The Microstructure Formation in Slag Solidification at Continuous Casting Mold

The microstructure of slag film solidified on the inner wall of mold in continuous casting of low carbon steel has been examined experimentally and analyzed theoretically. A puzzle for the crystallization sequence has been solved by this work, which is useful to guide the modification of slag microstructure in efficient casting of advanced steels. The experiments observed three crystalline bands, each containing an initial block-shaped crystal sub-band and late-developed dendrite sub-band. The grain size and morphology change monotonically across the crystalline layers to form a gradient structure. The reason for this is that the solute segregation causes considerable surging of viscosity and constitutional undercooling in the liquid phase. This is rarely seen in the casting of alloys and have not been pointed out previously in the casting of oxide mixtures.

Automated summary

The microstructure of slag film solidified on the inner wall of mold in continuous casting of low carbon steel has been experimentally examined and theoretically analyzed. This work has solved a puzzle for the crystallization sequence and is useful for guiding the modification of slag microstructure in efficient casting of advanced steels. Three crystalline bands, each containing an initial block-shaped crystal sub-band and late-developed dendrite sub-band, were observed in the experiments. The grain size and morphology change monotonically across the crystalline layers to form a gradient structure, due to solute segregation causing an increase in viscosity and constitutional undercooling in the liquid phase. This phenomenon is rarely seen in alloy casting and has not been pointed out previously in the casting of oxide mixtures.