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To investigate the effect of reoxidation on inclusions characteristic during casting in Al‐killed steel containing rare earth, two industrial heats, including one of steady casting and the other of reoxidation, are performed with sampling from Rheinstahl Heratus, tundish, submerged entry nozzle, and slab. In the present study, air absorption occurs at the submerged entry nozzle and caused the reoxidation of molten steel. As a result, the number of inclusions increases significantly, and nearly spherical Ce2O2S inclusions are transformed to clustered‐like CeAlO3, which increases the average size of inclusions from 3.92 to 9.21 μm, thereby resulting in serious nozzle clogging and slab defects. The results of thermodynamic calculation show that Ce2O2S is transformed to CeAlO3 with total oxygen content increases under different Ce additions, and this transformation of inclusions can be inhibited by controlling the value of [Ce]/[O] above 2.12. Based on the experimental results and the theoretical analysis, the evolution mechanism of inclusions during reoxidation is clarified. This study can provide theoretical guidance to alleviate the harm of reoxidation to Al‐killed RE‐steel from the inclusion‐controlling perspective. [ABSTRACT FROM AUTHOR]

The residence time distribution (RTD) curve is a simple and useful method to analyze the flow behavior in the tundish. In the last decades, analysis result acquirement based on the RTD curve has been applied to design and optimize the flow control devices in a simple bare tundish or a multistrand tundish. There are many factors to affect the acquirement and analysis of the RTD curve, such as the tracer, the measuring technology, and the analysis model. In order to find a solution for the above issues, the latest progress and research status of RTD curve are discussed in the fields of water model, mathematical model, RTD analysis model, and measuring technology. After comparison, the KCl solution is a good tracer, and its tracer concentration and volume can be determined by the dimensionless tracer parameter (Dtp). The extended combined model can be applied to analyze the RTD curve by pulse input of tracer, and the mean residence time is the key parameter to identify the difference in fluid characteristics among the strands. [ABSTRACT FROM AUTHOR]

Since the invention of Hadfield steel in 1882, it has seen significant interest and development of several grades and studies to improve its beneficial characteristics due to its widespread use in heavy industry. The present work concerns the development of a new grade of Hadfield steel belonging to the standard ASTM-A128 grade B-2, by reducing the formation of carbides during the casting of Hadfield steel with the use heat treatments. Besides, a new technique was adopted without recourse to heat treatments to decrease the presence of carbides during steelmaking. The microstructure analysis is carried out with optical and scanning electron microscopes and X-ray diffraction. Mechanical properties were determined by the uniaxial tensile test, Charpy impact test and microhardness Vickers. Furthermore, tribology tests were applied to study the wear resistance of the developed steel. Finally, an electrochemical test was realized to characterize the corrosion resistance. The results show that the samples treated at 1050 °C for 2 h 30 min exhibit high ductility and tensile strength as well as good impact resistance. This treatment also improved the wear and corrosion resistance of the cast steel due to the dissolution of the carbides. [ABSTRACT FROM AUTHOR]

In this work, the effect of Ti addition and the cast part size on the solidification structure and mechanical properties of a medium carbon, low alloy cast steel was analyzed. The experimental analysis involved the design of the melts by using Thermo-Calc® software, where different amounts of Ti added to a standard chemical composition of an AISI 13XX steel were simulated. Then, the solidification macrostructure (dendritic pattern and grain size) and microstructure were characterized by using conventional and specific metallographic techniques. Finally, the mechanical behavior in terms of hardness and tensile properties were evaluated. The results show that the addition of 0.12% of Ti promotes a fine dispersion of Ti nitrides and carbides, but when the Ti concentration raises to 0.2%, the size of the Ti nitrides and carbides increases while its amount decreases. Ti nitrides and carbides particles act as nucleation sites for the precipitation of ferrite from austenite, and it was found that the addition of Ti in the higher concentrations refines the solidification macrostructure (dendritic pattern) for both cast part sizes evaluated. Regarding mechanical properties, the addition of Ti does not significantly vary the ultimate tensile strength but reduces the total elongation for cast part sizes. [ABSTRACT FROM AUTHOR]

Gears in a strip mining dragline failed in service. The material was identified as a low-alloy (NiCrMoV) steel. SEM analysis indicated that the initial fracture and subsequent fractures resulted from impact or a suddenly applied load. Mechanical testing indicated that the gears had low impact strength. Failure was attributed to low toughness caused by the absence of, or improper, heat treatment. Casting defects identified during metallographic examination were determined to be the fracture initiation site, but were considered less significant than the low as-received impact strength of the material. It was recommended that the equipment manufacturer implement an appropriate heat treatment to meet the impact requirements of the application. [ABSTRACT FROM AUTHOR]

A series of experiments and thermodynamic analyses were carried out to find a countermeasure to prevent submerged entry nozzle clogging during continuous casting of Ti-added Ultra-Low C (Ti-ULC) steel, by suppressing CO gas generation in the nozzle refractory. SiO 2 and C in usual nozzle refractories proceeded a carbothermic reaction, which generated the CO gas. The CO gas then reoxidized Ti-ULC steel, and a mixture of alumina and Fe t O–Al 2 O 3 –TiO x liquid oxide formed, which was reported to be an initial clog deposit. A concept of "CO absorber" was proposed to absorb the generated CO gas back into the refractory, thereby suppressing the reoxidation. This decreased the thickness of the reoxidation reaction product layer at the interface between the refractory and the steel, which could play as the initial clog deposit. Al 4 C 3 , B 4 C, CaC 2 , and Al were considered as the candidates for CO absorbers. It was found that B 4 C was the best candidate thanks to its anti-hydration character, high-temperature stability, and the extent of absorbing CO gas. A series of hot tests were carried out by reacting synthesized refractories in which a certain amount of the candidates were blended. The refractory with 3 mass pct. B 4 C showed the best result. [ABSTRACT FROM AUTHOR]

