EFFECT OF THERMAL BARRIER COATINGS ABOVE MOULD MENISCUS ON MOULD HEAT TRANSFER AND OSCILLATION MARK MORPHOLOGY OF STRANDS

Oscillation marks are closely related to the surface quality of bloom. Excellent surface quality of bloom is essential assurance of the technology of continuous casting and rolling. The improvement of heat transfer process through mold is beneficial to alleviate oscillation marks. A new method of inhibiting formation of oscillation marks in continuous casting, namely spraying or embedding thermal barrier coatings above mold meniscus (TBCMM) was proposed, by which the temperature and heat flux fluctuation of meniscus was reduced, and then the surface quality of strands was improved. Using an one-dimensional heat transfer sinmlating apparatus, the effect of location of thermal barrier coatings on heat transfer near meniscus was investigated, and the possible mechanism of TBCMM on inhibiting formation of oscillation marks was also discussed. With a dip simulator for continuous casting, lower melt point Sn-12.5%Pb alloy was casted with thermal barrier coating (TBC) and without TBC molds respectively, and the temperature fluctuation was also measured. The heat flux near meniscus in mold and the oscillation marks morphology on strands confirm the effectiveness of the proposed TBCMM. Finally, in a pilot continuous caster, casting experiments of steel with TBCMM was conducted, and the oscillation marks on billet surface were alleviated or removed.