Extraction, Distribution, and Precipitation Mechanism of TiN–MnS Complex Inclusions in Al-Killed Titanium Alloyed Interstitial Free Steel

The TiN–MnS complex inclusions in Al-killed titanium alloyed interstitial free steel were extracted from the slabs using an electrolytic aqueous solution method. Scanning electron microscopy with energy spectroscopy analysis and an automatic scanning electron microscope were employed to analyze the size and distribution of TiN–MnS inclusions in the thickness direction of the slab. It was found that TiN–MnS complex inclusions were primarily concentrated in the 1/4 thickness direction from the inner and outer surfaces, and the size of the complex inclusions in the slab center was approximately 8 μm. TiN began to precipitate when the solidification rate reached 0.646–0.680 in the δ phase, and MnS would appear in the γ phase when the solidification rate exceeded 0.450 through thermodynamic analysis. Also, the formation mechanism of the complex TiN–MnS was investigated under a crystal structure during solidification. Graphic Abstract The TiN–MnS complex inclusions in Al-killed titanium alloyed interstitial free steel were extracted from the slabs using an electrolytic aqueous solution method. Scanning electron microscopy with energy spectroscopy analysis and an automatic scanning electron microscope were employed to analyze the size and distribution of TiN–MnS inclusions in the thickness direction of the slab. It was found that TiN–MnS complex inclusions were primarily concentrated in the 1/4 thickness direction from the inner and outer surfaces, and the size of the complex inclusions in the slab center was approximately 8 μm. Due to the similar plane of atoms ((100)TiN||(100)MnS and [001]TiN||[001]MnS) and a semi coherent interface between TiN and MnS, a series of edge dislocations would provide a comfortable accommodation for misfits parallel to the interface.