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In response to the intensifying competition in the mold market and the increasingly stringent specifications of die forgings, the existing 55NiCrMoV7 (MES 1 steel) material can no longer meet the elevated demands of customers. Consequently, this study systematically optimizes the alloy composition of MES 1 steel by precisely adjusting the molybdenum (Mo) and vanadium (V) contents. The primary objective is to significantly enhance the microstructure and thermal–mechanical fatigue performance of the steel, thereby developing a high-performance, long-life hot working die steel designated as MES 2 steel. The thermal–mechanical fatigue (TMF) tests of two test steels were conducted in reverse mechanical strain control at 0.6% and 1.0% strain levels by a TMF servo-hydraulic testing system (MTS). The microstructures of the two steels were characterized using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results indicate that throughout the entire thermomechanical fatigue cycle, both steels exhibit initial hardening during the low-temperature half-cycle (tension half-cycle) and subsequent continuous softening during the high-temperature half-cycle (compression half-cycle). Furthermore, under the same strain condition, the cumulative cyclic softening damage of MES 1 steel is more pronounced than that of the newly developed MES 2 steel. The number, width, and length of cracks in MES 2 steel are smaller than those in MES 1 steel, and the thermomechanical fatigue life of MES 2 steel is significantly longer than that of MES 1 steel. The microstructures show that the main precipitate phase in MES 1 steel is Cr-dominated rod-shaped carbide. It presents obvious coarsening and is prone to inducing stress concentration, thus facilitating crack initiation and propagation. The precipitate phase in MES 2 steel is mainly MC carbide containing Mo and V. It has a high thermal activation energy and is dispersed in the matrix in the form of particles, pinning dislocations and grain boundaries. This effectively delays the reduction in dislocation density and grain growth, thus contributing positively to the improvement in thermomechanical fatigue performance. [ABSTRACT FROM AUTHOR]

The control of the technical condition of the lifting steel ropes is important for the safe operation and for the correct functioning of the machines in which they work. Most often, the stresses in the ropes depend on the tension force, the construction and diameter of the rope, the number of wires in the rope, etc. All these factors are important in the control and monitoring of a given lifting rope during operation, to adequately and timely assess the quality of the rope, its remaining operational resource, and from there to assess its working capacity. The research is aimed at evaluating the performance and reliability of a real working wire steel rope intended for the mining industry. The behaviour of a real working rope was followed for different periods of time until it was retired, and results were obtained for its real operational properties, in comparison with those before use. The breaking force and tensile strength of the rope wires, as well as their plasticity, flexibility and resistance to bending throughout the period of in-service monitoring, were determined. [ABSTRACT FROM AUTHOR]

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In laser additive manufacturing (AM) of hot work tool steels, direct tempering (DT) of the tool from as-built (AB) condition without prior conventional austenitization and quenching results in enhanced tempering resistance. To date, intercellular retained austenite (RA) decomposition, leading to a shift in secondary hardening peak temperature, and finer martensite substructure are reported to be responsible for such a behavior. In this work, authors aimed at studying the strengthening contributions by performing isothermal tempering tests for long times (up to 40 hours) at elevated temperatures (up to 650 °C) on DT and quenched and tempered (QT) specimens. The thermal softening kinetics and the microstructural evolution were evaluated with the support of computational thermodynamics. The results suggest that the main contributor to enhanced temper resistance in DT condition is the larger fraction of thermally stable and extremely fine (~ 20 nm) secondary (tempering) V(C,N) compared with QT. This could be explained by the reduction of available V and C in austenitized and quenched martensite for a later secondary V(C,N) precipitation during tempering, because of equilibrium precipitation of relatively large (up to 500 nm) vanadium-rich carbonitrides during the austenitization process. A complementary effect of the substructure refinement (i.e., martensite block width) in rapidly solidified highly supersaturated martensite was also quantified in terms of Hall–Petch strengthening mechanism. The significant effect of secondary V(C,N) was successfully validated by assessing a laser AM processed vanadium-free hot work tool steel in QT and DT condition, where no significant differences in strength and temper resistance between the two conditions were evident. [ABSTRACT FROM AUTHOR]

Steelwork is one of the main emitters of CO2 in the world. For this reason, many efforts are being made to reduce or avoid CO2 emissions by unit optimization or by carbon capture and storage (CCS) or utilization (CCU) processes. In the steelwork, three main off-gases are generated including the Blast Furnace Gas (BFG), the Coke-Oven Gas (COG), and the Basic Oxygen Furnace Gas (BOFG). Different processes and technologies can be proposed for recovery based on the volume and composition of the steelwork off-gases. In this paper, the BFG stream is utilized to improve the efficiency of the GTL process and reduce CO2 emissions. For this purpose, a part of the BFG gases is mixed with the syngas produced in the methane autothermal reforming process and injected into the Fischer-Tropsch reactor to produce liquid hydrocarbons. The BFG flow rate was determined according to the optimum H2/CO value. The pressure and volume of the reactor were set at 10 bar and 300 m3 for optimal hydrocarbon production. The simulation results showed that mixing a portion of the BFG with the syngas increases the C5+ production by 11268 bbl/day, while the CO2 emissions decreased by 146529 ton/yr. [ABSTRACT FROM AUTHOR]

