Mathematical Modeling of Heat Transfer and Deformation of Bloom Tube Mold in Continuous Casting Process

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IN a continuous casting process, cooling water comes into direct contact with the entire cold face of the tube mold, which is formed by a single piece of copper. In contrast to the combined molds, the tube molds are fabricated without a gap (~ 0.3 mm) between the copper plates, and the water slot at the corner is more reasonable. The cooling effect of the tube molds is more uniform than that of the combined molds, thereby resulting in better quality steel slabs. However, the thickness of the copper plate for the tube molds is ~ 30 mm; hence, installation of the thermocouples for monitoring the temperature variation during continuous casting is difficult. In addition, the copper tube is simply fixed with water jackets at the top and bottom. The copper tube is therefore prone to deformation, and the deformations on the wide and narrow sides affect each

JIANHUA ZENG is with the College of Materials Science and Engineering, and Chongqing Key Laboratory of Vanadium?Titanium Metallurgy and Advanced Materials, Chongqing University, Chongqing 400044, China and also with the Pangang Group Research Institute Co., Ltd., Panzhihua 617000, Sichuan, China. MEIJUAN GAN, XIAOBO YAN, QIANGQIANG WANG, and SHENGPING HE, are with the College of Materials Science and Engineering, and Chongqing Key Laboratory of Vanadium?Titanium Metallurgy and Advanced Materials, Chongqing University. Contact e-mail: [email protected] Manuscript submitted June 5, 2019.

METALLURGICAL AND MATERIALS TRANSACTIONS B

other, leading to complex deformation. Sufficiently high levels of deformation result in uneven cooling and affect the quality of the casting billet. The deformation of the copper mold is a result of the interaction between thermal and restraining forces.[1] Until now, several deformation mechanisms have been proposed, namely, plastic deformation, thermo-elastic distortion due to the temperature gradient within the copper wall, and the abrasion wear. Table I summarizes studies on mold distortion of the continuous casting process. [1–8] Simulation studies of a mold copper temperature field have generally ignored the influence of liquid steel flow behavior,[8] directly loaded hot face temperature, and the heat transfer coefficient or heat flux.[4,9,10] Therefore, inaccurate values were obtained for the copper temperature difference under different continuous casting parameters, especially at the copper corner. The convection heat transfer was loaded at the water wall (cold face).[4,8,11,12] Furthermore, the cooling water temperature in the height direction was considered to be either constant[3] or increasing linearly from the inlet to the outlet.[12] These assumptions differed considerably, however, from the actual scenario. Chen et al.[13,14] considered the cooling water flow behavior and established a model accounting for the fluid flow, heat transfer, and solidification of liquid steel. This model yielded the water temperature distribution and heat transfer behavior and predicted the heat transfer characteristics of the copper plate under different mold corner