Evolution Mechanism of Inclusions in H13 Steel with Rare Earth Magnesium Alloy Addition

Abstract

Rare earth metals have strong affinity with O and S in molten steel. However, due to high density of rare earth inclusions close to that of molten steel, rare earth inclusions are not easy to float up and it is not conducive to take away O and S. In this paper, the influence of rare earth magnesium alloy on the evolution mechanism of inclusions and deoxidization and desulfurization in H13 steel was analyzed, and the thermodynamic calculation was developed. The research results indicate that the composite inclusions of low-density MgO attaching or wrapping on the surface of high-density Ce inclusions are formed after adding Ce–Mg alloy to H13 steel. Compared to Ce inclusions alone, composite inclusions have lower average density and larger diameter, so that they have a faster floating rate according to Stokes law and are easier to float up. Therefore, rare earth magnesium treatment is beneficial to effectively remove the impurity elements such as O and S in the steel.