and 1.01 kN/mm respectively. Within these parameter ranges, the emergency steel pier will not experience strength failure or instability, and the load distribution among the columns remains uniformly favorable. In applications to other scenarios, the rapid generation of composite emergency steel piers with thin-walled steel tube frameworks can be achieved by following three steps: parameter selection and structural configuration determination, calculation of the pier-beam linear stiffness ratio, and criterion-based result verification. The rapid design and implementation of composite emergency steel piers help alleviate the contradiction between material stockpiling and repair demands. Furthermore, the pre-designed "temporary-permanent" transition functionality facilitates integrated operations for emergency repairs and permanent restorations.

In situ assembly enabling adhesive-free bonding of large area electronic sensors to concrete for structural health monitoring

Abstract Cracks developed in concrete infrastructure are one of the primary mechanisms that degrade their structural integrity, which may result in structural failures. Previous research on soft elastomeric capacitors (SEC) has shown their viability for structural health monitoring of structural materials, including concrete, steel, and fiberglass composites. The SEC, or its derivative version with a corrugated geometry termed corrugated SEC or cSEC, is a parallel plate capacitor. Prior work demonstrated that it was possible to directly paint the electrode interfacing with the structural material onto the structure and adhere the rest of the pre-fabricated sensor onto the wet interface, thereby eliminating the need for a joining epoxy. This demonstration was conducted on steel and fiberglass. The study on concrete was left to future work as concrete exhibits a much rougher surface and structure/sensor capacitive coupling, causing a significant amplification in signal noise. This study advances structural health monitoring in concrete applications by investigating the in situ assembly of the SEC on concrete where the carbon black (CB)-based electrode plate of the cSEC is directly painted onto the concrete surface and serves as both the adhesive and electrode for the sensor. A series of free-vibration and compression tests were designed and conducted to evaluate the sensing performance of in situ assembled cSEC compared to that of an epoxy-bonded cSEC. Additionally, the bonding strength of the in situ assembled and epoxy-bonded cSEC is evaluated through a peel test. Results show good strain sensing capabilities of the in situ assembled SEC with an R 2 value of 0.986 and a resolution of 45 ± μ ε . Even though the epoxied cSEC demonstrated a higher bonding strength than the in situ assembled cSEC, the in situ assembled cSEC demonstrated adequate bonding strength for the application. This research contributes to the scientific understanding of sensor adhesion and opens avenues for practical applications in infrastructure monitoring, potentially leading to more resilient and sustainable urban environments.

Lateral performance of circular wooden columns reinforced with high-performance bamboo-based composite

This study researches the lateral performance of wooden columns strengthened with the non-damage reinforcement method, which used high-performance bamboo-based composite (HPBBC) materials and steel strips to form a hollow reinforcement system and then jacketed and reinforced the wooden columns. Six wooden columns strengthened by non-damage reinforcing methods were subjected to low cyclic loading tests under horizontal loads with a constant axial pressure ratio. The horizontal loads, displacements, and strain distributions of different locations at the column root were measured. The experimental results showed that the reinforcement method improved the lateral performance of wooden columns by about 4.96–58.54 %. Owing to the protective effect of the reinforcement system, the development of tensile damage to the wooden columns was delayed, but the breaking location was still the column root. In addition, the energy dissipation capacity and equivalent viscous damping coefficient of the reinforced wooden columns were significantly improved. The deformation of the strengthened column root conforms to the plane section assumption, while the deformation of the reinforcement system was lagged due to the absence of colloid and shear connectors between the wooden column and the reinforcement system. A bending capacity equation for the reinforced wood column was deduced based on the strain distribution in the damaged section. The error between the calculated and experimental results was within 13 %.

Comparison study on SMC and grain-oriented laminated steel core for small-size axial flux permanent-magnet synchronous machines

Abstract This study aims to compare the soft magnetic composite (SMC) and grain-oriented (GO) steel stator axial flux permanent-magnet synchronous machine (AFPMSM) in terms of performance and iron losses. Stator cores are manufactured using both materials to perform experimental performance tests. The produced machines are designed for pump propulsion systems in left ventricular assist devices as an application area. The machines are modeled with several analytical equations, and iron losses and performance tests are carried out with AFPMSMs, finite element methods, and experimental setups. Our findings show that the torque density is higher in the GO steel stator AFPMSMs that can produce 15.07 percent more torque. GO steel material experimentally has 20.33 percent less iron loss as SMC material since the loss value per kilogram for SMC material is higher than that for GO steel. In addition, the saturation value of the SMC material is lower than that of the GO material according to the magnetic flux density value.

Experimental study of composite cold-formed steel and timber flooring systems with innovative shear connectors

An experimental investigation into the structural response of cold-formed steel-timber composite flooring systems with innovative and irregularly spaced shear connectors is presented in this paper. Five composite beam tests and a series of supporting material and push-out tests were carried out. The obtained results showed that the innovative shear connectors enabled the generation of considerable composite action, resulting in up to about 45% increases in load-carrying capacity and 15% and 20% increases in the initial and mid-range stiffnesses respectively over the non-composite system. Methods for predicting the effective flexural stiffness and moment capacity of the examined cold-formed steel-timber composite beams are presented and validated against the derived physical test data. It is shown that accurate predictions for both the flexural stiffness and moment capacity can be obtained, with mean prediction-to-test ratios of 0.93 and 0.91 respectively.

