Casting Process Research Articles

Behavior of backfill material made of high-water material and recycled concrete lumps for highwall mining

The highwall mining technique is the family member of green mining system, for which the development of the cost-effective backfill material is always the critical issues to be accounted for. In the present research, an innovative backfill material made of the high-water material and recycled concrete lumps was introduced. A total of 42 specimens with variable configurations were prepared and tested to evaluate the effects of the water-to-powder of the high-water material and particle size of concrete lumps on the compressive behaviour of the developed backfill material. Both the acoustic emission (AE) and the digital image correlation (DIC) instruments were applied to investigate the progressive failure modes of tested specimens in parallel. Test results revealed that the high-water material cemented recycled concrete present an ideal ductility when it is subjected to the uni-axial compressive loading, which is different from normal backfill materials featured with brittleness in natural. It also suggested that the effect of the water-to-power ratio of the high water material is much more obvious than that of the lumps size on the enhancement of deformation ability. In terms of the peak strength, these specimens with the 20 mm to 35 mm lumps is higher than that of its counterparts, which suggested that the lump size is one of the most important factor during the design of the proposed backfill material. Moreover, the peak strength of specimens with the small water-to-powder ratio (i.e., 0.75) surpasses those with ratios of 1.0 and 1.25 by 20.4 % and 29.5 %, respectively. Although the specimens with smaller water-to-powder ratio of high water material exhibited the higher compressive strength, it should be noted that the reduced flowability of which will affect the casting process in turn. Research outcomes obtained from this study is expected to facilitate the wide application of the highwall mining.

Direct Precursor Route for the Fabrication of LLZO Composite Cathodes for Solid-State Batteries.

Solid-state batteries based on Li7La3Zr2O12 (LLZO) garnet electrolyte are a robust and safe alternative to conventional lithium-ion batteries. However, the large-scale implementation of ceramic composite cathodes is still challenging due to a complex multistep manufacturing process. A new one-step route for the direct synthesis of LLZO during the manufacturing of LLZO/LiCoO2 (LCO) composite cathodes based on cheap precursors and utilizing the industrially established tape casting process is presented. It is shown that Al, Ta:LLZO can be formed directly in the presence of LCO from metal oxide precursors (LiOH, La2O3, ZrO2, Al2O3, and Ta2O5) by heating to 1050°C, eliminating the time- and energy-consuming synthesis of preformed LLZO powders. In addition, performance-optimized gradient microstructures can be produced by sequential casting of slurries with different compositions, resulting in dense and flat phase-pure cathodes without unwanted ion interdiffusion or secondary phase formation. Freestanding cathodes with a thickness of 85µm, a relative density of 95%, and an industrial relevant LCO loading of 15mg show an initial capacity of 82 mAh g-1 (63% of the theoretical capacity of LCO) in a solid-state cell with Li metal anodes, which is comparable to conventional LCO/LLZO cathodes and can be further improved in the future.

A novel Zr-based metallic glass composite and its plasticizing mechanism

A novel Zr-based metallic glass composite was prepared utilizing a die casting process in this study. This composite utilizes high-porosity open-pored foam metal as the second phase and takes advantage of the unique distribution characteristics of this phase to achieve structural characteristics resembling hard regions surrounded by soft regions. This facilitates the formation and interleaving of numerous shear bands during the deformation process of the composite, resulting in work-hardening capability and favorable compressive plasticity. The results indicate that the compressive strength of the metallic glass composites containing 2.72 % foamed Ni and 3.71 % foamed Cu respectively does not decrease significantly compared to single-phase metallic glass, while their compressive plasticity increases from 1.60 ± 0.46 % to 12.21 ± 1.04 % and 13.01 ± 1.15 %, respectively. This study not only uncovers the preparation method and plasticizing mechanism of a novel metallic glass composite, but also offers a fresh perspective for the design of high-plasticity metallic glass composites.