The hot work die steel 4Cr5Mo2V has insufficient high‐temperature strength, making it difficult to meet advanced manufacturing requirements. Herein, a novel modified 4Cr5Mo2V‐Co steel with 0.5% Co addition is designed and subjected to tensile tests at room and high temperature, and the precipitation formation and microstructure evolution are characterized by optical microscopy, scanning electron microscopy, electron backscatter diffraction, X‐ray diffractometer, and high‐resolution transmission electron microscopy. The results show that Co microalloying increases the strength of 4Cr5Mo2V steel while slightly decreasing its plasticity with temperatures ranging from 25 to 700 °C. The increased high‐temperature strength of 4Cr5Mo2V‐Co steel is mainly attributed to dislocation and precipitation strengthening. This can be attributed to the addition of Co lowering the stacking fault energy of bcc grains, preventing dislocation climb and cross slip, thus increasing the dislocation density. In turn, the dislocations provide more nucleation sites for M2C phase precipitation, promoting more dispersed nanoscale M2C phase formation. During high‐temperature tensile deformation, the recrystallization softening phenomenon of 4Cr5Mo2V steel is more pronounced due to the presence of continuous dynamic recrystallization. [ABSTRACT FROM AUTHOR]

This paper presents the results of a pilot application of Powder-Bed Fusion of Metals Using a Laser (PBF-LB/M) for the fabrication of M300 (1.2709) maraging steel sheet metal bending tools. S235 steel was used as a substrate for the fabrication of bending punches. The main goal of the research was to determine the usability of such tools without heat treatment, which would contribute to the increase in the cost of tool production. Industrial tests of tools were conducted during the forming of Inconel 625 and AW-6061 T0 aluminium alloy sheets. The punches were subjected to tests of surface roughness, hardness, microstructure, porosity, and geometric quality in order to verify the quality and accuracy of tools made by the PBF-LB/M technique before and after experimental investigations in industrial conditions in a selected manufacturing company. It was found that tools with an M300 steel working layer after the PBF-LB/M process without heat treatment show suitability for bending sheet metal in a certain range of force parameters, ensuring obtaining elements after bending from Inconel 625 and AW-6061 T0 aluminium alloy sheets of the required geometric quality. [ABSTRACT FROM AUTHOR]

This is a study of the cooperative work of making steel in a contemporary steel plant. The study is, first of all, a study of the coordinative practices of a cooperative ensemble of operators controlling a time-critical transformation process, while spatially dispersed at different work stations across the plant, working under quite different and varying local constraints and requirements, with only rudimentary means of ongoing communication. Their individual and local contributions to the overall effort must be minutely synchronized to meet the strict temporal requirements of the operation as a whole. These challenges notwithstanding, the operators manage to act concertedly to produce quality steel and to do so routinely. The question is, how do they manage to do that? As the workers in the setting generally are not able to coordinate their cooperative effort discursively, it is analytically both feasible and necessary to foreground and identify the knowledge of metallurgy of steel and of the plant that enables them, as they go about their own local activities, to apprehend the problems and intentions of their colleagues as reflected in the changing state of the technical processes. The underlying thesis of the study is that in order to answer the general question of how workers engaged in cooperative work are able to heed the activities of their colleagues, and to do so routinely, we are well advised to 'take the concept of practice seriously'. [ABSTRACT FROM AUTHOR]

This study examines the diffusion bonding of 316 L stainless steel and H13 hot work tool steel, aiming to optimize process parameters and assess the resulting microstructural and mechanical properties. Both materials were bonded at varying temperatures (700, 750, and 850 °C) and times (15, 30, and 60 min). The joints are analyzed using scanning electron microscopy (SEM), energy‐dispersive spectroscopy, and X‐ray diffraction (XRD) to evaluate interfacial morphology, chemical composition, and phase formation. Microhardness measurements indicate an increase in hardness from the 316 L side to the H13 side, suggesting intermetallic phase formation. Shear strength tests show the highest strength at 850 °C for 30 min, with longer times leading to strength reduction due to brittle intermetallic compounds. SEM analysis reveals improved bonding interfaces with fewer voids at higher temperatures and longer times, but the Kirkendall effect causes void formation, negatively impacting mechanical properties. XRD confirms α‐Fe and γ‐Ni phases, with Fe3C forming at 850 °C for 60 min. This study underscores the importance of process parameters in optimizing joint properties and minimizing brittle phase formation, providing insights for industrial applications requiring robust and corrosion‐resistant joints. [ABSTRACT FROM AUTHOR]

The article presents the classification of the wear mechanisms of forging tools. The durability of dies can be enhanced through a variety of methods, including the selection of appropriate hot working tool steel, the application of effective heat treatment, the utilization of advanced surface engineering techniques, and the incorporation of lubricating and cooling agents. Two popular methods of tool regeneration, such as re-profiling and laser regeneration, are presented. The issue of numerical wear prediction based on the Archard model, the correlation of this model with experimental results, low-cycle fatigue (HTLCF), and an alternative method based on artificial neural networks are discussed. The paper aims to present currently known wear mechanisms and the methods of increasing and predicting tool durability. [ABSTRACT FROM AUTHOR]

Shafts play a key role in the operation of mining plants. They connect underground excavations with the surface and provide the ability to transport people, equipment, and raw materials. The nature of the dynamic interaction of a conveyance moving at a significant speed along deformed guide rails is complex, and the method of assessing the interaction of hoisting conveyances with shaft steelwork, despite ongoing research, still requires further understanding and improvement. Misalignments of the guide rails and conveyance movements transverse to the shaft axis induce impact (guiding) forces, which are the key design parameters of shaft steelwork. The reliable assessment of guiding forces allows the design of safe and economical steelworks and the assessment of their structural safety during operation under deformations and corrosive deterioration. Determining the value of guiding forces requires their field measurements or the use of approximate empirical formulas. Both methods have their limitations—measurement is expensive and interferes with normal shaft operation, while empirical formulas are subject to high error due to the lack of consideration of many structural details specific to each shaft that significantly affect the behavior of the system. This study presents a new method for using a relatively simple-to-implement measurement of hoisting conveyance acceleration to assess guiding forces. A finite element model of the skip and steelwork was built, and simulations of the conveyance interaction with the structure were carried out. A strong relationship between the sliding plate's impact point location and the guiding force was found. Extreme values of the guiding force were observed in the vicinity of the bunton connection. The study showed that reducing the skip load mass does not affect the force value. Simplified methods of calculating the moments of inertia of the hoisting conveyance significantly overestimate the code-based values of the guiding forces. The presented method considers the actual stiffness and mass distribution of hoisting conveyance and, therefore, allows for a more accurate estimation of the guiding forces and the transport of larger loads. This data-driven approach allows for the continuous monitoring of the guiding forces, the adjustments of the hoisting parameters, the rational planning of repairs, and a reduction in the replacement of corroded shaft steelwork. [ABSTRACT FROM AUTHOR]

