The Design Of RH Refining Slag Of Automotive Deep-Drawing Steel

The IF steel with high strength and good deep drawing property is mainly used inthe production of automobile deep drawing parts. The cold rolled plate is mainly used tomanufacture the good qualified steel plate, like the automobile panels and so on. Theindustrial production of IF steel in China has reached a certain stage in scale, still there isa gap between China and the foreign counties on the quality of the steel used for theproduction of the high-level automobile panels. Aiming at nozzle nodulation and lowsequence casting samples of IF steel during BOF�'RH�'CC producing process，thereserch of Al₂O₃absorbing ability of RH refining slag will be started。Through studying on CaO-Al₂O₃-SiO₂Ternary Phase Diagram, finding that slagsuitable for RH refining slag of IF steel，which is composed of CaO=40%～52%、Al₂O₃=25%～38%、SiO₂=6%～12%，main phases is12CaO·7Al₂O₃、3CaO·Al₂O₃and2CaO·Al₂O₃·SiO₂，helping to improve the melting slag’s Melting properties andfluidity；Using coexist theoretical analysis thermodynamic conditions of RH refiningslag, established CaO-Al₂O₃-SiO₂-MgO-FeO-CaF₂-MnO slag system prediction modelwhich can predict the different components of the RH refining slag Al₂O₃absorptionability.The CaO/Al₂O₃of Refining slags impact on the ability to absorbing Al₂O₃has ahigh absorption rate about1.7, Al₂O₃absorption rate increases with the increase of CaF₂content of the refining slag; the final design of the refining slag Composition the basicityis3.27, CaO/Al₂O₃is1.43, FeO+MnO content is7%.Through the analysis of slag andsteel in the Process of IF steel in RH refining, it is found that, at the end of RH refining,T[O] of liquid steel at92ppm, microscopic inclusions mainly is Al₂O₃-based, includingAl₂O₃-TO₂、TiN、MgO·Al₂O₃, quantity of inclusions at about6.21/mm², the size of thevast majority of inclusions is less than5μm.The designed refining slag is conducive tothe removal of Al₂O₃inclusions in the liquid steel.