Composition evolution and deformation of different non-metallic inclusions in a bearing steel during hot rolling

The composition evolution and deformation of different non-metallic inclusions in a bearing steel during hot rolling were investigated by the automatic detection and the improved non-aqueous electrolysis method. Manganese sulfide, MnS–TiN, and liquid CaO–Al2O3 inclusions were elongated while TiN and MgO⋅Al2O3 were fractured during hot rolling. The CaS–MnS phase in the MgO–Al2O3–CaS–MnS inclusion was separated from the inclusion, leading to the formation of CaS–MnS type clusters. Meanwhile, the CaS and MnS contents in oxide-containing inclusions decreased while the MgO and Al2O3 contents increased after hot rolling. The deformability of different inclusions in the bearing steel was quantitatively compared and discussed.