CHARACTERIZATION OF NON-METALLIC INCLUTIONS IN HOT ROLLED CALCIUM TREATED STEEL

Abstract

A study of the relationship between inclusions’ shape and composition in hot-rolled calcium treated industrial steel was undertaken in this work. Scanning electron microscope equipped with an energy dispersive X-ray (EDX) analyzer was used to analyze the elemental composition of the inclusions. The analyzed elemental compositions were converted into their respective thermodynamically most stable oxides and sulphides, and appropriate phase diagrams were used to determine their formulae. Results obtained reveal that complex oxysulphides and CaO.Al2O3 compound of very small sizes remain undeformed. 12CaO.7Al₂O₃ compound deformed and fractured into strings. 12CaO.7Al₂O₃ containing small amount of CaO.Al₂O₃ deformed plastically. While inclusions that deform into short plastic threads and brittle strings mixed together are made up of small amounts of 3CaO.Al₂O₃ compound in the core of 12CaO.7Al₂O₃. The undeformed (irregular shaped) parts of some of the inclusions were found to contain CaO.Al₂O₃, Al₂O₃.MgO and 2Al₂O₃.3CaO.MgO compounds.