Behavior of Non-metallic Inclusions and Bubbles in Front of Solidifying Interface of Liquid Iron

Abstract

The velocity of small particle caused by interfacial tension gradient in the boundary layer of concentration formed in front of an advancing solid-liquid interface is derived as follows:
V₁ = (4/9ηD_L) (1-K_E) Co (dσ/dC_L)RV_S × [1+ (9/8)R/ (x-R)]^-1exp[-V_s (x-δ)/D_L]
Using the equation, the behavior of Al₂O₃ inclusions and bubbles in the boundary layer of concentration of Fe-O, Fe-Ti, Fe-S systems was analysed and clarified in relation to solidifying velocity, bulk flow of the liquid iron and solute concentration as well as radius of inclusion or bubble. The analyses predict that the small Al₂O₃ inclusions or bubbles move toward and contact solidifying interface due to the concentration gradient of the solute O, Ti, S and the velocity of the inclusions and bubbles increases with increase of the concentration of the solutes O, Ti and S.