Basic Research And Multidimensional Evaluation On The Crystallization Behavior Of Mold Flux During Continuous Casting

The crystallization properties of mold flux are not valued by factories, which leads to a series of problems about slab surface defects. Therefore, the influence of, Ti O2, basicity and Ca F2 on crystallization behavior of mold flux is studied with single factor method, by the use of SHTT II, XRD and metallurgical microscope. Change laws of cooling rate of flux film at the slab side are obtained with the mold flux film temperature field and the MATLAB. The following main conclusions are that:1) When 2.01%<Ti O2<15.01%, Ti O2 first inhibits and then promotes crystallization of mold flux. crystallization temperature and crystallization activation energy first increases and then decreases with the increase of Ti O2 content. Crystallization phase composition is to inhibit precipitation of cuspidine perovskite and then promote the precipitation of cuspidine under the condition of precipitation of perovskite.2) The increase of Ca F2 and basicity promote devitrification. Devitrification temperature and devitrification activation energy decrease with the increase of basicity and crystallization phase changes from cuspidine to gehlenite. The flux film surface begins to appear bulges、pits and a mass of internal defects with the increase of annealing temperature of flux film. Crystallization temperature and crystallization activation energy decrease with the increase of Ca F2 and temperature range of the presence of liquid phase gradually becomes longer.3) The temperature field, cooling rate model are simulated with ANSYS and MATLAB. Cooling rate of flux film along the direction of the mold is obtained.4) Design principles of mold flux with high casting speed and low carbon and higher crystallization temperature is to increase the incubation time and reduce the critical cooling rate. The phenomenon of peritectic steel with casting pit, meat, vibration mark disorders and distortion and high carbon steel with surface crack in the edge and corner is analyzed. Mold flux crystallization should be strictly controlled and mold flux with devitrification temperature should be used. Otherwise, quality problem will appear.