Also, the number of CCMTs I N i is obtained using the measured variance based on HT ht . After that, the volume of each CCMT is computed using HT ht . In order to address this issue, [8] in 1986 improved the determination of I V i SB p sb in Traditional Model I as HT ht Graph (2) In the following text, the model with Eq. (2) is referred to as ' I Traditional Model II i '. [Extracted from the article]

A large-eddy simulation (LES) based meshless model is developed for the three-dimensional (3D) problem of continuous casting (CC) of steel billet. The local collocation meshless method based on radial basis functions (RBF) is applied in 3D. The method applies scaled multiquadric (MQ) RBF with a shape parameter on seven nodded local sub-domains. The incompressible turbulent fluid flow is described using mass, energy, and momentum conservation equations and the LES turbulence model. The solidification system is solved with the mixture continuum model. The Boussinesq approximation for buoyancy and the Darcy approximation for porous media are used. Chorin's fractional step method is used to couple velocity and pressure. The microscopic model is closed with the lever rule model. The LES model is compared to the two-equation Low Re k − ε turbulence Reynolds Averaged Navier–Stokes (RANS) model in terms of temperature, velocity and computational times. The LES model resolves transient character of vortices which RANS-type turbulence models are unable to tackle. The computational cost of LES models is considerably higher than in RANS. On the other hand, it results in a much lower computational cost than the direct numerical simulation (DNS). The paper demonstrates the ability of the method to solve realistic industrial 3D examples. Trivial adjustment of nodal densities, high accuracy, and low numerical diffusivity are the main advantages of this meshless method. [ABSTRACT FROM AUTHOR]

Reduction of area (RA) measurement in a hot ductility test is widely used to define the susceptibility of surface crack of cast steel, but the test is complex because it entails processes such as specimen fabrication, heat treatment, tensile testing, and analysis. As an alternative, this study proposes a model that can predict RA. The model exploits the relationship between precipitation and RA behavior, which has a major effect on hot ductility degradation in high-Mn steels. Hot ductility tests were performed using four grades of high-Mn steels that had different V-Mo compositions, and the RA behavior was compared with the precipitation behavior obtained from a time-temperature-precipitation (TTP) graph. The ductility deterioration of high-Mn steels shows a tendency to start at the nose temperature TN at which precipitation is most severe. Using this relationship, we developed a model to predict the hot ductility degradation temperature of high-Mn steels. TN was calculated using J-matpro software (version 12) for 1500 compositions of high-Mn steels containing the precipitating elements V, Mo, Nb, and Ti, and by applying this to a deep neural network (DNN), then using the result to develop a model that can predict TN for various compositions of high-Mn steel. The model was tested by comparing its predicted RA degradation temperature with RAs extracted from reference data for five high-Mn steels. In all five steels, the temperature at which the RA decreases coincided with the value predicted by the DNN model. Use of this model can eliminate the cost and time required for hot ductility testing to measure RA. [ABSTRACT FROM AUTHOR]

This article deals with the simple preparation of environmentally friendly acrylic latex binders, which are functionalized with nanoparticles of metal oxides, namely MgO, ZnO, La2O3 and combinations of MgO and ZnO, serving as functional components to achieve antimicrobial properties, but also to improve physical–mechanical properties and chemical resilience. The incorporation of uncoated powder nanoparticles was performed during the synthesis, using the two-stage semi-continuous emulsion radical polymerization technique, to obtain latexes containing 0.5%–1.3% nanoparticles relative to the polymer content. Changes in latex performance due to nanoparticles were compared from the point of view of the type and concentration of metal oxide nanoparticles in latex. The results of the tests showed that all types of nanoparticles showed very promising properties, while with increasing concentration of nanoparticles there was an improvement in properties. The nanoparticles in latex provided interfacially crosslinked transparent smooth coating films with high gloss and good physical–mechanical properties. Latexes containing the highest concentration of nanoparticles provided coatings with significant antimicrobial activity against all tested bacterial and fungal strains, but also in-can preservative stability of liquid latex. Furthermore, the coatings were resistant to solvents, and in addition, latexes with MgO nanoparticles showed a significant decrease in the minimum film-forming temperature, and latex with a concentration of about 1.3% MgO did not show any flash corrosion under the coating film cast on a steel substrate. The latexes containing MgO and La2O3 nanoparticles provided coatings that were very resistant to water bleaching. [ABSTRACT FROM AUTHOR]

This study seeks to investigate the local reinforcement of low carbon cast steel specimens with WC–metal matrix composites (WC–MMCs), to obtain a new material effective in competing with hard alloy steels. For this purpose, a powder compact of tungsten carbide (WC) and iron (Fe) was prepared and placed in the mold cavity before casting. The reactions that occurred with the molten steel led to the formation of the WC–MMC and, consequently, to the local reinforcement of the steel. The microstructure of the WC–MMC reinforcement was characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). The results showed a microstructural variation throughout the depth of the reinforcement. In the surface region, most of the original WC particles retain their polygonal morphology, but towards the base metal, the dissolution of the WC particles increased with the formation of (Fe,W)6C carbides. Closer to the base metal, dendritic eutectic carbides of (Fe,W)6C and fine (Fe,W)23C6 precipitates in a matrix of martensite were formed. The mechanical properties of the reinforcement were evaluated by hardness and ball-cratering abrasion tests. The results revealed a significant increase in hardness, being three times harder than the base metal, and a decrease of 39% in the wear rate. [ABSTRACT FROM AUTHOR]

