Physical simulation of slag entrapment behavior in funnel-type mold of thin slab continuous casting
LIU Peng1,2, ZHENG Wan1,2, WANG Jun-chi2, WANG Chun-feng3, GAO Yun-ming1,2, YE Fei3
1. The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China; 2. Hubei Provincial Key Laboratory for New Process of Ironmaking and Steelmaking, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China; 3. CSP Hot Rolling Sheet Plant, Baosteel Wuhan Iron and Steel Co., Ltd., Wuhan 430083, Hubei, China
Abstract:Aiming to solve the problem of slag entrapment in thin slab continuous casting mold under high casting speed process, the effects of casting speed, nozzle insertion depth and mold flux viscosity on the change of liquid slag layer and slag entrapment behavior in funnel-type mold were studied by a 1∶1 hydraulic model and using water/vacuum pump oil to simulate steel/mold flux medium. The results show that with the increase of casting speed, the wave height of liquid level in the mold rises, the liquid level height gradually decreases from the narrow side of the mold to nozzle, and the thickness of liquid slag layer changes from thin to thick correspondingly, which leads the molten steel near the narrow side of mold to expose. The wave height at 1/2 between the narrow side of mold and the nozzle varies greatly, and the liquid velocity is the largest, which has contributed to shear slag entrapment. Under the experiment conditions, the measures such as increasing the nozzle insertion depth, reducing the maximum casting speed and properly increasing the viscosity of mold flux, can prevent the occurrence of shear slag entrapment in the mold by controlling the liquid level velocity to be less than 0.486 m/s and the liquid level fluctuation index F value to be less than 5.45. However, these means can not avoid the occurrence of vortex slag entrapment near the nozzle in the mold because the flux of thin slab continuous casting steel is large and the funnel-type mold and duckbill shaped nozzle are easy to form negative pressure vortices.
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