ABSTRACT This study investigates the stress–strain behavior of AISI H13 hot work die steel under thermomechanical fatigue (TMF) conditions. An electromagnetic‐thermal‐mechanical coupled finite element model was established to analyze the temperature and stress evolution during TMF cycles. Experimental results reveal that as TMF cycles increase, the hysteresis loop areas expand, and maximum tensile and compressive stress values decrease, indicating cyclic softening of AISI H13 steel. After undergoing TMF, observations show martensitic lath recovery and carbide coarsening along boundaries. Numerical results indicate thermal cycles cause temperature field inhomogeneity along the axial direction, which leads to a non‐uniform distribution of internal stresses along the longitudinal axis. Besides, the TMF lifetime under numerical simulation is comparable to that obtained through experiments. Based on experimental and simulation data, four life prediction models are employed, with the Ostergren model showing the highest consistency with a reliability factor of 1.2. [ABSTRACT FROM AUTHOR]

In this study, in order to improve the characteristics of the vegetable-based cutting fluids used in the MQL technique and increase the machining performance of MQL and its positive effects on sustainable manufacturing, the effects of the MQL method with nano-Al2O3 additives on surface roughness (Ra) and cutting temperature (Ctt) were examined through turning experiments carried out by adding nano-Al2O3 to the vegetable-based cutting fluid. For this purpose, machining tests were carried out on hot work tool steel alloyed with Cr-Ni-Mo that has a delivery hardness of 45 HRC. In hard machining experiments, three techniques for cooling and lubricating (dry cutting, MQL, and nano-MQL), three cutting speeds (V) (100, 130, 160 m/min), three feed rates (f) (0.10, 0.125, and 0.15 mm/rev), and two different ceramic cutting tools (uncoated and TiN-coated with PVD methods) were used as control factors. For Ra, the nano-MQL method provided an average of 21.49% improvement compared to other cooling methods. For Ctt, this rate increased to 26.7%. In crater wear areas, the nano-MQL method again exhibited the lowest wear values, decreasing performance by approximately 50%. The results of this research showed that the tests conducted using the cooling of nano-MQL approach produced the best results for all output metrics (Ra, Ctt, and crater wear). [ABSTRACT FROM AUTHOR]

Failure analysis was performed on a prematurely failed high-speed steel work roll of a hot strip mill in an integrated steel plant to identify the root cause of failure. Visual observation of the fractured surface revealed that the surface was rough and spalled with no indication of fatigue marks. Microstructure investigation was conducted using an optical microscope and scanning electron microscope (SEM) with energy dispersive x-ray spectroscopy (EDS). The microstructure of the roll comprises MC, M2C and M23C6 carbides in a martensitic matrix. Acicular-shaped, coarse M2C carbides were distributed along the cell boundaries in the microstructure and these carbides escalate the sensitivity for crack propagation and decrease the spalling resistance of work roll during service. X-ray diffraction analysis of failed sample also confirmed the presence of M2C carbides. The microstructure constituents of the failed work roll were compared with the equilibrium solidification diagram generated from the chemical composition by JMat Pro. It is recommended from this study that the precipitation of coarse intercellular M2C carbides in high-speed steel work roll should be controlled by modifying the chemical composition and optimising the solidification/cooling rate. [ABSTRACT FROM AUTHOR]

Electromagnetic stirring is a technique of influencing the crystallization pattern of a continuously cast workpiece and suppressing the development of a number of macrostructural defects in it. In this study, technological schemes are presented for application of electromagnetic fields in continuous-casting machines (CCMs) while discussing the resultant physical effects. We present actual results on the quality of steel obtained using a roller-type EMS system installed in the secondary cooling zone of a slab CCM at Novolipetsk Iron and Steel Work. [ABSTRACT FROM AUTHOR]

In this study, the effect of machining parameters on the surface roughness value of DIN 1.2343 (X37CrMoV5-1) hot work tool steel with dimensions of 181x131x37 mm used in plastic injection molds of automotive sector lighting products by plunge erosion method was investigated. The experimental work was carried out on an OSCARMAX S430S PNC (60A) plunge erosion machine with COOLMATIC EDM PLUS erosion fluid. Electrode (CuBe2, CuAl10Ni5Fe4, CuCrZr) with Ø16 mm diameter and 25 mm length, current (4 A,8 A,16 A), on time (30 μs, 60 μs, 120 μs) and off time (45 μs, 90 μs, 180μs) parameters are used in the experiments. With the help of Minitab21 program, L27 orthogonal array was created and experiments were applied. After the experiments, the surface roughness value was measured with Mitutoyo SJ-410 surface roughness measuring device. In line with these values, Taguchi (Least Best) experiment analysis was performed with the help of Minitab21 program. As a result of the analysis, the optimum parameters were determined as CuAl10Ni5Fe4 electrode, 4 A current value, 30 μs on time and 180 μs off time. In the verification experiment performed with these parameters, a surface roughness value of 2.16 µm was obtained. As the smallest surface roughness value obtained as a result of the experiments was 2.16 µm, it is seen that the process parameters were selected optimally. In the last stage of the experimental study, ANOVA analysis performed with the help of Minitab21 program showed that the importance of the parameters for the surface roughness value were on time (39.53%), current (31.02%), off time (10.21%) and electrode type (2.2%), respectively. [ABSTRACT FROM AUTHOR]