The great mechanical performance of 18Ni300 maraging steel, achieved during ageing treatment by the precipitation of fine intermetallic precipitates within a martensitic matrix, makes this material a good choice for demanding applications such as injection moulds for the automotive industry. Its ease of manufacture by selective laser melting (SLM) allows parts with a higher degree of complexity and the possibility of customised design. Nevertheless, a comprehensive analysis of the performance of the manufactured parts is important to understand the differences between components manufactured by SLM and those produced by conventional methods. In this work, the mechanical performance of a maraging steel 18Ni300 manufactured by SLM was compared with that of a commercial cast steel 18Ni300, as well as their tribological performance during dry sliding against a polypropylene matrix composite reinforced with 40 wt% E-glass fibres (PP40), a material commonly used in automobile parts and known for its abrasiveness. The results show that the steel manufactured by SLM and aged at 510 ºC for six hours has higher hardness and better mechanical properties than the cast steel. Dry sliding wear tests of the aged steels against PP40 showed a 33% lower specific wear rate for the steel manufactured by SLM compared to the cast steel. These results can be explained by the refined microstructure resulting from the rapid cooling during the SLM process. Different wear mechanisms were found: abrasion was the predominant mechanism for the steel manufactured by the SLM process, while abrasion and adhesion were observed for the cast steel. [ABSTRACT FROM AUTHOR]

Herein, a new Euler–Euler–Lagrange hybrid method is used to simulate the liquid–solid–gas three‐phase flow in a continuous casting mold. In the used method, bubble coalescence and breakup, inclusion aggregation, bubble–inclusion interaction, and complex force balance of bubbles near the solidification front are simultaneously considered. The predicted inclusion size distribution is in good agreement with previous industrial test results. With the application of this method, inclusions can be tracked even if they are collected by bubbles. This characteristic is useful in the study of harmful phenomena in that bubbles are captured by the solidification front after collecting numerous inclusions. Herein, the effects of various simulation factors on results are studied. The descending order of importance of the simulation factors is as follows: bubble–inclusion interaction, bubble coalescence and breakup, and inclusion aggregation. Ignoring any of these factors underestimates the inclusion removal rate and increases the prediction deviation of the inclusion size distribution. Although inclusion aggregation has little effect on the overall removal fraction, it is the most important way to remove small inclusions with a maximum size of 14.14 μm under the conditions of this research. [ABSTRACT FROM AUTHOR]

This work presents the novel high‐strength cast steels Fe81Cr15Mo1V2C1 and Fe80Cr15Mo1V3C1 (wt%) with high resistance against abrasion and acid corrosion. By means of a tailored alloy design and a special casting technique, implying high solidification rates, multiphase microstructures composed of martensite, austenite and a complex arranged carbidic network are formed. The increase of the vanadium concentration by 1 wt% results in an enhanced content of martensite and a decreased fraction of metastable retained austenite as detected by X‐ray diffraction and magnetization studies. This affects significantly the deformation, strengthening and wear behavior of the presented cast steels. Nevertheless, both steels achieve very high compressive (>4500 MPa) and tensile strengths (>1100 MPa) already in the as‐cast state. Furthermore, a distinctly higher abrasive wear resistance than the conventional X90CrMoV18 cold‐work steel was determined for the novel alloys. In conclusion, the results of the microstructural, mechanical, tribological and corrosive characterizations illustrate the impact of alloy design and special solidification conditions on the microstructure and resulting properties for the newly developed cast steels. In addition, the high potential of Fe81Cr15Mo1V2C1 and Fe80Cr15Mo1V3C1 as materials for high‐performance tools, requiring high strength besides high resistance against abrasive wear and acid corrosion, is demonstrated. [ABSTRACT FROM AUTHOR]

This paper presents a 0.25 scale quasi-three-dimensional hydraulic model experiment of transient fluid flow phenomena during continuous casting of steel. The relationship between the continuous casting process and the hydraulic jump phenomenon is established. The casting process in the mold is divided into four stages (I–IV) from the beginning to the end of continuous casting. The filling process involves stages I–II and is investigated by high-speed camera. The filling process is part of the cast start. In this paper, the hydraulic jump behavior varies and is controlled by different spring and iron chips arrangement on the dummy bar during the filling process. A filling coefficient is proposed to judge the best filling conditions and apply them to the whole filling process. There is an optimal spring and iron chip arrangement, which can adjust the hydraulic jump to optimize the initial flow field during the filling process, even the whole continuous casting process. [ABSTRACT FROM AUTHOR]

Hot-core heavy reduction rolling (HHR2) is an innovative technology that uses a temperature gradient to improve the core quality of continuously cast steel at the end of solidification. In the current study, the influence of the temperature on the quality of continuously cast steel rolled with HHR2 is investigated through experiments and simulation. Four HHR2 processes with different surface deformation temperatures (800, 850, 950, and 1100 °C) are carried out. The results show that the surface deformation temperature of 1100 °C led to the best density quality of the steel compared with several other processes. Moreover, based on the cross-section temperature field and the influence of temperature on deformation resistance, an effective strain evaluation method of the billet center is proposed to analyze HHR2 billet deformed quality. Furthermore, the HHR2 processes and traditional hot rolling process are compared. The results show that the 1100 °C HHR2 process has a higher temperature gradient than traditional hot rolling with the same surface temperature, which enhances both the stress triaxiality ratio and effective strain to obtain a higher core quality billet. [ABSTRACT FROM AUTHOR]

