Area method analysis and thermodynamic behavior of nonmetallic micro-inclusions in casting slab of GCr15 bearing steel

The distribution and characteristics of nonmetallic micro-inclusions of GCr15 bearing steel were explored through metallographic area method in virtue of tracer method and electronic microscope. The results show that the micro-inclusions, of which the average value is 0.032%, are mainly the compounds formed via the adsorption/aggregation of multielement deoxidized compounds and secondarily deoxidized products on tundish liquid level. The micro-inclusions of diameters from 0 to 5 μm are 92.5% in total, which basically determines the characteristics of inclusions distribution in casting slab. The inclusions of diameters more than 10 μm only account for less than 1% in total, which have little influence on steel quality. The relationship between equilibrium compositions of the first deoxidation products and molten steel compositions was also calculated based on thermodynamic theory. © Tianjin University and Springer-Verlag 2009.