Mechanism of Deoxidation with Silicon in Inductively Stirred Liquid Steel

Abstract

The rate of deoxidation with silicon and silicon-calcium alloys in inductively stirred liquid iron was studied to make clear the mechanism of deoxidation in such stirred system. Some proposed models were discussed to explain the behaviour of small particles formed by deoxidation. The results obtained are summarized as follows: 1. The process of deoxidation by the addition of deoxidation elements consists of the three stages of incubation period, rapid-decreasing period, and slow-decreasing period. 2. The number of particles and size of deoxidation products are governed by the supersaturation at a moment of addition. The number of particles increases and particles diameter decreases with increasing supersaturation in the melt. 3. The growth of the particles takes place on two steps, that is, very rapid growth at a moment of addition and slow growth subsequently to the formation of small particles. The former is controlled by the diffusion of the solute to the nuclei of deoxidation products, and the latter is proceeded by the collision of particles due to velocity gradients in turbulent flow. 4. The particles in stirred melts are removed by the collisions of particles on the crucible walls. 5. The rate of deoxidation with silicon-calcium alloys is rather slow compared with deoxidation by silicon due to the formation of very fine particles as the deoxidation products.