In order to evaluate the potential application advantages of static magnetic field on the development of electroslag remelted large-scale H13 steel technology, the carbides, inclusions, solute segregation and mechanical property of H13 steel were analyzed. The results demonstrated that the implementation of axial static magnetic field (ASMF), the area fraction and size of carbides decreased, and the segregation rate of the elements (C, Mo, V and Cr) decreased. The reason is that the application of ASMF could shorter the local solidification time, decrease the dendrite spacing, alleviate the degree of interdendritic segregation, which limits the time and space for the generation and further growth of carbides. After ASMF was applied, there were lesser and smaller inclusions in H13 steel. Smaller droplet and shallower metal pool are the consequence of utilizing ASMF, which improves the kinetic conditions and removal process that inclusions migration to the slag-metal interfaces. Moreover, samples after forged annealing showed that the average grain size of H13 steel decreased when ASMF was applied, which significantly enhances the mechanical properties. In the absence of ASMF, the product of strength and elongation was 22,599 MPa pct. After applying 60 mT ASMF, the product of strength and elongation increased to 28,770 MPa pct. [ABSTRACT FROM AUTHOR]

The work functions of different stainless steels were investigated and found to be in the range of 4.08–4.19 eV. They characterize the passive layer, an oxide layer on top of the stainless steel bulk material. This layer makes the steels corrosion-resistant, and it also controls the possible electronic and electrochemical applications of such materials. Structured samples were measured that are especially important for applications of these materials, e.g., in solar cells or fuel cells. The effects of composition changes of the stainless steel on the work function are unexpectedly small, which is likely related to a similar number of d electrons responsible for the electronic band structure. [ABSTRACT FROM AUTHOR]

Additive manufacturing techniques employing laser-based metal melting have garnered significant attention within the scientific community. Despite a decade of comprehensive research on the fundamentals of these techniques, there still remain unexplored facets related to heat flux impact on metallic alloys' properties. Particularly, the effects of point-by-point laser operation on melt pool formation in metallic materials still remain unclear. Thus, this study focuses on the implications of laser metal melting, particularly investigating a point-by-point laser mode operation's influence on melt pool formation and its geometry in the phase-transformation-sensitive material H11 hot work tool steel. To examine the melt pool, singular laser tracks with various laser parameters were scanned across H11 sheet metal, which allowed for the elimination of layer-by-layer heat cycles' influence on the melt pool's microstructure. Samples were examined by means of metallography, revealing significant differences in the melt pool's depth, influenced mostly by exposure time rather than volumetric energy density. Heat-affected zone effects were found to have a limited range and thus potentially marginal effects in layer-by-layer manufacturing conditions. At the same time, retained austenite concentrations near fusion lines have been found within melt pools, suggesting potential micro-segregation of the alloying additions. The results present guidelines towards laser melting processes optimization. [ABSTRACT FROM AUTHOR]

Low carbon manufacturing has gathered attention since wide range of the emission sources belong to industrial activities. The present work analysed five turning parameters which are spindle speed, cutting speed, depth of cut, type of tool material and working material to obtain minimum carbon emission together with high surface quality and minimum processing time. Two different cases are investigated depending on the material families. AISI 1040, AISI 4140 and grade St37 carbon steels are examined in the first case whereas AISI 304, AISI 303 and AISI 316 grade stainless steels are studied as working material without changing the other four parameters. The minimum carbon emission by optimisation was found 14.84 and 24.30 kg carbon dioxide (CO2) for stainless steel and carbon steel, respectively. Furthermore, the best candidate was selected as grade St37 among carbon steel working materials and either AISI 303 or AISI 316 stainless steel was proposed according to the optimisation study. [ABSTRACT FROM AUTHOR]

Excellent wear properties can improve the service performance and service life of high‐Cr hot work die steels. Herein, an innovative method is proposed to introduce TiC nanoparticles into the matrix of high‐Cr hot work die steels, and the effects of TiC nanoparticles on the microstructure and wear resistance of high‐Cr hot work die steels are investigated. In isothermal spheroidizing and quenching and tempering heat treatments, the TiC nanoparticles refine the granular pearlite, tempered martensite, and precipitates, which are attributed to the improved nucleation rates by increasing the number of heterogeneous cores. In sliding wear tests, the nanoparticle‐reinforced high‐Cr hot work die steels show higher wear resistance under the temperatures of 20 and 400 °C. The better wear properties of high‐Cr hot work die steels are because the substrates are strengthened and toughened, the dislocations are hindered, the mating areas are partially separated, and external loads are withstood by nanoparticles. This work shows new prospects for the development of high‐Cr hot work die steels with excellent wear performance. [ABSTRACT FROM AUTHOR]

The present study examines the impact of cryogenic treatment (CT) on W360 and E38K hot work tool steels used in forging dies, subjected to conventional heat (HT) and CTs followed by double tempering treatment. Results reveal that CT facilitates the transformation of retained austenite from 4.9% and 2.5% for W360 and E38K steels, respectively, into martensite to an undetectable limit. Also, when compared to HT, CT at −180 °C results in about 3 times higher amount of the carbide precipitation for both steel types. In contrast, a slight increment in the hardness values with decreasing treatment temperature is observed. Notch impact test results indicate higher impact energy with lower CT temperatures, particularly notable in W360 steel. Although both steel types exhibit almost similar impact energy values at room temperature, E38K steel has ≈100% higher energy at 350 °C. DCT‐treated samples show improved wear resistance at lower cryogenic temperatures. Cryotreated W360 steel displays nearly 25% less wear rate than cryotreated E38K steel. The study underscores the suitability of W360 and E38K steels for hot work applications, with CT enhancing their mechanical and microstructural performance, particularly in W360 steel due to its higher carbide density. [ABSTRACT FROM AUTHOR]