In this work, the effect of Ti addition and the cast part size on the solidification structure and mechanical properties of a medium carbon, low alloy cast steel was analyzed. The experimental analysis involved the design of the melts by using Thermo-Calc® software, where different amounts of Ti added to a standard chemical composition of an AISI 13XX steel were simulated. Then, the solidification macrostructure (dendritic pattern and grain size) and microstructure were characterized by using conventional and specific metallographic techniques. Finally, the mechanical behavior in terms of hardness and tensile properties were evaluated. The results show that the addition of 0.12% of Ti promotes a fine dispersion of Ti nitrides and carbides, but when the Ti concentration raises to 0.2%, the size of the Ti nitrides and carbides increases while its amount decreases. Ti nitrides and carbides particles act as nucleation sites for the precipitation of ferrite from austenite, and it was found that the addition of Ti in the higher concentrations refines the solidification macrostructure (dendritic pattern) for both cast part sizes evaluated. Regarding mechanical properties, the addition of Ti does not significantly vary the ultimate tensile strength but reduces the total elongation for cast part sizes

In view of the characteristics of drastic changes in shell thickness and temperature field of continuous casing billets in each sector, the variation law of limit reduction of billets n different reduction intervals was studied systematically. Taking A36 steel continuous casting billets as the research object, a three-dimensional thermodynamic coupling model including billet, casting roller and the multi-body contact between them was estabished. Under the premise of ensuing the processing quality, the limit reduction reduction zones and reduction distributions of the casing billets were studied systematically. The results show that the limit reduction of A36 steel billets from the first section of bending section to the tenth section of horizontal section is as 3.87 ~ 6.96 mm. The suitable reduction sections at the end of solidficaron are the 8th ~ 10th sections and it is suitable to distribute the reduction evenly in these reduction sections. [ABSTRACT FROM AUTHOR]

We have investigated the anomalous Ettingshausen effect (AEE) in iron–carbon alloys, i.e., cast irons and steel, using the lock-in thermography. All the alloys exhibit the clear AEE-induced temperature modulation, and their anomalous Ettingshausen coefficient is an order of magnitude greater than that of the pure iron at room temperature. The dimensionless figure of merit for AEE in the ductile cast iron is 55 times greater than that in the pure iron owing to the significant increase in the anomalous Ettingshausen coefficient. Our result reveals a potential of iron–carbon alloys as transverse thermoelectric materials, although the composition and microstructures optimizations are necessary. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The impacts of gating design and riser system on structure-property relationship of high manganese steel specimens produced by CO2 sand molding process were systematically examined. The designing of gating and riser system was done first using the traditional manual method and then by SolidCast simulation method. Confirmatory experiments were done to validate the obtained results. Castings were produced using both designs to verify the extent of defects. Their microstructural and mechanical properties were explored. Visual examination of castings designed by manual method showed major shrinkage defects, whereas software designed castings were quite sound showing no shrinkage (macro porosity) and micro porosity. Furthermore, optical microscopy and SEM analysis were performed to study microstructure of the specimens. It was found that the defect-free, software-designed castings with optimized parameters showed ∼25 % improvement in yield strength, ∼20 % in tensile strength and ∼30 % in hardness. [ABSTRACT FROM AUTHOR]

The mass‐loss, polarization tests, and electrochemical impedance spectroscopic strategies were applied to assess the inhibition performance of the environmentally friendly inhibitor Araucaria heterophylla leaves extract (AHLE) for soft‐cast steel corrosion safety in 1 M HCl at 300 ± 1 K. The environmentally friendly inhibitor creates a protective coat on soft‐cast steel that decelerates the corrosion process in acidic environments. The percentage inhibition effectiveness, corrosion current density, corrosion potential, cathodic and anodic Tafel slopes are being assessed. The outcomes of chemical and electrochemical research are almost similar. The inhibitor's inhibition activity was well illustrated by the AHLE adsorption on soft‐cast steel follows the Langmuir adsorption isotherm. According to the study, AHLE is a mixed kind of inhibitor. Experiments were conducted with varying inhibitor amounts and temperatures. The calculated ΔGadso$\Delta G_{{\rm{ads}}}^o$ values were in the range of −33.75 to −34.40 kJ/mol, which discloses the corrosion inhibitory action is exothermic and spontaneous. Scanning electron microscopy, Fourier transform infrared spectroscopy, and contact angle techniques were used to determine the association of the AHLE on the metal surface. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Continuous casting is the most important route for the production of steel today. Due to the physical, mechanical, and chemical components involved in the production, continuous casting is a very complex process, pushing conventional methods of monitoring and control to their limits. In recent years, this complexity and the increasing global competition created a demand for new methods to monitor and control the continuous casting process. Due to the success and associated rise of machine learning techniques in recent years, machine learning nowadays plays an essential role in monitoring and controlling complex processes. This publication presents a scientific survey of machine learning techniques for the analysis of the continuous casting process. We provide an introduction to both the involved fields: an overview of machine learning, and an overview of the continuous casting process. Therefore, we first analyze the existing work concerning machine learning in continuous casting of steel and then synthesize the common concepts into categories, supporting the identification of common use cases and approaches. This analysis is concluded with the elaboration of challenges, potential solutions, and a future outlook of further research directions. [ABSTRACT FROM AUTHOR]