Tannic acid-reinforced soy protein/oxidized tragacanth gum-based multifunctional hemostatic film for regulation of wound healing

With recent advances in the field of tissue engineering, composite films with biocompatibility, antimicrobial properties, and wound healing properties have gained potential applications in the field of wound dressings. In this research work, composite films of soy protein (S)/oxidized tragacanth gum (G) were successfully made using the solution casting process. The metal-organic framework containing curcumin (MOF) with concentrations of 5 and 10 wt% and tannic acid (TA) with concentrations of 6 and 12 wt% were entered into the polymer film. Surface morphology with scanning electron microscope (FE-SEM), thermal stability, mechanical properties, chemical structure, antioxidant, water absorption, cell viability, antibacterial activity, and biodegradability of the prepared films were investigated in laboratory conditions. In addition, the toxicity of the films in the cell environment was investigated, and the results showed that cell growth and proliferation improved in the presence of the prepared films, especially films SG/MOF10/TA6 and SG/MOF10/TA12 due to the presence of TA and MOF containing curcumin. Also, the antibacterial activity of the films showed that the presence of tannic acid and curcumin in the structure of the films increases their ability against pathogens. According to the obtained results, the newly produced nanocomposite film (SG/MOF10/TA12) has a high potential to be used for wound dressing due to its favorable characteristics and was considered the optimal film.

The application of the state-of-the-art turbulence models in the OpenFOAM CFD codes and the validation for different flow control cases in the continuous casting process

Computational fluid dynamics (CFD) is an established approach to study flow behaviour. Despite advances in mathematical numerical modelling in recent decades, accurately predicting the turbulent flow behaviour of steel using CFD remains a challenge. In the continuous casting process, two main flow control systems are employed to transfer liquid steel from the tundish to the mould, namely stopper control and slide gate control. In additional to these two main flow control systems, the casting nozzle geometries, casting rate, and casting mould dimensions vary considerably, and this complexity makes it difficult to precisely simulate turbulent flow in the casting channel. In this paper, examples are presented showing how different turbulence models influence the simulation results, using the latest version of the open source CFD simulation software OpenFOAM. Prior to the CFD modelling, RHI Magnesita's water modelling facilities in Leoben (Austria) were used to validate the state-of-the-art turbulence models selected for a particular casting nozzle geometry and flow control system.

Tensile, flexural and fatigue properties of different thermoplastic nanocomposites: experimental investigation and ANN prediction of the fatigue life

ABSTRACT Polymer-based nanocomposites have received immense attention in industrial applications as their mechanical properties are superior to traditional polymer composites. In this study, three different thermoplastic polymers, namely (a) polypropylene (PP), (b) acrylonitrile butadiene styrene (ABS), and (c) high-density polyethylene (HDPE) were used for the purpose of engineering different nanoclay-based nanocomposites. The blending of the polymer was performed by varying the nanoclay weight percentage (0.5, 1, 3, and 5 wt.%) using a twin-screw extruder. The different nanocomposites were fabricated through injection moulding process. The composites were fabricated by considering the 90 bars of injection pressure, 60 mm/s of injection speed, and 25 sec of cooling time. The effect of nanoclay inclusion on the mechanical properties of the nanocomposites was evaluated and compared with the neat polymer. The effect of nanoclay inclusion was studied through morphological analysis of the fractured tested specimens. The tensile strength and modulus of ABS-nanoclay (5%) exhibited an enhancement of 30.95% and 35%, respectively as compared to the pure ABS. Meanwhile, the fatigue life revealed an improvement of 66.01%. The tensile strength and modulus of the ABS/nanoclay (5%) were achieved as 38.6 MPa and 1.44 GPa.

