Effect of Electromagnetic Stirring Position on Uniform Direct Chill Casting of Large-Sized 7005 Alloy Billet
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https://doi.org/10.1007/s11837-020-04362-7 Ó 2020 The Minerals, Metals & Materials Society
SOLIDIFICATION BEHAVIOR IN THE PRESENCE OF EXTERNAL FIELDS
Effect of Electromagnetic Stirring Position on Uniform Direct Chill Casting of Large-Sized 7005 Alloy Billet YAJUN LUO ,1,2,5 ZHENGGANG WU,2 LI ZHOU,1 MIN HE,3 ZHENLIN ZHANG,3 XIAOMIN PENG,1 and ZHIFENG ZHANG4 1.—Hunan Provincial Key Laboratory of Vehicle Power and Transmission System, Hunan Institute of Engineering, Xiangtan 411104, China. 2.—College of Materials Science and Engineering, Hunan University, Changsha 410082, China. 3.—Hunan Wenchang New Material Technology Co. Ltd, Loudi 41700, China. 4.—General Research Institute for Nonferrous Metals, Beijing 100088, China. 5.—e-mail: [email protected]
A numerical simulation is carried out to investigate the effect of the stirring position on large-sized 7005 alloy billet prepared by direct chill casting imposed with A-EMS and intercooling named uniform direct chill (UDC) casting. Moreover, the effect of the stirring position on the Lorentz force, fluid flow, heat transfer, and solidification occurring in UDC casting is investigated. It is found that when the stirring position moves upwards, the Lorentz force imparts the forced flow to the melt more effectively. Moreover, when the stirring position increases from 0 mm to 100 mm with respect to the graphite ring level, the maximum convection velocity of the melt increases from 150 mm/s to 210 mm/s. Furthermore, the temperature field of the melt in the sump becomes more homogeneous as the stirring position elevates. The microstructure of the 7005 billets becomes finer and uniform when the stirring position moves up to 50 mm.
INTRODUCTION Electromagnetic stirring (EMS) plays an important role in the solidification of metals, especially in direct chill (DC) casting, to prepare high-quality aluminum alloy billets for manufacturing large parts in diverse industries, including aerospace, rail transportation, shipbuilding, and other hightechnology applications. Recently, many researchers have focused on optimizing the stirring condition of the EMS for solidifying microstructures.1–3 Reviewing the literature shows that numerous experimental and numerical investigations have been carried out so far for studying the EMS and the corresponding process parameters. Wang et al.4 experimentally investigated the effect of different values of the EMS alternating current on the microstructure of the Incoloy 825 superalloy. They showed that as the EMS alternating current (Received May 7, 2020; accepted August 26, 2020)
increases, the equiaxed grain zone expands and the columnar grain zone shrinks. Chen et al.5 found that as the applied voltage and rotational frequency increases, the average grain size and shape factor of Mg-Nd-Zn-(Zr) alloy initially decrease and then increase. Moreover, studies show that high-quality billets can be obtained by optimizing EMS parameters.6,7 However, as the billet size increases, the skin effect can significantly reduce the stirring effect of the e
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