| 摘要 |
PROBLEM TO BE SOLVED: To produce a round billet for use in production of a seamless steel pipe having no detrimental segregation from a continuously cast square cast metal of a high-Cr, high-Ni, Mo steel.SOLUTION: A method for producing a round billet from a continuously cast square molten metal is provided. In the method, a molten steel having a chemical composition containing in mass%, 0.005 to 0.250% of C, 0.05 to 2.00% of Si, 0.05 to 3.00% of Mn, at most 0.04% of P, at most 0.004% of S, 0.01 to 3.00% of Cu, 10 to 35% of Cr, 10 to 80% of Ni, 1.5 to 10.0% of Mo, 0.001 to 0.300% of Al and 0.001 to 0.300% N with the balance being Fe and impurities is continuously cast into a square cast metal using a casting mold having a flattening ratio w/h of 1.0 or more and 2.0 or less when w and h denote a long-side length and a narrow-side length of the molten metal, respectively, and the obtained square cast metal is formed into the round billet by forging or rolling. |