CP-RDM: a new object detection algorithm for casting and pouring robots

Abstract Automating the casting sector heavily relies on pivotal technology for object detection in pouring robots. A sophisticated algorithm designed to identify and locate target pouring holes in intricate casting workshops is crucial for advancing the intelligence of the casting process. However, the workshop environment for pouring is generally challenging, with uneven lighting, varying sizes of pouring holes, and significant occlusion in the target area, all impacting the accuracy of target detection tasks.
To overcome these challenges, this paper proposes enhancing the YOLOv8s algorithm for object detection in pouring robots. Firstly, to address the issue of different scales in pouring holes, a Multi-Scale Residual Channel and Spatial Information Fusion Module (MRCS) is designed to aggregate channel and spatial information, thereby enhancing the feature extraction capability of the model. The proposed enhancement is validated on the Pascal VOC dataset. Secondly, a SimAM attention mechanism is added at the end of the backbone network to focus the object detection network more on the positional region of the pouring hole. Importantly, this addition does not introduce extra parameters or computational burden to the model.
Finally, in the detection part of the model, the detection head from the RT-DETR model is introduced. This combination of real-time detection capability from YOLO and deep feature extraction capability from RT-DETR enhances the detection accuracy of the model while ensuring real-time performance. Experimental results on the updated pouring hole dataset reveal that, with only a slight increase in parameters, the proposed model achieves a 2.5% and 3.5% improvement in mAP@0.5 and F1-Score, respectively, compared to the baseline algorithm YOLOv8s. Precision (P) is enhanced by 1.8%, recall (R) by 3.5%, and PFS reaches 110, meeting the requirements for real-time pouring in pouring robots.

Development of Replica Molding Processes for Hypervariable Microstructural Components

Development of Replica Molding Processes for Hypervariable Microstructural Components

Microstructure phase analysis and process optimization of ZL205A metal mold casting

In this paper, we take an elastomeric transmission structure part made of ZL205A alloy as the research object, and use the metal type gravity casting technology for casting trial production, analyze the quality and mechanical properties of the molded parts of ZL205A alloy parts under different process parameters, optimize the casting process parameters, get the optimal combination of process parameters, and obtain large ZL205A castings with less internal quality defects and high mechanical properties.

Achieving significant grain refinement efficiency in Mg-Al alloys via a GNP@MgO composite refiner

Master alloys containing Zirconium (Zr) serve as effective grain refiners in most commercial cast magnesium (Mg) alloys. However, their efficacy is diminished in Mg–Al series alloys due to the formation of Al–Zr compounds. In this work, a novel Mg-GNP@MgO master alloy was prepared utilizing the in-situ reaction between CO2 and Mg. The grain refinement efficiency of this composite inoculation on Mg–9Al alloys was systematically investigated using SEM-EBSD, HRTEM observations, Density Functional Theory (DFT), and Sharp Interface Model (SIM) calculations. The findings suggest that the composite grain refiner (GNP@MgO) exerted a notable refining influence on Mg–9Al alloy. Through the conventional casting process, the average grain size was refined to approximately 13 μm upon the addition of 3 vol% GNP@MgO, achieving a grain refinement efficiency of 90 %. The enhanced refining efficiency arises from the synergistic control over the nucleation and growth processes of α-Mg grains, facilitated by GNP@MgO particles. This process includes improved heterogeneous nucleation, triggered by the newly formed Al4C3 phases through the interaction between GNPs and Al element, followed by the limited expansion of α-Mg grains induced by the nano-sized MgO particles. The MgO particles predominantly gather around grain boundaries to establish stable nano-coating layers, thereby exerting a substantial Zener pinning effect. The pinning role played by the MgO nanoparticles was also verified by a sharp interface model. The findings in this work not only carve out a new avenue for the grain refinement of cast Mg–Al alloys but also inspire fresh perspectives for the development of novel grain refiners.

The effect of differing Y concentrations on the evolution of the structure and mechanical properties of FeCrAl alloy