Gas injection is a common practice in numerous metallurgical vessels, and continuous casting mold is one of the examples of such vessels. Argon gas injection into the submerged entry nozzle contributes to increasing the sequence length. However, in some unfavorable conditions, these bubbles become responsible for the occurrence of steel defects such as blister, sliver, and mold slag exposure, etc. Bubbles size distribution in the mold is one of the indicators of cast steel slab quality. Previous studies on estimating the bubble size distribution in mold lack in providing the challenges of automatic image processing (IP) techniques employed to measure the size of the bubbles. On the other hand, bubble size measurement studies performed on other reactors such as bubble columns, etc., are programming intensive and need in-depth knowledge of coding. Some automatic IP techniques also exist which facilitate a user-friendly environment and quick estimation of bubble characteristics. Even though these IP techniques are easy to use, an assessment of their applicability with respect to experiments performed in a particular study is required. Therefore, in this study, details of imaging and automatic IP techniques are discussed through a comprehensive comparative analysis. Three different IP techniques were examined for measuring the bubble sizes, and the performances of these techniques were compared with respect to a newly developed manual benchmark technique. One of the identified techniques, Ellipse Split, was applied to estimate the bubble size distribution at different gas fractions for validation. [ABSTRACT FROM AUTHOR]

In the present research, the microstructure and mechanical properties of low-density Fe-0.72Mn-3.7Al-0.53C steel were investigated after solution treatment at 900 °C, 1000 °C, 1110 °C and 1200 °C for 1 h. The density of steel is about 7.0 g·cm−3 due to the addition of a higher content of aluminum elements. The microstructure was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the mechanical behavior was analyzed by room temperature tensile testing. The results show that the microstructure of the steel is ferrite and martensite after solution treatment, and that martensite can be divided into dislocation martensite and twinned martensite according to different substructures. Part of the martensite grows in a mirror-symmetrical manner in order to adjust the strain energy that increases with the system undercooling to form twinned martensite. After solution treatment at different temperatures, the tensile strength and elongation of the steel increased and then decreased with the increase of the solution treatment temperature, and the tensile strength could reach 928.92 MPa, while maintaining excellent toughness and elongation at 5.89%. [ABSTRACT FROM AUTHOR]

Boron-containing steels have good hardenability in wide applications, but may exhibit defects such as transverse corner cracks in slabs after continuous casting. These problems can arise during the post-casting cooling process because boron addition changes the phase transformation behavior of steel. A 3D thermomechanical finite volume model with coupled heat transfer, stress, and phase transformation calculations was developed in the OpenFOAM platform to investigate the temperature history, phase evolution, and stress development during cooling. The model was used to simulate the air cooling process in slabs of two similar steel grades, one with and the other without boron. The simulation results show the slab with boron consists of mostly bainite, in contrast to the non-boron grade which is mostly ferrite and pearlite after cooling. Higher tensile stresses, both peak and residual, and plastic strains, which could lead to cracking, are observed at the edge of slab in the boron-containing grade. The effect of slowing the cooling rate by using a radiation shield was also studied for the boron-containing steel. The reduced thermal gradient and the increased ferrite formation reduced the stresses in the slab. [ABSTRACT FROM AUTHOR]

In this work, we developed a 9 wt% Cr martensitic heat-resistant cast steel with high N and W contents that achieved an excellent high-temperature strength and ductility balance at 923 K, i.e. the ultimate tensile strength and elongation for the steel are ~ 409 MPa and ~ 30.2%, respectively. Meanwhile, it exhibited the encouraging short-term creep performance at 923 K, like, 2425 h for 140 MPa, and 986 h for 155 MPa. Furthermore, the contribution of a mixture matrix including 10.3 vol% δ-Fe and lath martensite remaining to the excellent combination of properties was clarified as related to the W-rich precipitates, which is consisting of 1.7 wt% Laves phase (Fe2W), 0.9 wt% μ phase (Fe7W6). In detail, for the martensite, due to the energy-consuming transformation from μ to Laves, the coarsening rate of martensitic lath decreases as the decreasing ripening rate of Laves, realizing the strengthening. While, the δ-Fe strengthened by a high concentration of fine Laves with needle and rectangle morphologies deformed synergistically with lath martensite, improving the high temperature performance of the steel. The results from the study will provide new insights into the development of high performance martensitic heat-resistant steels. [ABSTRACT FROM AUTHOR]

The paper draws attention to the existing problem of the formation of a defect in the form of a carbide network in cast high-speed steels, which makes products made of such material susceptible to brittle fracture during their operation. The paper also points out high hardness of the particles of pulverized high-speed steel powders, which is why compact products made of these powders are currently obtained by a technologically complex method of hot isostatic pressing. As an alternative to such a powder, a powder mixture of R6M5K5 grade steel is considered, which contains a diffusion-alloyed spongy powder based on tungsten, molybdenum, cobalt, and iron, and can be compacted by cold pressing. A study of the structure of a billet made of such mixture and sintered at 1,000°C revealed the formation of fine-sized carbides, which takes place inside the iron matrix both between and within the grains. Such carbides have a needle-like and flaky shape. Their presence has a positive effect on the hardness of the products. The structure of a billet made of a smaller-fraction powder and sintered at 1,200°C was denser and had finer grains; however, carbides were larger in size and were located as separate inclusions in the structure. It is noted that by selecting the optimal particle size distribution of the powder mixture, compaction pressure, temperature, and soaking time during sintering and subsequent heat treatment, it becomes possible to obtain high-density blanks with fine-grained homogeneous structure. [ABSTRACT FROM AUTHOR]

