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 carburizer, which effects carburization with respect to molten iron accommodated in an electric furnace or a ladle, includes a mixture of quicklime and a carbon material having an ash content of from 5 mass % to 18 mass %, and satisfies the conditions 0.6?(mc+Mc)/ms?2.7 and 0.7?(mc+Mc)/ma?6.5. A method of carburization uses this carburizer. Here, mc represents the mass of CaO in the carbon material, ms represents the mass of SiO2 in the carbon material, ma represents the mass of Al2O3 in the carbon material, and Mc represents the mass of the quicklime.

Abstract: On molten iron having the P concentration of 2 to 4 mass % and having the 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 the P concentration of 1.9 to 3.8 mass % and having the Cr concentration of less than 0.2 mass %.