Composite steel‐timber beams – initial ideas for structural design Since the introduction of the Green Deal and the EU Taxonomy Regulation, pressure in construction market has increased to design load‐bearing structures in addition with a view to greater sustainability. Composite beams in steel‐timber construction can contribute to this. However, reliable calculation rules for steel‐timber composite beams do not yet exist. Working Group 6 of TC11 in the European Convention for Constructional Steelwork (ECCS) deals with hybrid steel‐timber structures and this article presents initial ideas for calculation approaches for steel‐timber composite beams. The problems are tackled that, in contrast to concrete, the material timber has a significant tensile strength and the different types of shear connectors between steel and timber can also show a variety of load‐slip curves. Finally, a first comparison between the presented calculation method and a large‐scale test is presented. [ABSTRACT FROM AUTHOR]

This article discusses the modern welfare state through an in-depth look at the history of automation in United States labor. Topics include the stealth industrial policy, national security and the Labor-Management Advisory Committee. As well as an emphasis on the impact on automation on the steel industry and its workers.

The alloying elements present in both tool steel and aluminium are influenced in the dissolution of tool steels in molten aluminum alloys. This study aims to predict how the alloying elements in the tool steel, particularly nickel (Ni) and molybdenum (Mo), impact the formation of the interaction layer between the tool steel and the molten aluminium alloy. The interaction layer between the investigated tool steels Dievar or RavnexHD and the aluminium alloys Al99.9 and Al99.7 consists of an intermetallic and a composite layer. The interaction layer between the investigated tool steels and the AlSi12 aluminium alloy consists of three different interaction layers. The hot-work tool steel RavnexHD shows the better solubility resistance in various molten aluminium alloys. The main alloying element in the tool steels investigated that has an influence on the dissolution of tool steel in molten aluminium is Ni, which is present in higher amounts in RavnexHD. Ni incorporate in the matrix, and inhibits the diffusion of iron and aluminium through the matrix. Mo in Dievar tool steel forms carbides, allowing easier diffusion of these elements through the Fe-matrix. The resilience in molten aluminium alloys is demonstrated by Ravnex HD tool steel for hot work. [ABSTRACT FROM AUTHOR]

Carbon steel is widely used, but it is prone to corrosion, which can lead to safety accidents. In this study, a novel Ni‐SiC coating was synthesized on the surface of carbon steel using a one‐step electrodeposition method, and the influence of electrodeposition parameters on the wettability of the coating was investigated. This coating possesses abundant micro‐nanostructures on its surface, which, after being placed in a vacuum drying environment for 2 weeks, endows it with superhydrophobic characteristics. Due to its superhydrophobic properties and the rich micro‐nanostructures, the corrosion current density of this coating is 1/18.95 that of bare steel. After immersion in a corrosive medium for some time, the polarization resistance value of the coated sample was observed to be 13.05 times greater than that of bare steel, demonstrating its remarkable ability to enhance the corrosion resistance of the surface. The results of this study can provide a reference for the anticorrosion work on carbon steel. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the influence of nickel alloy type from the same group, the parameters of flame spraying, as well as the preparation of the substrate and the heat treatments of the substrate on the microstructure of the coating/substrate system. Due to the possibility of applying nickel alloys in corrective maintenance of tools used on elevated working temperatures, hot work tool steel X38CrMoV5-1 was selected as a substrate material. The investigation of the microstructure of the coating/substrate system was carried out according to the factorial design of experiment, where the input factors were varied on two levels. The factors that were varied are: Ni-based self-fluxing alloys - NiCrBSi and NiBSi; distance of the burner from the workpiece - small (6 mm) and large (20 mm); preparation of the substrate - roughened and non-roughened and the heat treatments of the substrate - soft annealed and tempered condition. Ni-based self-fluxing alloys were applied on samples (12,5 × 25 × 25 mm) by flame spraying with simultaneous fusing process. Analysis of the microstructures of the coating/substrate system was carried out on the Leica DM 2500M light microscope. After the conducted analysis the paper concluded that by spraying the selected coatings onto the X38CrMoV5-1 tool steel base, poor quality coatings are obtained, due to the appearance of cracks (NiCrBSi) or separation of the coating from the substrate (NiBSi). This is attributed to the formation of martensitic structure of the substrate after spraying and the presence of residual stresses. [ABSTRACT FROM AUTHOR]

About this conference The International Symposium on Steel Bridges Prague 2024 is organized by the Czech Constructional Steelwork Association (CAOK) in coordination with European Convention for Constructional Steelwork (ECCS) in conjunction with the ECCS Steel Bridge Awards Ceremony and ECCS Annual General Meetings. The International Symposium on Steel Bridges Prague 2024 is going to present and discuss a wide range of topics related to a great variety of research, design and construction activities in the steel bridges sector. This symposium offers an excellent platform to show your new products and the newest technology solutions and equipment to symposium participants by taking part in the exhibition and/or being a significant partner of this international event. Review Process All papers published in this issue were peer‐reviewed by the Scientific Committee of the conference organizer. The review process for this conference was a multi‐stage process. In the first phase a Scientific Committee chose the main conference topic areas. As a result, the Organizing Committee has centrally invited authors to submit abstracts for the corresponding Symposium via the ScholarOneManuscripts Platform. The registration of the abstracts according to the Wiley Publications and Registration Processes also takes place from this platform. The submitted abstracts were reviewed by the Scientific Committee Members and subsequently approved by the corresponding Symposia Chair. Subsequently, the authors were invited to submit their full paper contributions via the Wiley Publications ScholarOneManuscripts Platform. The review process and also the revision process of the full papers were carried out in accordance with the ScholarOneManuscripts. All submitted papers were reviewed in a single‐blind peer review procedure from two members of the scientific committee. The papers had to be accepted by both the reviewers and the chair of the Symposium Steel Bridges. [ABSTRACT FROM AUTHOR]

