In order to study the evolution of inclusions in the ultra-high strength steel production process and the level of cleanliness control,the smelting process samples were analyzed by scanning electron microscopy and large sample elec-trolysis,and the best low melting point area of the refined slag system was calculated with the help of Factsage software.The results indicate that the inclusions in the steel during RH void breaking are mainly composed of calcium aluminate salts.With the increase of soft blowing time,calcium aluminate inclusions continuously transform into CaS inclusions.The compo-sition of refining slag deviates from the low melting point area of SiO2-CaO-MgO-Al2O3 quaternary phase diagram,and the poor fluidity of top slag leads to weak ability to adsorb inclusions.Therefore,by analyzing the influence of MgO mass frac-tion,basicity and calcium-aluminum ratio on the low melting point area,the basicity of refined slag is adjusted to be between 5 and 9,Al2O3 mass fraction is adjusted to be between 25%and 35%,and MgO mass fraction is adjusted to be between 4%and 6%.After optimization,the total amount of the billet inclusion was reduced from 1.78 mg/10 kg to 0.90 mg/10 kg,and the degradation rate of the finished product was reduced from 0.42%to 0.12%due to the inclusion defects.
NETL
NSTL
维普
万方数据
