Solidification Behavior in the Presence of External Fields: Part II
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https://doi.org/10.1007/s11837-020-04384-1 Ó 2020 The Minerals, Metals & Materials Society
SOLIDIFICATION BEHAVIOR IN THE PRESENCE OF EXTERNAL FIELDS
Solidification Behavior in the Presence of External Fields: Part II ANDREW KAO
1,3
and LANG YUAN2,4
1.—School of Computing and Mathematical Sciences, University of Greenwich, London SE10 9LS, UK. 2.—College of Engineering and Computing, University of South Carolina, Columbia, SC 29201, USA. 3.—e-mail: [email protected]. 4.—e-mail: [email protected]
The introduction of external fields, such as electromagnetic fields, ultrasonic excitation, and mechanical shearing, to solidification processes has encompassed novel applications to refine grains, homogenize segregation, break up agglomeration of particles, and prevent defect formation. Advances in experimental methods, materials characterization, and computational modeling have led to new insights into controlling microstructure and defects during solidification. This two-part topic ‘‘Solidification Behavior in the Presence of External Fields’’ highlights most recent investigations into the use of external fields in a broad range of industrial manufacturing processes. The second part includes the use of ultrasonic treatment, high-shear processing, electromagnetic levitation, and pulsed electric currents. Ultrasonic treatment (UST) in alloy processing is an emerging technology that has been shown to produce grain refinement and degassing. Typically, UST has been studied under batch conditions and treating a single volume of fluid; here, two papers are presented that investigate extending these findings to continuous processes in direct chill (DC) casting. The paper by Subroto et al, titled ‘‘Structure Refinement upon Ultrasonic Melt Treatment in a DC-Casting Launder,’’ describes an experimental and numerical study of UST in a pilot-scale DC casting launder. Their findings show that by controlling the fluid flow conditions the residence time can be increased, leading to increased grain refinement and degassing. This is a promising first step to upscaling UST to industrial-scale applications.
Lang Yuan and Andrew Kao are guest editors for the Solidification Committee of TMS and coordinated the topic Solidification Behavior in the Presence of External Fields in this issue. (Received September 2, 2020; accepted September 9, 2020)
The second ultrasonics paper on DC casting by Tonry et al., and titled ‘‘Contactless Ultrasonic Treatment in Direct Chill Casting,’’ concerns the use of a contactless sonotrode in UST as a continuous process through a detailed numerical study coupling electromagnetism, ultrasonics, heat transfer, fluid flow, and solidification. A key finding is that the system tends to a single stable resonant mode in the melt pool with increasing length of the billet. This could allow for a single driving frequency to be used throughout the entire process. High-shear melt conditioning (HSMC) technology is a process that draws the melt into a high-speed rotor–stator mixer. An intense shearing field is ge
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