Effect of Ar Bubbling on Removal Rate of Alumina Inclusion in Al Deoxidized Steel

Abstract

Effect of Ar bubbling on the deoxidation rate of molten steel with Al has been investigated in 20 kg scale induction furnace. The results are summarized as :
(1) The deoxidation was completed within 5 to 15 min depending on experimental conditions. The final total oxygen content was 30 to 45 ppm.
(2) The deoxidation model has been proposed in which deoxidation rate should be determined by the balance of removal and reentrainment rates of alumina inclusion.
(3) The removal rate constant was obtained at each condition. The apparent activation energy was obtained as 284, 355, 368 kJ/mol, respectively with Ar flow rate of 0, 5, 10 l(STP)/min.
(4) The removal rate constant was expressed as a function of total stirring energy density for induction stirring(ε_ind)and Ar gas stirring(ε_B/B), namely, k=k₁(ε_ind+ε_B/B)ⁿ.The value of n was obtained as 0.50 to 0.65.
(5) The contribution of entrapment of inclusion in bubbles was estimated quantitatively. The transfer coefficient of inclusion migration to bubble was also estimated.