The influence of different Y concentrations on the evolution of the structural and mechanical properties of FeCrAl alloys is investigated in this work. The ingot casting process was used to produce alloys with Y mass fractions of 0%, 0.03%, and 0.25%, respectively. They were then annealed for 15 min at 850°C, 950°C, and 1050°C before being quenched by water to room temperature. Microstructure and mechanical properties were analyzed using OM, EPMA, EBSD, and tensile tests. The addition of 0.03% Y to FeCrAl alloy and annealing at 850°C resulted in the greatest overall performance of the alloy. This had a tensile strength of 635.62 MPa, yield strength of 465.48 MPa, and elongation of 27.04%. With an increase in Y concentration or annealing temperature, the tensile, yield, and elongation properties decrease. This phenomenon can be attributed to the incorporation of Y, which creates a fine Y-rich second phase in the alloy. These phases act as heterogeneous nuclei, pinning the grains during solidification, effectively reducing grain growth and refining the grains. Grain refinement and an increase in the number of grain boundaries hinder dislocation movement, thereby enhancing the alloy's tensile and yield strength. Simultaneously, this prevents the disappearance of α-fiber textures and the creation of γ-fiber textures during recrystallization and reduces the strength of the γ-fiber textures in the alloy microstructure. However, as the annealing temperature increases, microstructure grain growth and the number of grain boundaries decrease. Moreover, higher Y concentrations result in the formation of large, striated Fe-Y phases, which impair the forming properties of the alloy and consequently reduce its tensile properties. Therefore, future research should focus on effectively avoiding the formation of coarse second phases in the microstructure of FeCrAl alloy to enhance its overall performance.

Effects of mineral additions on the rheology of self-compacting concrete: a review

The rheological study of concrete is crucial for the construction sector because of its influences on the casting process and hardened properties. This is even more important when designing and producing self-compacting concrete (SCC). By controlling yield stress and plastic viscosity, it is possible to predict and optimise the flowability of SCC. Understanding the rheological behaviour of SCC is a major step in achieving adequate flow behaviour to fill the formwork without any sign of segregation or blockage and hence yielding satisfactory performance of hardened concrete. This paper provides a critical and detailed review on rheological properties of SCC based on studies published in recent years. The rheological models for characterising the flow behaviour of fresh concrete are briefly assessed. The influence of water to cementitious materials ratio on SCC properties is also discussed. A comprehensive review on the influence of fine additions (i.e. fly ash, ground blast furnace slag, silica fume, metakaolin and limestone powder) on SCC rheology has also been presented in this review.

Large eddy simulation of various EMBr effects on the fluid flow, heat transfer and solidification process in an ultra-high speed thin slab casting mould with multi-port SEN

Effective control of intense turbulence is a crucial challenge for achieving steady production with ultra-high casting speed in thin slab continuous casting. In thin slab casting process, specially designed multi-port submerged entry nozzle (SEN) with four outlets is utilised to ensure an ample supply of molten steel, necessitating the selection and optimisation of suitable Electromagnetic Braking (EMBr) equipment for steel jet control. This study established a comprehensive three-dimensional model of a funnel-type mould, employing a combined experimental-numerical approach to validate and investigate the flow, heat transfer, solidification and electromagnetic behaviour in the mould. The steel grade studied in the simulation is Q235B, and its physical properties were calculated based on its composition with a temperature range of 1450–1826 K. To analyse the influence of high casting speed on the flow and solidification behaviour in the mould, three casting speeds were selected for the study, which were 6, 7 and 8 m/min. The results indicate that the novel Bowl EMBr significantly suppressed the penetration of steel jet and thus enhanced the thickness and uniformity of the solidified shell. As the casting speed increases from 6 to 8 m/min, the solidified shell thickness at the mould exit decreases from 7.91 to 5.94 mm, with the stagnant growth region approaching the mould exit. This highlights the requirement to correspondingly increase EMBr strength under ultra-high casting speed condition to avoid remelting of the shell and the risk of molten steel leakage. The coupled mathematical model established in this study provides guidance for optimising EMBr structures and casting speed under special multi-port SEN conditions, offering recommendations for the rational control of flow, heat transfer and solidification process in the mould.

Simulation Model of a Steelmaking-Continuous Casting Process Based on Dynamic-Operation Rules.