The results of abrasion-resistance tests that were carried out on cast steel containing 1,1 % C, 16 % Cr, and 0,89 % Mo after several variants of heat treatment (including freeze hardening at -70 °C immediately before tempering at 200° and 550 °C) are presented in this paper. The wear-resistance tests were carried out with the ball-on-disc dryfriction method. In the samples that were tempered at 200 °C (with and without freezing), lower mass losses were obtained than in the samples that were tempered at 550 °C. Additionally, it was found that the applied freezing procedure significantly contributed to the reduction of mass losses in those samples that were tempered at both temperatures. [ABSTRACT FROM AUTHOR]

The results presented in this paper are the next planned stage of research on the process of steel refining from dispersoid non-metallic phase by means of its filtration. Currently, the research has been focused on the process of casting steel using the traditional uphill method. This paper analyzes the prepared and conducted experiments on a semi-industrial scale with the use of multi-hole ceramic filters. The acquired results of macro and microstructure anlyzes, as well as steel cleanliness before and after the filtration process, reflect the course of the research and attest that it can be an effective and cheap method of refining it from non-metallic inclusions. [ABSTRACT FROM AUTHOR]

Nonmetallic inclusions are well known to influence product quality and process stability in the production of steel. A process step that is very sensitive to the presence of nonmetallic inclusion (NMI) is continuous casting. Here, the so‐called clogging phenomenon can occur, resulting in a distinct disruption of the casting process and decreased steel quality. The presence of nonmetallic inclusions considerably contributes to the build‐up of deposits in the submerged entry nozzle provoking instabilities in the flow control system. Numerous research studies have been subject to different clogging mechanisms and related influencing parameters. Interfacial properties significantly influence the behavior of inclusions in the steel–refractory system. The present review demonstrates state of the art concerning the role of NMIs in the appearance of clogging. Particular focus is put on the wetting behavior between the different phases and their consequence for the deposition process. Industrial observations and laboratory methods are summarized and discussed; potential countermeasures are evaluated. A steel group that is especially prone to clogging are Ti‐ ultra low carbon (ULC) steels. An overview of the current understanding of their high clogging tendency and possible influences is presented, considering thermodynamic and interfacial aspects. [ABSTRACT FROM AUTHOR]

Heavy reduction (HR) is an effective process that can significantly minimize the internal porosity and other internal defects in continuous casting steel. Herein, samples taken from different wide‐thick slab positions are examined by scanning acoustic microscopy and 3D reconstructed. The morphology and distribution of microporosities <1 mm in size in the wide‐thick slab are revealed. The microporosities are mainly distributed in a stripping zone symmetric about the centerline within a 1/3‐slab thickness, and most have a considerably obvious long‐ and short‐axis tendency, which can be approximated as ellipsoids. The microporosity evolution in the wide‐thick slab during HR at the solidification end is numerically investigated with a 3D thermal–mechanical coupled model. The microporosity evolution in an aggregated distribution region during HR is little influenced by the surrounding microporosities. With increasing slab centerline‐microporosity distance, the microporosity minimization effect of HR becomes poor. When the axial ratio (long axis/short axis) is 1.43, the microporosity closure is the largest, and the porosity closure is the highest when the long axis is perpendicular to the reduction direction. When the total segment reduction is constant, the reduction mode with gradually decreasing reduction results in the highest total porosity closure and minimum reduction force. [ABSTRACT FROM AUTHOR]

To reduce the burning loss and the spalling and to improve energy efficiency, the mullite composite lining plates were used to replace cast steel or alloy lining in rotary coke tanks for coke dry quenching equipment. The results show that: the dense mullite composite lining plate in the cone part has the density of 2.20 g·cm-3 and the wear test, s volume loss of 4.08 cm3, and the light weight mullite composite lining plate in the straight cylinder part has the density of 1.95 g·cm-3 and the wear test, s volume loss of 17.6 cm3. After using, there is no shrinkage gap, no burn loss or holes in the plates, indicating good sealing of the mullite composite lining plates. The lining plate for the cone part has low burning loss, without spalling for more than half a year. The outer surface temperature of coke tanks adopting the cast steel or the alloy lining is 480 to 570 °, while that of the ones adopting mullite composite lining plates is 120 to 170 °, showing a largely improved insulating property. Adopting mullite composite lining plates on the basis of the current coke tank cage, the lining plates can be timely treated and wholly replaced, improving the service life and reducing the maintenance workload. [ABSTRACT FROM AUTHOR]

Currently there is greater interest and an industrial need to create a bond between cast steel and aluminum alloys. The bond quality between these two metals must be considered, since it is affected by several casting techniques and parameters. This research aims to find the right combination of techniques and parameters to make a good bond between cast steel and aluminum alloys. This research systematically used the response surface methodology (RSM). Three important casting techniques and parameters are selected as independent variables, which are preheating temperature of cast steel, pouring temperature of aluminum alloy molten, and surface cleaning of cast steel. The gap between cast steel and aluminum alloy is used as dependent variable, which is defined as the quality measurement of the bond between two metals. The experiments were conducted on 48 samples, in which destructive test was performed in order to measure the gap. From the methodology, it is found that the recommended preheating temperature of cast steel is 491 °C, the recommended pouring temperature of aluminum alloy is 696 °C, and the recommended technique is cleaning the cast steel insert using degreasing. For practical purpose, the preheating temperature of cast steel can be set at 490 ± 10 °C and the pouring temperature of aluminum alloy can be set at 695 ± 10°C. This research limits on bimetal casting between cast steel and aluminum alloys, and the casting process is gravity die casting process. This paper is able to find the best casting techniques and parameters for cast steel and aluminum alloy bond using RSM. This paper also proposes gap bond between two metals as bond quality measurement. [ABSTRACT FROM AUTHOR]