The focus of this paper was on welding AISI H13 tool steel by the cold metal transfer method to investigate the effects of welding variables on weld bead geometry, microstructure, and mechanical performance. The variable sets consisted of welding voltages of 16–24 V and speeds of 0.25–1.25 mm/s. The weldments were smooth without weld seam defects due to low-voltage welding. The weld bead height was variably influenced by the welding process factors as the welding voltage increased and the welding speed remained constant. The bead height decreased with increasing voltage. Conversely, the dilution percentage increased as the voltage increased. While maintaining a low voltage, a higher bead width was formed. The optimized conditions were achieved at 18 V and 0.25 mm/s, with a bead height of 8.8 ± 0.1 mm, bead width of 17.5 ± 1.0 mm, and penetration depth of 3.59 ± 1.1 mm. However, the influences of the welding speed on microstructural changes were less significant than those of the welding voltage. The voltage had a minimal influence on the ferrite phase formation of the weld metal and heat-affected zones. The mechanical properties, such as the impact toughness of the welded seam, imparted the material with higher absorbed impact energy than the parent material. The impact toughness decreased with an increase in welding voltage. Moreover, the fusion zones of the weldments had lower hardness values than the heat-affected zones and base material. The chromium contents in the microstructure significantly affected the microstructure and microhardness characteristics of the weld metal and heat-affected zones. [ABSTRACT FROM AUTHOR]

The present article addresses the influence of surface mechanical attrition treatment (SMAT) parameters such as a size of the balls (2, 5 and 8 mm ∅ 316L stainless steel (SS) balls) and treatment time (15, 30, 45 and 60 min) on the microstructural features, deformation characteristics, surface roughness and compressive residual stress induced on EN 8 steel. The effective deformation is ~ 25 μm from the top surface along with elongated grains in the near subsurface region. The decrease in crystallite size and an increase in micro-strain become more pronounced during SMAT using balls with a larger diameter and for a longer treatment time. A similar trend is observed in surface roughness. This is mainly attributed to the involvement of higher kinetic energy imposed by SMAT on EN 8 steel. The residual stress induced during SMAT of EN 8 steel measured by x-ray diffraction (XRD) measurements is higher when treated using 2 mm ∅ SS balls when compared to those treated using 5 and 8 mm ∅ SS balls for a similar time duration. Irrespective of the size of the balls, an increase in treatment time has led to a decrease in the residual stress of EN8 steel. Over working of EN8 steel that creates surface cracking has been considered responsible for the decrease in residual stress of EN8 steel treated using 5 and 8 mm ∅ SS balls for any given time duration as well as with an increase in treatment time for a given size of the balls. The development surface cone cracks and material removal from the surface evidenced from the microstructure validates such as an occurrence. When the duration of SMAT is limited to 15 min, a large difference in residual stress values is observed for the EN8 steel treated using 2, 5 and 8 mm ∅ balls, whereas with a further increase in treatment time, the difference between them becomes marginal. Hence, in order to achieve better mechanical properties, the treatment time employed for SMAT of carbon steels should be carefully optimized. The other option available is to choose lower size balls for SMAT. The change in residual stress of EN8 steel as a function of process parameters employed for SMAT and the correlation between the ball size and treatment time with the residual stress are discussed. [ABSTRACT FROM AUTHOR]

Investigating the influence of varying shaft steelwork stiffness on the stability of horizontal mass displacements, which are crucial elements of a conveyance-shaft steelwork system, is a significant step in evaluating the risk of parametric vibrations in steel constructions. While the Rayleigh method is limited to the first approximation in the solution to this analysis, it still provides valuable insights. Our examination indicates that the impact of a varying shaft steelwork system may not be noticeable in practical applications. This is a significant finding, as it suggests that the impact of varying stiffness in real working objects may be ignored, because the increase in the parametric resonance effects is negligible. This underscores the importance of our research in understanding the stability of steel constructions. This research, which involves theoretical analysis, simplifies the dynamic analysis of the conveyance-shaft steelwork system's behavior. The result of the performed analysis is a valuable equation for predicting stable work in real hoist installations. [ABSTRACT FROM AUTHOR]

Clostridioides difficile is a widely distributed anaerobic pathogen. C. difficile infection is a serious problem in healthcare. Its biofilms have been found to exhibit biocorrosivity, albeit very little, but sufficient for it to correlate with biofilm growth/health. This work demonstrated the use of a disposable electrochemical biofilm test kit using two solid-state electrodes (a 304 stainless steel working electrode, and a graphite counter electrode, which also served as the reference electrode) in a 10 mL serum vial. It was found that the C. difficile 630∆erm Adp-4 mutant had a minimum inhibitory concentration (MIC) for vancomycin twice that of the 630∆erm wild type strain in biofilm prevention (2 ppm vs. 1 ppm by mass) on 304 stainless steel. Glutaraldehyde, a commonly used hospital disinfectant, was found ineffective at 2% (w/w) for the prevention of C. difficile 630∆erm wild type biofilm formation, while tetrakis(hydroxymethyl)phosphonium sulfate (THPS) disinfectant was very effective at 100 ppm for both biofilm prevention and biofilm killing. These antimicrobial efficacy data were consistent with sessile cell count and biofilm imaging results. Furthermore, the test kit provided additional transient biocide treatment information. It showed that vancomycin killed C. difficile 630∆erm wild type biofilms in 2 d, while THPS only required minutes. [ABSTRACT FROM AUTHOR]

As an important part of die steels, hot-work die steels are mainly used to manufacture molds made of solid metal or high-temperature liquid metal from heating to recrystallization temperature. In view of the requirements for mechanical properties and service life for hot-work die steel, it is conducive to improve the thermal fatigue resistance, wear resistance, and oxidation resistance of hot work die steel. In this review, the main failure modes of hot-work die steel were analyzed. Four traditional methods of strengthening and toughening die steel were summarized, including optimizing alloying elements, electroslag remelting, increasing the forging ratio, and heat treatment process enhancement. A new nano-strengthening method was introduced that aimed to refine the microstructure of hot-work abrasive steel and improve its service performance by adding nanoparticles into molten steel to achieve uniform dispersion. This review provides an overview to improve the service performance and service life of hot work die steel. [ABSTRACT FROM AUTHOR]

