An Online Contactless Investigation of the Meniscus Velocity in a Continuous Casting Mold Using Lorentz Force Velocimetr
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ODUCTION
CONTINUOUS casting is the most important casting process in the metallurgical industry. In 2016, 96 pct of the steel in the world was produced by continuous casting.[1] During the continuous casting of steel process, the primary melt is delivered to the tundish and then flows into the mold through the submerged entry nozzle (SEN).[2,3] The mold is usually considered to be the heart of a continuous mold (as shown in Figure 1) and is a complex system consisting of molten steel flow, mold flux, shell, and copper wall.[4–6] The main function of the mold is transferring the heat of molten steel to the cooling system mounted in the copper wall such that the molten steel solidifies evenly in the course of its vibration into a slab of specified shape with a liquid core.
JINCAN ZHENG, RUNCONG LIU, and XIAODONG WANG are with the Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, P.R. China. Contact e-mails: [email protected], [email protected] GUODONG XU is with the Steelmaking Plant, Baoshan Iron Steel Research Institute, Beijing 100081, P.R. China. Manuscript submitted May 20, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS B
The surface velocity of molten steel flow in the mold is closely related to the quality of the product[7–9]: excessive flow rate will aggravate the unsteady flow of molten steel, such that shear flow will occur at the interface between molten steel and slag, resulting in slag entrainment; too low flow rate will lead to super-cooling of molten steel near the surface area, which may cause hook formation, non-uniform slag consumption, inclusion particles, or bubbles, leading to various surface defects.[10–12] Hence, real-time monitoring and control of the surface velocity of molten steel flow in the mold[12] is required for the continuous casting process. Many methods have been explored in the laboratory and industrial practice[13] to measure the velocity of liquid metal at high temperature, such as a hot-film anemometer, contacting probes of all sorts (reaction probe, melting probe,[14] Vive`s probe, Karman vortex probe,[13,15] and the nail-board approach[10,12,16–18]), and ultrasonic Doppler velocimetry. The hot-film anemometer is based on the fact that the heat transferred from a film is directly related to the flow velocity approaching it. The principle of the contact probe is to obtain the flow velocity of molten steel by the geometric parameters of a probe immersed in molten metal, the characteristics of the lump of the probe after molten metal, or the electrical signal or disturbance characteristics formed by the probe immersed in molten steel. Ultrasound Doppler velocimetry is based on the Doppler effect of a sound wave propagating in flowing molten
of molten steel, together with the structure of the LFV device, is given in Section II. Calibration in the laboratory (Section III), followed by in-plant tests (Section IV), are carried out with our LFV device. Quantit
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