Stellite 20 layers were clad onto a ZG230-450 cast steel substrate by laser cladding with different content of Nb in the Stellite 20 powder. The microstructure evolution, phase composition, microhardness and wear properties of the laser clad Stellite 20 were studied systematically. The results showed that the phases in the laser clad Stellite 20 layers were mainly 1-Co, FeCox, M23C6, Cr3C2, CoxNb, M7C3 and NbC. The NbC phase formed in situ significantly refined the microstructure in the laser clad Stellite 20 layer. The microhardness and wear resistance of the laser clad Stellite 20 layer increased gradually with the increasing of Nb content. When the 13% Nb powders were added the microhardness of the laser clad Stellite 20 layer was 1050 HV0.5 which is about 7½ times that of the ZG230-450 cast steel substrate. Also, the wear resistance was improved to about 10.6 times that of the ZG230-450 cast steel substrate. [ABSTRACT FROM AUTHOR]

Rail defects such as fatigue cracks have been one of the leading root causes of a number of derailments in the past. Cracks that initiate and propagate below the surface are difficult to detect using traditional non-destructive testing (NDT) methods. Acoustic emission (AE) is a more effective method for detecting and monitoring crack growth in rails online. This study investigates the applicability of AE for quantifying damage propagation in austenitic cast manganese steel used in manufacturing railway turnouts. The relationship between AE and crack growth rate in austenitic cast manganese steel samples that were fatigue tested in a three-point bending configuration was investigated by evaluating the AE activity with respect to direct current potential drop (DCPD) measurements and scanning electron microscopy (SEM) fractographic analysis of the tested samples. From the results obtained, it was not possible to observe a clear relationship between AE activity and the actual crack growth rate. Based on the SEM fractographic analysis, this is likely due to the plasticity occurring at the tip of the fatigue crack in the tested samples. This is plausible since the cast manganese steel samples had been cut off from a plate that had not been previously work hardened. The effect of carbides present in the microstructure is an additional contributing factor. Further tests should be carried out on cast manganese steel samples that have been work hardened prior to fatigue testing. [ABSTRACT FROM AUTHOR]

The present study designed two kinds of Fe-18Mn-1.3C-2Cr-(4, 11)Al (wt.%) low-density steels. Tensile and impact tests were carried out to evaluate the work hardening and impact toughness properties via aluminum (Al) alloying control. Meanwhile, microstructure evolution and fracture morphology were investigated by X-ray diffraction (XRD), a scanning electron microscope (SEM) equipped with electron backscatter diffraction (EBSD), a transmission electron microscope (TEM), and a stereo-optical microscope (OM). It is found that the Al addition obviously promotes the dislocation planar slipping, resulting in cleavage and brittle impact fracture in 11wt.% Al steel. Besides, the microband-induced plasticity (MBIP) mechanism is found in 4wt.% Al containing steel, introducing considerable work hardening capacity and impact toughness of 156.8±17.4 J. The present study provides a direct illustration of the relationship between work hardening and impact toughness behaviors of these two low-density steels for potential application as impact-resistant components. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the resistance of cast duplex (austenitic-ferritic) steels to pitting corrosion with respect to the value of PREN (Pitting Resistance Equivalent Number). Pitting corrosion is one of the most common types of corrosion of stainless steels. In most cases, it is caused by the penetration of aggressive anions through the protective passive layer of the steel, and after its disruption, it leads to subsurface propagation of corrosion. The motivation for the research was a severe pitting corrosion attack on the blades of the gypsumcalcium water mixer in a thermal power plant operation. In order to examine the corrosion resistance, 4 samples of 1.4517 steel with different concentrations of alloying elements (within the interval indicated by the steel grade) and thus with a different PREN value were cast. The corrosion resistance of the samples was evaluated by the ASTM G48 – 11 corrosion test in a 6% aqueous FeCl3 solution at room and elevated solution temperatures. To verify the possible effect of different alloying element concentrations on the mechanical properties, the research was supplemented by tensile and Charpy impact tests. Based on the results, it was found that a significant factor in the resistance of duplex steels to pitting corrosion is the temperature of the solution. For the components in operation, it is therefore necessary to take this effect into account and thoroughly control and manage the temperature of the environment in which the components operate. [ABSTRACT FROM AUTHOR]

The aim of this work was to characterize the microstructure and properties of cast steel after austempering heat treatment, which would make it possible to produce a carbide-free nanobainite. In order to design heat treatment parameters, dilatometric measurements of phase transformation kinetics were performed on cast steel samples. This study made it possible to construct a time-temperature-transformation diagram and to design the heat treatment parameters. Following this, the most suitable heat treatment parameters were chosen. The heat treatment consisted of austenitizing, followed by quenching with an isothermal stop at the temperature at which bainitic transformation occurred, and final quenching to room temperature. Four different durations of austempering were used at the same temperature of 250 °C to obtain a 55, 75, 85 and 100 pct degree of advancement of bainitic transformation. After 55 and 75 pct bainitic transformation, a martensitic transformation occurred in the remaining austenite during quenching to room temperature. In these cases, a partitioning process consisting of additional annealing at 250 °C, was then applied This kind of heat treatment has not been used in cast steel earlier All heat-treated samples were subjected to microscopic studies at various scales of observation with the use of light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The observations revealed that the heat treatment produced a strongly refined multiphase microstructure and revealed its dependence on the austempering duration. The obtained microstructures provided high tensile strength, however toughness strongly depended on applied heat treatment parameters. [ABSTRACT FROM AUTHOR]

