Experimental Study and Modeling of the Precipitation of Non-metallic Inclusions during Solidification of Steel

An original model for the calculation of the precipitation of non-metallic inclusions during solidification has been developed at IRSID. The microsegregation equations and the equilibrium conditions between liquid steel and oxide, sulphide, nitride, carbide inclusions are combined in a general multiphase equilibrium code. Sulphide precipitation in several steel grades: plate grades, medium carbon and bearing steels has been analyzed in laboratory samples quenched from a partially solidified state. For the various steel grades investigated, the computed results of sulphides (Mn, Fe)S or (Mn, Fe, Cr)S compositions are in good agreement with the results of the experimental study. Another example concerns the precipitaion of oxide inclusions in semi-killed high-carbon steels: The calculation represents very precisely the observed heterogeneous population of oxide inclusions formed at different stages of the industrial process.