A Study for Initial Solidification of Sn-Pb Alloy during Continuous Casting: Part I. The Development of the Technique

The importance of initial solidification of molten steel in the mold has been widely acknowledged. However, very few studies have been effectively developed because of the high transient nature of thermodynamics and fluid flow in the upper mold. Based on the recently developed mold simulator technology, a novel technique has been successfully developed to study the initial solidification behavior of Sn-Pb alloy, which gives rise to the clear understanding of the interrelationship between complex meniscus heat transfer, casting surface oscillation marks (OM), and mold hot-surface responding temperatures. The results suggested that the variations of the responding temperatures and heat flux at meniscus may be associated with the movement of mold in/out of the bath, the infiltration of silicon oil, and the latent heat release due to the solidification of meniscus during negative strip time (NST). The presence of positive peaks in the derivative of the heat flux are corresponding to each of the OM during NST, which suggests the significant increase of heat flux during the formation of OM. These could be explained as the meniscus is deformed and gets closer to the coldest mold at the beginning of NST, such that the liquid meniscus that gives rise to the increase of heat flux would be solidified. With the enhancement of oil infiltration from the mid-NST to end-NST, the thermal resistance between the solidified meniscus and mold decreases; therefore, the shell continues to grow, and the resulting heat-transfer and mold temperatures also continue to increase.