TEM analysis of centreline sulphide precipitates modified by titanium additions to low carbon steel

Elongated inclusions, particularly MnS, contributesignificantly to reduced ductility and toughness in hotrolled steel but earlier research indicated that these propertiescan be improved by titanium additions. Such additions to asteel result in titanium being dissolved in manganese sulphideor MnS being replaced by TiS and/or titanium carbosulphides.In the present study, a steel was designed to decrease alloyingelement segregation and to evaluate the effect of titanium oncentreline sulphide precipitates. Precipitates were identifiedby using scanning electron microscopy and characterizedby the use of transmission electron microscopy followingsample preparation by focused ion beam milling techniques.Irontitanium-sulphides form in close proximity to MnSprecipitates that contain iron. Evidence is provided that anincrease in the titanium content of steel leads to an increasein the percentage of titanium contained in the iron sulphidesand a decrease in the iron content of MnS inclusions.