Abstract: On molten iron having a P concentration of 2 to 4 mass % and having a Cr concentration of 0.3 to 1.2 mass %, a dechromization treatment is performed by adjusting a basicity (CaO mass %)/(SiO2 mass %) of slag to greater than 0.1 and 1 or less and supplying an oxygen source with a molten iron temperature falling within a range of 1250 to 1500° C. to manufacture molten iron having a P concentration of 1.9 to 3.8 mass % and having a Cr concentration of less than 0.2 mass %.

Abstract: A method of producing molten steel supplies gaseous oxygen from a top blowing lance into a converter to perform decarburization refining of molten iron while adding a CaO-containing powdery dephosphorizing agent to simultaneously decarburize and dephosphorize the molten iron and includes supplying the dephosphorizing agent to a bath surface of the molten iron together with at least one gas jet from the top blowing lance and a dynamic pressure determined when a gas jet blown from respective lance nozzles of the top blowing lance impinges onto the bath surface of the molten iron is controlled to not more than 0.50 kgf/cm2.

Abstract: A cast steel with excellent workability, characterized in that not less than 60% of the total cross section thereof is occupied by equiaxed crystals, the diameters (mm) of which satisfy the following formula: D<1.2X1/3+0.75, wherein D designates each diameter (mm) of equiaxed crystals in terms of internal structure in which the crystal orientations are identical, and X the distance (mm) from the surface of the cast steel. The cast steel and the steel material obtained by processing the cast steel have very few surface flaws and internal defects.

Abstract: For the metallurgical treatment of a molten metal bath (1) in a metallurgical smelting and refining vessel (3), additive substances (43) which are capable of flow, in particular lime, are supplied in a granular to dust state, at least during a part of the refining phase, to the upper region of the inward side (15') of the vessel wall (11), distributed around the periphery thereof. At the vessel wall (11) the additive substances (43) form a barrier or protective layer which reduces the energy losses and increases the service life of the vessel (3).