Study On Inclusions Control Of IF Steel For Auto Application

IF steel has advanced deep draw behavior and no aging effect,it has became the third generation of stamping steel followed rimming steel and low carbon Al-killed steels. It has super high stamping performance, which is a symbol of a country's auto plate production level. During steel making process,inclusions control level has the decisive function to auto plate quality.Through the researches of industry test,some laws were found in the process of BOF,RH,CC as to inclusion change. We can draw a conclusion that there are four types of inclusion in IF steel's slab, which are the cluster inclusions of A1₂O₃ system, block inclusions of A1₂O₃ system, inclusions of A1₂O₃-CaO or A1₂O₃-CaO-SiO₂ system, and inclusions of A1₂O₃-Ti2O3 system. Block inclusions of A1₂O₃ system and inclusions of A1₂O₃-CaO-Si O 2 system are the main factors causing the surface defects of IF steel's slab. So we take some measures to control the inclusions of IF steel for auto application, which are as follows, reducing the slag entrainment in convertor, keeping the [O] activity value at a certain range after de-carbon in RH process, avoiding the temperature increasing during the RH treatment, decreasing the oxidation ability of top slag in the ladle and the re-pollution of steels during the continuous casting, decreasing the amount of cluster inclusions which can deteriorate the surface quality of products seriously, stabilizing the processes,etc..