In this paper, the system response, stress redistribution, failure mode, and catenary effect of steel frames with circular tube columns and cast steel stiffener (CSS) joints under a sudden column removal scenario were revealed. Based on this force transfer mechanism analysis, a practical and computationally efficient component-based model considering catenary effects and CSS joint details with a series of springs was established and validated by a detailed solid-element method. By using this component-based model, the proper dynamic response increase factor of the CSS joint frames was investigated. The results show that the great overall stiffness and strength of the CSS limit the deformation of the column front shell. Therefore, the CSS joint frames have superior performance for progressive collapse prevention than the frames using welded joints without stiffeners. In addition, the component-based model is validated to be effective and the dynamic response increase factor of the frames with circular tube columns and CSS joints is smaller than 2.0. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the effect of zone reinforcement of cast steel L120G13 with Al2O3 macro-particles on the corrosion resistance of the composite obtained in this way. The obtained results allow us to conclude that strengthening of cast steel with corundum, the aim of which was to significantly increase the abrasive wear resistance, did not significantly deteriorate corrosion resistance. SEM tests show that a permanent diffusion layer interface is formed at the boundary between cast steel and corundum. In this area, simple manganese segregation and reverse iron and chromium segregation were found. These elements pass from the liquid alloy to the surface layer of the corundum particles, causing the aluminium and oxygen to be pushed deep into the corundum grains. Corrosion tests indicate comparable corrosion resistance of cast steel L120G13 and the composite L120G13 + Al2O3. Moreover, no intergranular corrosion was found in the matrix of the composite and no signs of pitting corrosion were found in the areas of the interface between the phases of the composite. This information is extremely important from the point of view of the material's service life. Observations of breakthrough of both materials obtained during fracture after potentiodynamic corrosion tests, immediately after freezing in liquid nitrogen, indicate cracking with plastic features and increased resistance to dynamic forces of cast steel L120G13 and the composite L120G13 + Al2O3. [ABSTRACT FROM AUTHOR]

The paper describes the experience of repair welding of service defects in the body of the connecting rod of mobile jaw crusher Metso lokotrack LT 120, which is a rather rigid honeycomb structure from cast low-alloyed steel of 20GL type with thickness of external walls of 60 mm and of partitions of not less than 45 mm and more than 5 t weight. It was found that the most signifi cant defects – fatigue cracks and cleavage which are incompatible with performance, naturally formed near the structural stress raisers, service damage, caused by contact impact of armour protection, casting defects, as well as in the sites of unsmooth connection of elements, etc. Crack opening displacement is equal to 2…3 mm that is indicative of the start of shape change of the body and need for prevention of further operation in such a state. Rigid structure of the connecting rod body and general state of destruction required special technology of repair welding, which was created and realized by the authors. It included new welding materials, technological measures and engineering solutions and those verifi ed by our own practical experience of repair of cast structures, as well as high skill and competence of the welders. Practical importance and eff ectiveness of the performed work on connecting rod repair was confi rmed by safe operation of the crusher in the design mode for two years. 9 Ref., 3 Tabl., 8 Fig. [ABSTRACT FROM AUTHOR]

The paper describes the experience of repair welding of service defects in the body of the connecting rod of mobile jaw crusher Metso lokotrack LT 120, which is a rather rigid honeycomb structure from cast low-alloyed steel of 20GL type with thickness of external walls of 60 mm and of partitions of not less than 45 mm and more than 5 t weight. It was found that the most significant defects -- fatigue cracks and cleavage which are incompatible with performance, naturally formed near the structural stress raisers, service damage, caused by contact impact of armour protection, casting defects, as well as in the sites of unsmooth connection of elements, etc. Crack opening displacement is equal to 2-3 mm that is indicative of the start of shape change of the body and need for prevention of further operation in such a state. Rigid structure of the connecting rod body and general state of destruction required special technology of repair welding, which was created and realized by the authors. It included new welding consumables, technological measures and engineering solutions and those verified by our own practical experience of repair of cast structures, as well as high skill and competence of the welders. Practical importance and effectiveness of the performed work on connecting rod repair was confirmed by safe operation of the crusher in the design mode for two years. [ABSTRACT FROM AUTHOR]

Quantifying the pressure distribution and flow rate in the metal delivery system from the tundish to the mold is important to understand nozzle clogging due to air aspiration, argon bubble size, and other important phenomena in continuous casting of steel. A one-dimensional pressure energy model, PFSG, is presented here to calculate pressure distribution and flow rate in slide-gate nozzle systems for argon-molten steel flow systems including argon gas expansion by solving a system of Bernoulli equations. PFSG is a user-friendly MATLAB-based software package with an intuitive Graphical User Interface capable of inverse solutions that enables users to conduct parametric studies in seconds. The model predictions is verified with computational fluid dynamics simulations and validated with plant measurements and water model measurements, with errors of less than 6 pct. The verified and validated PFSG model is then applied to investigate the effect of different casting conditions on the flow rate and pressure distribution. For a given slide gate opening, the flow rate increases with increasing distance from the tundish level to the mold level, increasing SEN diameter, and decreasing argon gas injection rate. The slide-gate opening fraction that produces the minimum pressure is almost independent of casting conditions, except for SEN bore diameter. This critical opening fraction, which is most detrimental for air aspiration, increases from 50 to 70 pct with increasing SEN diameter by 13 pct for the system studied. The minimum pressure worsens (decreases) with increasing tundish height and/or nozzle bore diameter. [ABSTRACT FROM AUTHOR]