The steelmaking-continuous casting process (SCCP) is a complex manufacturing process which exhibits the distinct features of process manufacturing. The SCCP involves a variety of production elements, such as multiple process routes, a wide array of smelting and auxiliary devices, and a variety of raw and auxiliary materials. The production-simulation of SCCP holds a natural advantage in being able to accurately depict the intricate production behavior involved, and this serves as a crucial tool for optimizing the production operation of the SCCP. This paper thoroughly considers the various production elements involved in the SCCP, such as the fluctuation of the converter smelting cycle, fluctuation of heat weight, and ladle operation. Based on the Plant Simulation software platform, a dynamic simulation model of the SCCP is established and detailed descriptions are provided regarding the design of an SCCP using dynamic-operation rules. Additionally, a dynamic operational control program for the SCCP is developed using the SimTalk language, one which ensures the continuous operation of the caster in the SCCP, using the discrete simulation platform. The effectiveness of the proposed dynamic simulation model is verified by the total completion time of the production plan, the transfer time of the heat among the different processes, and the frequency of ladle turnover. The simulation's results indicate that the dynamic simulation model has a satisfactory effect in simulating the actual production process. On this basis, the application effects of different schedules are compared and analyzed. Compared with a heuristic schedule, the optimized schedule based on the "furnace-machine coordinating" mode reduces the weighted value of total completion time by 8.7 min, reduces the weighted value of transfer waiting time by 45.5 min, and the number of rescheduling times is also reduced, demonstrating a better application effect and verifying the optimizing effect of the "furnace-machine coordinating" mode on the schedule.

Effect of Fe Element and Ultrasonic Vibration on the Microstructure and Mechanical Properties of the Cu-TiB2 Composites

Cu-(Fe-Ti)-TiB2 composites were prepared by in situ reaction and vacuum casting with and without ultrasonic vibration. The evolution of the microstructure and mechanical properties of the composite with the variation in Fe element was analyzed. The import of Fe elements could purify the matrix after in situ reaction and the formation of a nanoprecipitated phase, thus improving the strength of Cu-Fe-Ti-TiB2 composites. Meanwhile, compared with the traditional casting process, the Cu-Fe-Ti-TiB2 composites with ultrasonic vibration treatment exhibit uniform TiB2 particle distribution and better properties. The tensile strength and uniform elongation of the composite with a Fe content of 0.7 wt.% reached 511 MPa and 6.02%, increasing by 14.3% and 318% compared to the unalloyed composite, respectively. The tensile strength and uniform elongation of Cu-0.7Fe-Ti-TiB2 composite with ultrasonic vibration treatment increased to 533 MPa and 7.16%, respectively. The TiB2 microscale particles and Fe2Ti nanoscale precipitates with uniform distribution effectively impeded dislocation movement and recrystallization, which improved the tensile strength and stability at elevated temperatures.

An insight investigation on mechanical and corrosion behavior of ultrasonic squeeze casting processed Mg based alloy composites for bio-implantation

Magnesium (Mg) alloys are gaining prominence in the bio-implantation process due to their low weight, high strength, greater compatibility and ease of biological degradability. However, poor strength and rapid degradation in the physiological environment inhibit their application as implant material. The present experimental investigation examines the effect of Zirconium oxide (ZrO2) reinforcement on mechanical and corrosion behaviors of Mg - Tin (Sn) alloy composites, for assessing their feasibility in the targeted field. Mg-5%ZrO2, Mg-1%Sn, and Mg-1%Sn/5 % ZrO2 were fabricated via ultrasonic aided squeeze casting (UASC) process. Characterization studies on the synthesized composites were carried out to evaluate their morphology using SEM with EDAX and XRD. Mechanical properties were evaluated using micro-hardness and compression tests. Furthermore, the corrosion behavior was determined using Tafel and electrochemical impedance spectroscopy (EIS). The results revealed that the Mg alloy bio-composite (Mg-1%Sn/5 % ZrO2) exhibits better compression (291.2 MPa) and yield (215.3 MPa) strength, elastic modulus (55.7 GPa), hardness (941.4 MPa) and reduced corrosion rate (0.475 mm/yr) than the base Mg and non-reinforced Mg bio-composite (Mg-1% Sn). Overall, the newly synthesized ZrO2 reinforced Mg bio-composite would potentially be used as a bio-implantation supportive material in bone fracture related treatments.

A versatile steel belt casting equipment for in situ synchrotron radiation x-ray scattering measurement of polymer films.