Preparation and properties of ZTA/alloyed high manganese steel composites

In the long-term use of high manganese steels, it is not desirable to achieve wear resistance by austenite deformation strengthening alone. The wear resistance of high manganese steel is much lower than that of ordinary wear-resistant steel under medium and low stress conditions. Improving the instability of wear resistance caused by defects in high manganese steels is an important problem to be solved in current industrial production. In this study, a new type of high manganese alloy with high hardness and high wear resistance was prepared by multi-alloying with Cr-W-Mo elements on the basis of 20Mn1.2C. ZTA ceramic particles reinforced high manganese steel composites were prepared by selecting high manganese steel materials with excellent mechanical properties as the metal matrix of ceramic reinforced metal matrix composites. The Cr-W-Mo multi-alloyed high manganese alloys are mainly composed of a mixed austenite and ferrite matrix, M3C-type cementite and M6C-type carbides. The Cr2W6Mo6 sample has the best overall mechanical properties. Its hardness reached 49.8 HRC, which is 1.20 times higher than that of the Cr2 sample. The mass loss was 0.2571 g, which is 79.92% of the Cr16 sample (0.3217 g). The ZTA ceramic particles were well composited with the alloyed high manganese steel matrix, and the thickness of the interfacial layer was 20-30 μm, with the formation of Mn2AlO4 and (Fe, Mn)2SiO4, and (Al, Cr)2O3 in the interfacial layer. The best abrasion resistance was obtained at a ZTA content of 40 vol.%. The mass loss was 0.1669 g, which is 51.88% of the Cr16 material (0.3217 g).

Impact of CO2 as an oxidant on the decarburization and chromium retention and an approach for CO2 recycling

This study explores the unique role of CO2 as an oxidant in stainless steel smelting, focusing on its effectiveness in decarbonization and chromium retention. The research begins by theoretically demonstrating that although the introduction of CO2 increases the CO partial pressure in the reaction system, the decarburization and chromium (Cr) retention capabilities of CO2 can still be stably maintained through the rational adjustment of the molten steel composition, temperature, and inert gas proportions. Further experimental findings indicate that chromium does not exhibit significant oxidation losses when the carbon (C) content exceeds 1.0% (mass). Finally, a novel CO2 recovery and utilization approach is proposed, integrating CO2 capture from smelting flue gas and recycling it for smelting, reducing O2 consumption and energy costs. This innovative process, compatible with existing smelting plants, presents a promising pathway towards carbon neutrality in the iron and steel industry, bridging theoretical insights with practical applications.

Ab initio informed solute drag assessment for ferritic steels

Linking atomistic information on solute interactions with microstructure evolution is a key challenge for predictive modelling of chemistry effects on material properties. The objective of the present work is to provide a link between grain boundary segregation energies with GB migration kinetics on the example of recrystallization in multi-component ferritic steels. For that purpose, the segregation of 64 elements from the periodic table to a representative grain boundary is computed with ab initio density functional theory. To connect this data to grain boundary migration kinetics, the solute trend parameter from a simplified solute drag treatment is employed. The solute trend parameter for individual solutes is presented, which highlights solutes with large impact on grain boundary migration. Furthermore, an extension of the solute trend parameter is introduced that allows to evaluate the solute drag potential of realistic steel compositions. The necessity to include solute co-segregation, site competition, and precipitation effects is shown in a comparison to experimental data on recrystallization kinetics. The comparison to experimental data demonstrates the qualitative predictability of recrystallization kinetics by the extended solute trend parameter.

Analytical Investigation of Fatigue Behavior in a Modified Composite Steel Box Concrete Girder Bridge with Corrugated Steel Webs under Pavement and Expansion Joint Deterioration

Analytical Investigation of Fatigue Behavior in a Modified Composite Steel Box Concrete Girder Bridge with Corrugated Steel Webs under Pavement and Expansion Joint Deterioration

The influence of 3D printing mode on the chemical composition and structure of 30HGSA steel

