1967 Volume 53 Issue 14 Pages 1569-1585
Single- and complex-deoxidations with Mn, Si, and Al are practised in steel baths melted by highfrequency induction furnace and Tammann-oven, respectively. Deoxidation-process are analysed on the stand point of kinetics with an eye to quantitative measurement of the separation-rate of primary inclusion. The results of experiments and evaluation are summarized as follows:
(1) Deoxidation-process in transient time just after the addition of deoxidizers is different from that during the stationary time after the transient time.
(2) In transient time just after the addition of deoxidizers they are in course of reaction with oxygen in iron, and produced inclusions have the tendency to coagulate because of (FeO) or (MnO) in the presence of Mn, in inclusions as a component, whose rapid separation brings about deoxidation of steel.
(3) After the transient time deoxidation-product separates from bath in course of time according to the mathematical form C=Co exp (-kt)(t: time) in the stirred bath.
(4) As the separation-rate coefficients k differ in different kinds of crucibles, rate-determing step of separation of primary inclusion in stirred bath is chemical reaction between crucible materials and deoxidation-products.
(5) Contrary to stirred bath separation-rate of primary inclusion in tranquil steel bath is confirmed to follow the theoretical equation which is introduced for the first time, assuming the validity of Stokes' law.
(6) The above theoretical equation can well explain the separation-rate of inclusion in tranquil steel bath when the mathematical distribution form of inclusion radius, which follows N=A exp (-Ar)(γ: Radius of primary inclusion particles) and bath height are given.
(7) Separation of inclusion in tranquil steel bath as in ladle would be promoted by stirring the steel bath.