Physical Modeling Of Slag/Steel Interfacial Behavior In Slab Continuous Casting Mold With Argon Blowing

The continuous casting mold is playing an important role in the improvement of the quality of cast slabs since it is the final stage for inclusions control during continuous casting process. So it is necessary to understand the effect of bubbles on behavior of molten steel and slag in mold, that it will be of significance in both theory and practice to improve the strand quality and the performance of continuous casting process.Based on the similarity principles and the operating condition for a slab continuous casting machine in some steelworks, a water modeling system for mold with the size ratio 1:2.5 was established. The DJ800 was used to measure the mold surface fluctuation with argon blowing, the process of interfacial movement and slag entrapment were recorded by camera. Meanwhile, the effects of operating parameters on transport phenomena in mold were investigated. The main results obtained are as follows:(1) For the mold section size of 2200mm×280mm(sectionⅠ)with the operating condition as 15°of nozzle,140mm of immersion depth,4L/min of argon blowing, the surface fluctuation will increase firstly, then decrease as casting speed increases from 0.85m/min to 1.15m/min, and the maximum of surface fluctuation is 3.3m/min when the casting speed reaches 1.0m/min. For the mold section size 1500mm×280mm(sectionⅡ), the surface fluctuation will decrease firstly, then increase as the casting speed increases from 1.Om/min to 1.3m/min, and the minimum for surface fluctuation is 1.8mm as the casting speed is 1.1m/min.(2) For the mold sectionⅠ, with the operating conditions as 0.85m/min of casting speed, 140mm of immerging depth,4L/min of argon blowing, the surface fluctuation will decrease firstly then increase, and the minimum is 1.43mm when the angle of nozzle is 12.5°as the angle of nozzles increase from 10°to 17.5°. For the mold sectionⅡ, at the casting speed of 1.0m/min, the surface fluctuation increase firstly then decrease, and the maximum is 2.06mm when the angle of nozzle is 15°.(3) For the mold sectionⅠ, with the operating conditions as 0.85m/min of casting speed, 15°of nozzle,4L/min of argon blowing, the surface fluctuation decrease firstly then increase when immersion depth increase from 110mm to 170mm, and the minimum is 1.59mm when the immersion depth is 140mm. For the mold sectionⅡ, as the casting speed is 1.0m/min, the surface fluctuation increase firstly, and then decrease, and the maximum is 2.06mm when the immersion depth is 140mm. With the comprehensive consideration of the effect of immersion on surface fluctuation and slag entrapment, the optional immersion depth for nozzle is 140mm-170mm.(4) The effect of argon flow rate on the average wave height is not so great, but the variation of the argon flow rate affects the surface fluctuation greatly on some local area, which affects the powder entrapment. With the present experimental conditions, the reasonable argon flow rate is (2-4)L/min to avoid the powder entrapment.(5) For the mold sectionⅠ, the surface fluctuation in upper backflow area is the main factor affecting the surface fluctuation. For the section mold sectionⅡ, many of the ascending bubbles are the main reason affecting the surface fluctuation.(6) For the molds with wide of 1500mm,1800mm,2000mm and 2200mm, there is no powder entrapment by shear force or vortex, and powder entrapment caused by shear force appears only when the steel flow rate exceeds 51.744m3/h.(7) The effect of gas flow rate is not important to the mode of powder entrapment, but it is more closely related to the steel flow rate. When the steel flow rate is less than 33.6m3/h, powder entrapment by attacking of bubbles stream will occur easily; and when the steel rate is more than 30.24 m3/h, powder entrapment similar to vortex will frequently appear; when the steel flow rate is between them, both modes of powder entrapment may occur.