The Formation Mechanism of Mn–Al–O Inclusions in Fe–Cr–Mn Stainless Steel during Continuous Casting

Abstract

The formation mechanism of Mn–Al–O inclusions in Fe–Cr–Mn stainless steel during continuous casting is investigated by industrial trials and thermodynamic calculation. The morphology, composition, and size distribution of inclusions in steel specimens are analyzed by scanning electron microscopy and energy dispersive spectroscopy. The main inclusions change from spherical Ca–Si–O and Ca–Si–Mn–O inclusions during LF refining to Mn–Al–O inclusions in continuous casting slab and hot‐rolled sheet. The size of most Mn–Al–O inclusions containing high MnO content is smaller than 4 µm. The formation of these inclusions is consistent with thermodynamic calculation, which indicates that MnO and Al2O3 inclusions are formed during continuous casting process. The calculation results of MnO and Al2O3 inclusions growth shown that the size of MnO inclusion (4 µm) is much larger than that of Al2O3 inclusion (0.4 µm) at the end of solidification, which also accords with the characteristics of inclusions in continuous casting slab and hot‐rolled sheet.