| It is a crucial issue to be resolved in the slab casting that how to adjust the ratiobetween glass phase and crystalline phase of the slag film, and coordinate contradictionbetween heat transfer and lubrication. What’s more, the study of mineral composition oncrystallization properties for casting mold powder has not been concluded yet. Therefore,the influence of mineral composition on crystalline behavior of mold fluxes has beenfocused on by the application of SHTT, and the effect of mineral composition on the slagfilm structure has been studied by the Heat Flux Simulator Equipment of mold slag films.The conclusions can lay theoretical foundation for the quantitative control of mineralcomposition and film structure, which is to coordinate heat transfer and lubrication.The influence rules of the mineral content on maximum cooling rate, crystallizationtemperature and crystallization rate have been studyed by constructing CCT, TTT curvesof mold fluxes. With the mineral content of quartz, wollastonite, soda ash increasing, themaximum cooling rate decreases, and the crystallization temperature under the samecooling rate decreases, which indicate crystallization of mold fluxes weakening. Quartz,wollastonite of mold powder can retard crystallization rate, while the influence of sodaash is opposite. In light of the impact on crystallization of slag films, the ability of quartzis slightly stronger than wollastonite, soda ash. With the content of fluorite increasing, themaximum cooling rate, the crystallization rate and the crystallization temperature underthe same cooling rate all increase, indicating fluorite can promote the crystallization.The effect of mineral composition on the crystallization mineral and crystallizationratio has been studied by the Heat Flux Simulator Equipment of mold slag films. With thecontent of quartz, wollastonite increasing, the wollastonite in slag film can be promoted,and the cuspidine can be restrained. But the content of fluorite, soda increasing, promotecuspidine in slag film crystallization, and inhibite wollastonite generation. Moreover,fluorite can increase the crystallization ratio, but the effect of soda is opposite. The resultsalso show crystallization properties change obviously, when the mineral content reach22%of quartz,17%of wollastonite,14%of fluorite and16%of soda ash.The industrial mold fluxes and slag films for Q235B and Q345B slab casting havebeen studied to find out the relationship between steel style, casting process and moldfluxes. And then, regarding the four properties requirements as the optimization goals,the optimum mineral compositions suitable for different kinds of steel have been elected.The influence rules of the mold powders and slag films got from the laboratory, are inwell agreement with the optimization design of mold powders. The results can provide atheoretical basis for reasonable material choice to develop high-quality powders. |
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