Non-metallic inclusions and acicular ferrite in low carbon steel

The formation of nan-metallic inclusions with variations in various oxygen, nitrogen and titanium contents in low carbon steels has been studied. The relationship between the nature of non-metallic inclusions and the formatio n of acicular ferrite has been also investigated. It is found that the non- metallic inclusions observed in this study are mainly consist of Ti2O3 and TiN together with a small amount of other complex oxides containing Mn and Si. It has been confirmed that Ti2O3 and TiN play an important role in form ation of acicular ferrite as a nucleation site and an austenite grain refin er, respectively. But it is not clear yet whether TiN acts as a nucleation site or not. It is also found that the volume fraction of inclusions is mor e effective than the type or size distribution of the non-metallic inclusio ns on the formation of acicular ferrite.