The authors carried out the study of the influence of 3D printing modes on the structure and chemical composition of 30HGSA steel (chromansil) samples produced by the method of additive electric arc surfacing. To study the influence of the electric arc surfacing mode on the chemical composition of the steel under study, an optical emission analysis of the samples was carried out. The influence of the surfacing mode on the resulting structure was assessed over the entire height of the deposited walls at magnifications of ×50, ×100, ×200 and ×500. Optical emission analysis identified a change in the material chemical composition associated with the loss of chemical elements. It was found that the degree of loss of C, Cr and Si increases almost linearly and is directly proportional to the surfacing heat input (Q, J/mm). The exact influence of an increase in the surfacing heat input on the Mn content was not found, but a relationship between the degree of its loss and the voltage (U, V) during surfacing of samples was identified. Microstructural studies of all samples did not reveal a large number of systemically formed structural defects characteristic of cast and welded products (pores, shrinkage cavities, etc.), which confirms the high quality of the metal in goods produced by electric arc surfacing. Analysis of micrographs taken in different areas of the samples allowed determining that the metal microstructure does not undergo significant changes under different surfacing modes; the main tendencies in changes in the structure along the height of the sample are preserved. All samples demonstrated the formation of a highly dispersed structure, regardless of the 3D printing parameters. The most favorable metal structure, suitable for subsequent use in the production of goods using additive manufacturing, was recognized as the structure of the sample deposited using mode No.5 (I=160A, U=24V, Q=921.6J/mm). This mode can be used for further study of the problems of additive electric arc surfacing of 30HGSA steel.

Enhancing road safety with the infrastructure-adaptable NDBA 2.0 concrete median barrier: An Italian experience

Road safety is a crucial global concern because of the high number of fatalities and injuries resulting from road crashes each year. Median crossover collisions are among the most dangerous crashes that happen on highways, frequently leading to serious or fatal injuries. The main approach to decreasing the occurrence of these types of crashes is the installation of median barriers. When the need for such installations arises, road agencies must choose from various options, including concrete barriers, cable barriers, or metal-beam guardrails. This paper is dedicated to the New Dynamic Barrier for Highways (NDBA 2.0), an innovative technology for median barriers developed by the Italian National Road Agency (ANAS), emphasizing its pivotal role in enhancing road safety. It incorporates high-tensile steel and advanced composites, offering robust protection while maintaining a lightweight profile. What distinguishes the NDBA 2.0 is its dynamic nature, featuring an intelligent system that seamlessly adapts to the road infrastructure. Its modular construction, with sections of only 200 cm, allows for easy installation and ensures compatibility across successive road segments. This adaptability reduces construction time while maintaining the highest standards of performance. From a road safety perspective, the NDBA 2.0 offers substantial advantages. Its design contributes to minimizing crash-related costs by reducing the severity of crashes, particularly in the transition zones. The barrier's design allows it to adapt to varying road conditions and traffic volumes, effectively addressing common installation challenges on existing roadways as well. Its ability to be directly supported on the road surface wear layer eliminates the need for costly foundation structures, facilitating quick installation and reducing maintenance expenses. The NDBA 2.0 barrier was designed to eliminate the need for future simulations in the design and verification of transitions between different barriers. For this reason, the NDBA 2.0 barrier has been tested in real-world conditions in class H4 and, consequently, is equipped with CE marking. This study offers a comprehensive analysis of the NDBA 2.0 barrier, whose implementation may provide significant benefits for road safety. Continued research, collaboration, and widespread adoption of the NDBA 2.0 barrier can further enhance road safety on a global scale.

STUDY OF THE INFLUENCE OF THE CHEMICAL COMPOSITION OF RAILWAY AXLE STEEL ON THE UNIFORMITY OF THE FINAL MICROSTRUCTURE

The relevance of the work. For modern railway transport, increasing the strength and operational reliability of rolling stock parts, in particular railway axles, is an urgent task. It is known that the inhomogeneity of the distribution of chemical elements in the structure of structural grade carbon steels is formed mainly during their crystallization and may subsequently affect the final structural state and set of properties. Purpose. Study of the influence of the chemical composition of steels for railway axles on the uniformity of the structure. Methodology. Experimental ingots of different chemical compositions with different amounts and ratios of the main chemical elements within the range of OS and EA1N were produced in laboratory conditions. The grain structure was studied on microsections after etching with nital. Chemical inhomogeneity (“traces” of the dendritic structure) − the distribution of chemical elements in the microstructure of cast samples was detected by etching in a hot solution of sodium picrate. Metallographic analysis was performed on a light (optical) microscope “Axiovert 200 M MAT” manufactured by “Carl Zeiss”. The results. The effect of changing the chemical composition of carbon steel, which is intended for the manufacture of railway axles, on the peculiarities of the formation of ferrite-pearlite heterogeneity and grain size is determined. It is shown that in samples of steels corresponding to the EA1N brand with a lower carbon content, the distribution of phases is uneven. The mechanism of formation of such a structure is explained from the point of view of two theories. In samples of steels with an average carbon content, which correspond to steel of the OS grade, the distribution of the pearlite and ferrite phases is more uniform, the relationship between the size and the degree of darkening of the pearlite areas with the order of the former dendritic branches has been established. Based on the results of the quantitative analysis of the final grain structure, it was established that OS steel with an average carbon content at different Mn/Si ratios has a more uniform grain structure. EA1N steel with a lower carbon content has a pronounced grain size, with an increase in the Mn/Si ratio, the largest maximum of the dependence of the distribution shifts to a larger grain size (smaller number). Practical results. Increasing the homogeneity of the final microstructure contributes to increasing the plasticity and viscosity of steel, which directly affects the reliability and durability of railway axles.