Shear Thinning Behavior and Surface Properties of Mold Flux for Thin Thickness Slabs at High-casting Speed

Abstract

In this paper， a steel plant with high pulling speed thin thickness slab continuous casting process as the object is studied， the specific process parameters of the pulling speed of 5.5 m/min， pouring temperature of 1 544 ℃， crystallizer water pressure of 15.6 Pa， the cooling water temperature of 39.1 ℃， and the inverted taper of the crystallizer 7.5 mm and so on.In the process of on-site continuous casting， it was found that the risk of slag rolling increased and the casting bond alarm occurred frequently， the conventional slags and non-Newtonian fluid mold flux with only shear-thinning properties could not effectively in solving these problems .With the mold flux of medium carbon steel on-site as the original mold flux ， combined with additives such as MgO and SiC ， a new type of protective slag with strong shear-thinning properties and high surface tension is prepared. The shear thinning properties， surface properties and microstructure of mold flux were detected and studied by rotating cylinder method and other methods. The results show that with the increase of SiC content， the shear thinning property， contact angle， surface tension and interface tension of the mold flux all show the trend of increasing first and then decreasing， the content of C-O bond and C-Si bond increases， and the degree of molecular polymerization increases . When the SiC content is 0.98%， the shear thinning property is the strongest， and the contact angle， surface tension and interfacial tension are the largest. This enables the mold flux to meet the viscosity requirements at different shear rates， thus effectively suppressing the crystallizer slag rolling behavior and reducing the risk of bond leakage.

Keywords

• mold flux； shear thinning； sessile drop method； surface tension； microstructure