Effects of time, temperature, and steel composition on growth inclusions in liquid and dissolution of steels

The current knowledge of stability and growth dissolution kinetics of inclusions in liquid steels is synthesised to understand their growth and dissolution behaviour. In particular, it is shown that the effects of time and temperature on the diffusion controlled growth and dissolution behaviour of inclusions can be represented by a set of time-temperature-transformation (TTT) diagrams. The TTT diagrams for the growth of oxide, nitride, and sulphide inclusions show the characteristic C shape, with each plot having an optimal temperature where the highest growth rate is achieved. The inclusion dissolution rate depends strongly on the initial inclusion radius and temperature. Apart from the stability of various inclusions in a given composition of steel, the diagrams provide important kinetic information for diffusion controlled growth and dissolution of oxide, nitride, and sulphide inclusions.