Effect of Al2O3 Content in Inclusions on the Precipitation of MnS During Cooling of a Heavy Rail Steel

In this study, the effect of Al 2 O 3 fraction in Al 2 O 3 –SiO 2 –MnO system inclusions on the precipitation of MnS in heavy rail steels was investigated using laboratory experiments and thermodynamic calculation. Steel samples containing Al 2 O 3 –SiO 2 –MnO inclusions with the fraction of Al 2 O 3 varying from 26 to 94 pct were prepared in laboratory experiments. The content of total oxygen and soluble aluminum was measured. The morphology and composition of oxide inclusions and MnS were analyzed using a scanning electron microscope equipped with an energy-dispersive spectrometer. Results showed that Al 2 O 3 –SiO 2 –MnO oxide inclusions could act as heterogeneous nucleation core of MnS. Both the size and composition of Al 2 O 3 –SiO 2 –MnO inclusions had effects on the precipitation of MnS. Reducing the size of Al 2 O 3 –SiO 2 –MnO inclusions had beneficial effects on the heterogeneous nucleation of MnS during the cooling process in the steel. With the reduction of Al 2 O 3 in