Research On Mold Flux For High Strength Ship Plate Steel Continuous Casting

With the development of the shipbuilding industry, the higher requirement forthe quality of the ship plate steel was put forward. It is easy to form the crack incasting ship plate steel, and mold flux is important auxiliary material in thecontinuous casting process. The influence of performance on quality of ship platesteel and carrying on continuous casting smoothly is important.According to analysis of mold flux in practice, the high strength ship plate steelmold flux was compounded in laboratory. The effects of additive of Li₂CO₃, Na₂CO₃,NaF and B₂O₃on melting temperature, viscosity and A1₂O₃inclusions absorptionwere researched. The design principle of high strength shipbuilding steel mold fluxwas discussed. The results were shown as follows. The Li₂CO₃was added in anamount of1%to3%, the Na₂CO₃was added in an amount of1%to9%and the NaFwas added from2%to10%, which can effectively improve the melting temperature,viscosity and inclusion absorption ability of mold flux. B₂O₃was added in an amountof1%to5%, it can effectively improve melting temperature, viscosity of mold flux,and absorption of A1₂O₃inclusion had no significant effect.The melting, crystallization and consumption of mold flux that used for highstrength ship plate steel continuous casting were analyzed. The results were shown asfollows. The mold flux generated volatiles like bubbles during the melting process. Itmay be the gas and the oxidation of organic matter from mold flux under hightemperature. Mold flux had shrinkage during crystallization, and the crystallinemineral phases were mainly cuspidine （Ca₄Si₂O₇F₂） and akermanite （Ca₂MgSi₂O₇）.The flowing length of mold flux was0.76cm/g, and it closed to that of mold fluxin practice. The mold flux could meet the needs in practice, and replaced the actualmold flux. It will help to improve the quality of slab.