Parametric investigation on an industrial electromagnetic continuous casting mould performance

This research aimed at conducting a quantitative investigation of process parameters on the magnetic field contribution in an electromagnetic continuous casting mould. The Taguchi method (4 factors and 3 factor value levels: L9 orthogonal array) was adopted to design matrix of the simulation runs and the analysis of variance was used to evaluate the contributions of each control factor. The simulations were conducted based on the finite element method and the numerical set-up was validated by the designed experiment. The results showed that the applied alternating current magnitude contributed most (76.64%) to the magnetic field level in the mould, compared to the other control factors. It was followed by the slit length (17.72%), the alternating current frequency (4.17%) and the slit width (1.57%)

Modelling shell and oscillation mark formation during continuous casting via explicit incorporation of slag infiltration

The development of reliable numerical models is vital to improve the quality of continuously cast products and to increase the productivity of the casting machine. In order to provide accurate predictions, these models must include detailed descriptions of the physical phenomena occurring inside the mould, such as metal flow, heat transfer and solidification. However, these topics are often treated separately during modelling due to their complexity. This has a negative impact on the accuracy of the predictions. To address this issue, a numerical model capable of coupling the flow dynamics with both the heat transfer to the mould walls and solidification has been developed. The 2‐dimenional model is based on a commercial CFD code that solves the Navier‐Stokes Equations coupled with a Volume of Fluid interface tracking technique for the multiphase system slag‐steel‐air under transient conditions within a conventional slab mould. The use of an extremely fine mesh in the meniscus region (~50 μm) allows, for the first time, the explicit calculation of liquid slag infiltration into the shell‐mould gap. Heat transfer through the solid mould faces and mould oscillation were also included in the model to provide a more realistic representation of the process. The model developed was tested in two case studies. In the first case, the predicted values were compared to prior numerical models and laboratory experiments directed to casting of conventional slabs. Excellent agreement was found for characteristics such as slag film development and heat flux variations during mould oscillation. Furthermore, predicted values for shell thickness, consumption and heat flux were also found to be in good agreement with plant measurements. The findings of this case study provided improved, fundamental understanding of the mechanisms involved in slag infiltration and solidification inside the mould and how these affect key process parameters, such as powder consumption and shell growth. The second case study consisted of a sensitivity study, where casting conditions (e.g. casting speed, mould cooling, steel/slag properties and oscillation settings) were varied in the simulations to determine their effect on both powder consumption and the formation of defects. The simulations predicted the initial formation of typical casting defects known as oscillation marks, without the aid of any external data fitting. The key result drawn from the sensitivity study was the determination of simple rules for the calculation of consumption, heat flux and defect formation as a function of the casting conditions. This opens the possibility of using the model as a diagnostic tool and for process optimisation

Solidification and Gravity VII

International audienc

Electromagnetic measurements of steel phase transformations

This thesis describes the development of electromagnetic sensors to measure the phase transformation in steel as it cools from the hot austenite phase to colder ferritic based phases. The work initially involved investigating a variety of sensing configurations including ac excited coils, C-core arrangements and the adaptation of commercial eddy current proximity sensors. Finally, two prototype designs were built and tested on a hot strip mill. The first of these, the T-meter was based on a C-shaped permanent magnet with a Gaussmeter measuring the magnetic field at the pole ends. Laboratory tests indicated that it could reliably detect the onset of transformation. However, the sensor was sensitive to both the steel properties and the position of the steel. To overcome this, an eddy current sensor was incorporated into the final measurement head. The instrument gave results which were consistent with material property variations, provided the lift off variations were below 3Hz. The results indicated that for a grade 1916 carbon- manganese steel, the signal variation was reduced from 37% to 2%, and the resulting output was related to the steel property variations. The second of these prototypes was based on a dc electromagnetic E-core, with Hall probes in each of the three poles. 'Cold' calibration tests were used to decouple the steel and the lift-off. The results indicated that there was an error of 3-4% ferrite/mm at high ferrite fractions. At lower fractions the error was higher due to the instrument’s insensitivity to lift-off. The resulting output again showed a relationship with varying steel strip properties. ft was also shown that a finite element model could be calibrated to experimental results for a simple C-core geometry such that the output was sensitive to 0.2% of the range. This is required to simulate the sensor to resolve to 10% ferrite

Annual Report 2018-2019

It contains the statement of R&D works undertaken, achievement made and the expenditure by the laboratory during the financial year 2018-2019

Ultrasonic Cavitation Treatment of Metallic Alloys

This Special Issue scrutinizes the use of ultrasonic-cavitation melt treatment in technology of high-quality metallic alloys with improved mechanical properties, and assesses the driving mechanisms of cavitation-induced effects, such as grain refinement, degassing, wetting, and particle distribution. In this context, the research published in this Special Issue considers the interaction between the cavitation field and acoustic streaming with the melt flow and the suspended solid/liquid phases, the characterization and mapping of cavitation activity in a melt volume, and the possibility of achieving high efficiency in processing large melt volumes through technological approaches for the commercial implementation of ultrasonic processing technology

MATLAB

This excellent book represents the final part of three-volumes regarding MATLAB-based applications in almost every branch of science. The book consists of 19 excellent, insightful articles and the readers will find the results very useful to their work. In particular, the book consists of three parts, the first one is devoted to mathematical methods in the applied sciences by using MATLAB, the second is devoted to MATLAB applications of general interest and the third one discusses MATLAB for educational purposes. This collection of high quality articles, refers to a large range of professional fields and can be used for science as well as for various educational purposes

Continuous monitoring of elastic modulus of mortars using a single-board computer and cost-effective components

The Elastic Modulus Measurement through Ambient Response Method (EMM-ARM) is designed to continuously monitor the elastic modulus of hardening construction materials such as concrete, cement paste, mortars, stabilized soils, and epoxy resin. In practice, a composite beam, made of the tested material in its mould, is induced to vibration by means of environmental or controlled excitation, and its resonant frequency is identified. The material’s elastic modulus can then be calculated based on the vibration equation of structural systems. The traditional system to conduct EMM-ARM experiments is based on specialized equipment and on proprietary licensed software, which results in a considerable cost, as well as limited options for customization. The paper hereby presented proposes a delve into the development and validation of a cost-effective and open-source system that is able to conduct EMM-ARM experiments. By using a Raspberry Pi for the computing device and cost-effective electronic components, the cost of the system was one-twentieth of the traditional one, without compromising the measurement reliability. The composite beam’s excitation is generated, while the vibration response is recorded by the proposed system simultaneously, since the Raspberry Pi supports multiprocessing programming techniques. The flexibility earned by the exclusive use of open-source and cost-effective resources creates countless application possibilities for the proposed system.This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D unit of the Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020, and under the Associate Laboratory Advanced Production and Intelligent Systems (ARISE) under reference LA/P/0112/2020. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie project SUBLime [Grant Agreement n. 955986]