A steel belt casting equipment, weighing approximately ∼6-7 tons and measuring ∼5m in length, has been designed and developed for simulating the industrial processing of polymer films and being combined with synchrotron radiation in situ x-ray scattering measurements. Through modification of its modules, it is feasible to implement two distinct film casting modes, namely the wet and the dry casting processes. The speed of a steel belt can span from 0.5 to 8 m/min. The highest experimental temperature and drying wind speed are 300 °C and 6m/s, respectively. All film casting parameters, such as extrusion speed, distance between die and steel belt, casting speed, temperature, and wind speed, can be adjusted independently. Especially, the control accuracy of the temperature and casting rate can reach ±0.1 °C and ±0.01 m/min, respectively. The feasibility of this equipment has been validated through in situ x-ray scattering tests at the BL10U1 industrial beamline of the Shanghai synchrotron radiation facility. With the assistance of this equipment, the understanding of the physical mechanism behind the film casting process should be improved so that the development of advanced functional polymer films.

The temperature field characteristics and amorphous formation ability during the continuous casting process of Zr-based bulk metallic glass

This study utilized FLUENT dynamic mesh simulation technology to simulate the temperature field distribution characteristics during the continuous casting (CC) process of 5 mm thick Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (Vit1) bulk metallic glass (BMG), analyzed and discussed the amorphous forming ability of the Vit1 BMG plate prepared through CC. The results indicate that during the CC process, the temperature gradient and cooling rate of Vit1 BMG plate decrease with increasing distance from the cooling copper block surface and prolonged solidification time. Even at the lowest cooling rate, it still remains significantly higher than the critical cooling rate (Rc) of Vit1 bulk amorphous alloy. The temperature variations recorded by the thermocouple during the alloy melt solidification process are in basic agreement with the simulation data. The experimental test and simulation results show that 5 mm thick Vit1 BMG slab can be prepared theoretically by continuous casting technology. Finally, XRD, DSC and TEM were used to analyze the amorphous formation ability and microstructure of the Vit1 BMG slab.

Stress state of billet – mandrel system during production of hollow steel billet in a unit of continuous casting and deformation. Part 2

The paper presents the results of theoretical research of stress-strain state of a billet – mandrel system when producing steel hollow billets in a unit of combined continuous casting and deformation, in which the working surface of the calibrated anvils are made with a variable radius. The necessity of making the working surface of the calibrated anvils with a variable radius is substantiated and initial data for the calculations is given. The calculation results are considered along the lines of the volumetric model passing through the characteristic points of deformation centers. The authors determined the forces when the anvils compress the wall of a hollow billet and the force of pulling the hollow billet from the mold. The laws of metal axial displacements and stresses in the deformation centers during compressing the wall of a hollow billet was established at the combined process of continuous casting and deformation in the unit. Nature of the stressed state of the metal wall of a hollow billet is considered from the perspective of improving its quality. The technique studied allows to determine the stress-strain state of a mandrel when producing a hollow steel billet using such a unit. The authors provided the recommendations for reliable gripping and compression with calibrated anvils of a hollow steel billet coming from a water-cooled copper mold of the unit of combined continuous casting and deformation.

Defect prediction and performance optimization of A413 vertical centrifugal castings through FEA-based simulation

This study benefits from advanced simulation based on finite element analysis, where finite element analysis possesses robust numerical algorithms to confront critical industrial challenges, including prediction and optimization techniques. The primary goal is to predict the location and quantity of shrinkage porosity and air entrainment, and to mitigate them by optimizing key casting process factors while considering the geometric effects. Virtual experiments designed through the Taguchi method, with three parameters (aspect ratio, pouring temperature, and mold rotation speed) at five levels each, were conducted using the finite element analysis software ProCAST. Post-experimentation, comprehensive data analyses, including signal-to-noise ratio and response surface methods, were employed to determine optimal conditions. Additionally, a sophisticated regression model was developed to clarify the complex relationship between key parameters and defect aspects. Optimal conditions to reduce shrinkage porosity were identified within parameter ranges of (50–75) rpm, (750–800) °C, and (1.75–2) aspect ratio. Similarly, optimal parameters to reduce air entrainment were identified as 150 rpm, 800 °C, and (1) aspect ratio.