Electron Beam Melting and Refining of Metals: Computational Modeling and Optimization

Vutova, Katia; Donchev, Veliko

doi:10.3390/ma6104626

Cited by 15 publications

(12 citation statements)

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“…Therefore, theoretical investigation and application of different approaches-numerical, statistical, heuristic, etc. [4,18,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]-are essential for the understanding and optimization of e-beam melting and refining technology. Consequently, modeling and mathematical optimization of the process parameters are important and key to improving the quality of the obtained pure metal, depending on the concrete characteristic requirements.…”

Section: Introductionmentioning

confidence: 99%

“…Stationary, quasi-stationary, or non-stationary heat transfer models and the numerical study of complex processes at the interaction of intensive electron beams with materials have been reported for different e-beam melting techniques developed to meet some specific requirements [25][26][27][28][29]31,33]. Investigation aided by an e-beam button furnace and a numerical model for studying the electron beam melting of Al (rich)-Ti solids in liquid titanium are presented in [34].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Tantalum Recycling by Electron Beam Melting

Vutova

Vassileva

Koleva

et al. 2016

Metals

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Abstract:Investigations are carried out and obtained experimental and theoretical data for tantalum scrap recycling by electron beam melting (EBM) is presented in this paper. Different thermal treatment process conditions are realized and results are discussed. A chemical analysis is performed and refining mechanisms for electron beam (EB) refining of Ta are discussed. For the performed experiments the best purification of Ta (99.96) is obtained at 21.6 kW beam power for a melting time of 3 min. A statistical approach is applied for estimation of the material losses and the liquid pool characteristics based on experimentally-obtained data. The aim is to improve the EBM and choosing optimal process conditions, depending on the concrete characteristic requirements. Model-based quality optimization of electron beam melting and refining (EBMR) processes of Ta is considered related to the optimization of the molten pool parameters, connected to the occurring refining processes, and to minimal material losses. Optimization of the process of EBM of Ta is based on overall criteria, giving compromised solutions, depending on the requirements concerning the quality of the performed products. The accumulated data, the obtained results, and the optimization statistical approach allow us to formulate requirements on the process parameters.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of Tantalum Recycling by Electron Beam Melting

Vutova

Vassileva

Koleva

et al. 2016

Metals

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“…A mathematical optimization technique, including a proposition for analytical optimization criteria, their discretization according to the numerical scheme and methods for solving the discrete optimization problems, were proposed and applied as well [8]. In this paper, an optimization problem for achieving flatness of the molten pool shape (liquid/solid metal boundary) is proposed.…”

Section: Introductionmentioning

confidence: 99%

“…The criterion is based on calculating the curvature of the liquid/solid boundary which describes the geometry of the molten pool contour and is very important for studying and optimizing the quality of the pure metal obtained after EBMR. The flatness of the liquid/solid boundary is directly connected to the quality of the structure of the metal obtained [3,6,8].…”

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical investigation of the refinement of Hf by EBM

Donchev¹,

Vutova

Vassileva

2014

J. Phys.: Conf. Ser.

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Abstract. Electron beam melting (EBM) in vacuum is one of the most promising technologies for refining and recycling of metals that react with oxygen when heated. Hf is such a metal. Pure Hf (with a small content of gas and metal impurities) is needed for a variety of applications in the aerospace industry and metallurgy, in the production of components of nuclear reactors, microprocessors, optical components etc. We conducted experiments with the ELIT-60 equipment on Hf ingots at electron beam powers of 12, 15, 17 kW and obtained data about the concentration of impurities by the ICP-MS method. For further understanding and optimizing the Hf refining processes, a non-stationary heat model was applied for numerical simulation of the heat transfer processes. Simulation data about the liquid pool variation during the e-beam treatment was thus obtained. The flatness of the crystallization front shape, which is connected to the structure quality, was investigated by optimization criteria related to the curvature of the liquid/solid boundary curve. We also describe an algorithm for calculation of the criteria. One of the criteria was applied to EBM of Hf for different electron beam powers; the results obtained were confirmed by the experimental data. Combining experimental, theoretical and simulation results, a proper technological regime is proposed for better Hf refining. IntroductionElectron beam melting and refining (EBMR) is a method applied in the special electrometallurgy for production of pure metals and alloys and of new materials [1][2][3][4][5][6]. The electron beam technologies and, in particular, the technologies for EBMR of metals and alloys have been recognized as a competitive, if not the only, method for obtaining new materials for uses in various fields: nuclear industry, medicine, electronics, instrument engineering, transport, etc. The principle and a description of the EBMR process have been presented in [1,2,3,6]. Computational modeling gives a possibility for a better understanding and investigating the heat transfer mechanisms and can be used for optimizing the electron beam process for obtaining new materials with improved characteristics. In [7], a stationary heat model was described and applied to studying the EBMR process. This mathematical model was extended to a time-dependent heat model with a Pismen-Rekford numerical scheme that is absolutely stable with respect to the time [8].

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