Modification of Oxygen and Sulphur Inclusions in Steel by Calcium Treatment

The non-metallic inclusions are inevitable consequence of metal elaboration processes and are foreign phases always present in solid and liquid metal. The inclusions have a different shape and a size from several to several hundred micrometers (in diameter). They are randomly distributed in the matrix of the base metal and form a dispersion phase in liquid and in solid metallic phase. The non–metallic inclusions may directly affect the functional properties of metals, especially steel which is commonly used constructional material. The reducing the contents of non-metallic dispersion particles in the metal and the introducing of modification process are significant methods for their decreasing the unfavourable effects. The modification is a process of adding to a metal bath a small amount of substance (i.e. a modifier) which changes the physical-chemical properties of inclusions. The modifiers are metallic substances that change the solid oxide and sulphide particles steel bath to liquid inclusions in liquid metal. In this paper the results of modifications of oxide and sulphide inclusions in steel with calcium, especially in respect of change in theirs shape and deformability are presented and discussed.