Low fracture toughness is a common problem encountered by many researchers in the application of pure TiB2 coatings. To improve their properties, a convenient and useful method is the use of doping, so this study proposes the deposition of TiB2 enriched with Zr on a steel substrate. The objective of the research was to investigate the impact of Zr addition to TiB2 coatings on both their mechanical and tribological properties. Four coatings with varying compositions (pure TiB2; TiB2 doped with 3, 6, and 10 at.% Zr) were deposited using magnetron sputtering from TiB2 and Zr targets. The coating structures were analyzed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Nanoindentation, scratch test, and ball-on-disk test were used to determine the mechanical and tribological properties. In most cases, only two factors have a significant impact on the mechanical and tribological properties of the Zr-doped coating. Firstly, a change in the preferred orientation of the coating from (102)(111) to (100) results in increased hardness and wear resistance. Secondly, a reduction in crystallite and column size enhances ductility and fracture toughness by impeding or altering the direction of crack propagation. Based on the study, one can conclude that the optimal Ti1-xZrxB2 properties were obtained for 6 at.% Zr content. [ABSTRACT FROM AUTHOR]

In October 2019, the largest fire in a commercial building in New Zealand since 1947 burned for over ten days through the roof and upper floor of the 120 m wide × 100 m long New Zealand International Convention Centre, which was under construction and nearing completion at the time. The steel composite and reinforced concrete framed building features five storeys above grade of structural steel framing with composite floors, comprising heavy, intricate steel work that was impacted by the fire. The main steel structure performed very well in response to fire exposure ranging from low to severe, with minimal damage and distortion to the heavy steel roof members in general, considering the severity of the fire. Secondary steel angles, tubular steel, and wide-flange members at the roof elevation were locally more heavily distorted. A very detailed post-fire evaluation of the structure was carried out, comprising mapping of the fire effects, deflections, metallurgical changes, extensive numerical modelling, and full scale in-situ experimental testing. The outcome resulted in retention of over 95% of the total roof steelwork (2500 tonnes). This paper provides an overview of the fire and the key steps involved in the post-fire structural evaluation of this unique fire case history. [ABSTRACT FROM AUTHOR]

In order to improve the wear resistance of hot‑rolled high speed steel work rolls, Inconel 625 alloy coatings with 0%, 10%, 20%, and 30% (Ti, W) C content were prepared on ductile iron substrate by laser cladding technology. The effect of (Ti, W) C particles on the microstructure, hardness and wear resistance of the coatings was investigated. The (Ti, W) C particles are uniformly distributed in the coating, and have a good combination with the Inconel 625. The hardness of the coating increases from HV0.2280 to HV0. 2424 with the increase of the (Ti, W) C particle content. In the process of friction and wear, the (Ti, W) C particles, as hard phases, inhibit the local plastic deformation of the material during wear. The wear amount of Inconel 625 alloy coating containing 30% (Ti, W) C particles is only 0. 015 m³, and the average friction coefficient is 0. 061 6. It has been proved that the hardness and wear resistance of Inconel 625 alloy coating are significantly improved and the friction coefficient is reduced by adding a reasonable amount of (Ti, W) C particles. [ABSTRACT FROM AUTHOR]

This research aims to present the best conditions for cyclic heat treatment of AISI H13 hot work tool steel to improve its mechanical properties and achieve a microstructure with fine grains. To accomplish this, 27 experiments were designed using the full factorial design approach. The austenitizing, intermediate salt bath and quenching salt bath temperatures were kept constant, while the austenitizing times of 5, 10 and 15 min, holding in the intermediate bath of 5, 10 and 15 min and the number of cycles of 2, 3 and 4 were varied. The best mechanical properties were obtained with 5 min of austenitizing, 15 min of intermediate bath and 4 cycles, resulting in a 41% reduction in grain size and a significant increase in toughness compared to the control sample. EDX analysis revealed that higher austenitizing temperatures led to greater carbon dissolution in austenite, which in turn resulted in the formation of carbides and their penetration into grain boundaries, leading to grain boundary fracture. [ABSTRACT FROM AUTHOR]

This study examines the contribution of confinement with variations in spacing sh = (50, 65, and 80) mm and concrete reinforced with steel fiber to displacement ductility. Eight test column specimens (No. 1, 2, 3, 6, 7, 8, 11, and 12) were also reinforced with stirrups according to ACI 318M:19 provisions while four test column specimens (No. 4, 5, 9, and 10) deliberately reinforced with a slightly wider spacing of stirrups with different yield strengths (fy) (lower than the code requirements). However, the volumetric ratio of the steel fiber was varied, i.e. Vf = 0%, 0.5%, 1%, 1.5%, and 2%. The column was then subjected to a quasi-cyclic and a constant axial load of Pa = 0.121.Ag.fc'. The test results indicated that all test column specimens could attain the full ductile/fully ductile criteria since μ>4. When the drift ratio required by ACI 318M-19 is observed, the use of combined confining stirrups and steel fiber works together simultaneously to achieve a drift ratio capacity that exceeds the minimum required target of 3%, meaning that the columns could perform satisfactorily. [ABSTRACT FROM AUTHOR]

Partially encased concrete (PEC) has better mechanical properties as a structure where steel and concrete work together. Due to the increasing amount of construction waste, recycled aggregate concrete (RAC) is being considered by more people. However, although RAC has more points, the performance is inferior to natural aggregate concrete (NAC). To narrow or address this gap, lightweight, high-strength and corrosion-resistant CFRP can be used, also protecting the steel flange of the PEC structure. Therefore, carbon fiber reinforced polymer (CFRP) confined partially encased recycled coarse aggregate concrete columns were studied in this paper. With respect to different slenderness ratios, recycled coarse aggregate(RCA) replacement ratios, and number of CFRP layers, the performance of the proposed CFRP restrained columns are reported. The RCA replacement ratio is analyzed to be limited negative impact on the bearing capacity, generally within 6%. As for the slenderness ratio, the bearing capacity increased with it. However, wrapping CFRP significantly increased the bearing capacity. Considering the arch factor, a simple formula for calculating the ultimate strength of CFRP-confined partially encased RAC columns is developed based on EC4 and GB50017-2017. By comparison with the experimental values, the error is within 10%. [ABSTRACT FROM AUTHOR]

Mechanical properties including yield strength, hardness, and strain hardening are superior in additively manufactured H13 hot work tool steel (AMH) compared to conventional H13 (CMH), which are correlated with microstructural characteristics. Comprehensive microstructural analysis reveals that the strain is highly localized in the cell structure with retained austenite in AMH. Quenching and tempering (QT) heat treatment removes the cell structure and retains austenite from AMH, resulting in a microstructure and mechanical properties similar to CMH after QT. The constitutive equation for yield strength shows that retained austenite with sufficient amount of dislocation density in martensite contributes to higher yield strength in AMH than CMH and identical strengthening mechanism between AMH and CMH after QT. Furthermore, microstructural changes during plastic deformation are investigated to find the origin of high strain‐hardening rate in AMH. The relationship between hardness and indentation depth yields the higher statistically stored dislocation density in AMH than CMH. In addition to higher dislocation accumulation, transformation of retained austenite to α′ martensite results in transformation‐induced plasticity effect, which contributes to strain hardening. [ABSTRACT FROM AUTHOR]

The effects of quenching and tempering temperatures on the microstructure and mechanccal properties of H13 hot work die steel were rnvestigated by using metallograplic microscopy, scanning electron microscopy, microhardness tesiing,and tensle testing. The findings revealed that secondary tempering treatment and appropriate reduction in tempering temperature result in the effective precipitation of iiner and more dispersed carbides and the complete release of quenching stress. As a resutt, the hardness and toughness of H13 hot work de steel were significantly improved. Notably,when the quenching temperature was 1 000 C and the tempering temperature was 520 C, the mechanical properties are superior, characterized by smaler tempering martenstte size and more uniform structural dsstribution. Under these cond!tions, the hardness measureed 487 HV, the tenslle strength reached 1 779 MPa,and the elongation was 11. 5%. The analysis of the tenslle fracture morphology reveals the presence of numerous dimples in the specimen after the tempering process, indccative of typca! ducile fracture charac t eris i ccs. Fur t hermore,a model was developed to describe t he soft ening behavior of H13 s t eel during t empering n t he t empera t ure range of 520 C to 600 C. [ABSTRACT FROM AUTHOR]

The sliding layer created during operation of the expanded graphite–steel combination has had a huge impact on the effectiveness of the friction process, and thus on the sustainable development of society. Knowledge of the factors determining the properties of the sliding layer will make it possible to reduce friction resistance in the future through the proper design and selection of sliding pairs for given applications. This paper studies the effect of the moisture content of expanded graphite on the formation of a sliding layer on a stainless steel surface. The tests were carried out in static contact for 30 s and dynamic contact for 15 and 30 min, for loads of 10, 20, and 30 N and speeds of 25 and 50 mm/s. To determine the changes in surface geometry due to material transfer, the Ra roughness value of the surface of stainless steel samples was measured. In order to realize the purpose of the work and evaluate the effect of moist rings on the resulting sliding layer, the results of the surface roughness of stainless steel samples working with dry and moist graphite rings were compiled. The obtained results show that the presence of water in the stainless steel-expanded graphite friction node affects the formation of a sliding layer. The resulting layer reduces the surface roughness of the cooperating materials and prevents their accelerated wear. After 5 min of work with the water-soaked graphite counter-sample, depending on the applied friction conditions, a reduction in the surface roughness of the stainless steel sample was achieved in the range of 11–18% compared to the initial value. After 30 min of operation, the surface roughness decreased by 3 to 25%. Pilot studies have shown that operating conditions influence the formation of a sliding layer in the stainless steel-expanded graphite tribological contact. This confirms the validity of conducting further research in this area. [ABSTRACT FROM AUTHOR]

For weight reduction, multi-material designs comprising metal and fiber-reinforced plastic (FRP) components in vehicle body structures have been increasingly used. However, the commonly used resistance spot welding (RSW) technology for car body assembly cannot be employed to join sheet metal and FRPs, limiting the use of FRPs. To solve this problem, a novel resistance insert spot welding (RISW) technique was developed in this work for RSW of steel parts and FRP structure parts made by injection molding. Small inserts were developed by using finite element method and experiments that may be welded to different micro-alloyed and dual-phase sheet steels using the projection welding method. The usual flange width of original equipment manufacturers could be kept unchanged. Using the developed insert and welding parameters, the maximum temperature in the FRPs surrounding the inserts was limited to 255 °C, minimizing the damage to polyamide 6 (PA6) material (with 40 wt% glass fiber). A weldability range between 2.5 and 7 kA could be achieved. The joining strength of RISW between a micro-alloyed HC340 steel in 0.75 mm and 1.5 mm thickness and a 2.5 mm/3.0 mm PA6-GF40 material is 20 to 80% higher than self-piercing riveting (SPR). For high-speed loading, RISW strength increases by 39 to 56% further. Finally, RISW was successfully applied to an FRP–steel roof-frame sub-assembly that consists of 19 simultaneously integrated inserts, achieving 10% weight reduction. [ABSTRACT FROM AUTHOR]