| 摘要 |
PROBLEM TO BE SOLVED: To provide a rolling method by which a continuously cast slab having high flatness ratio as a base stock for seamless steel tubes made of high-Cr-containing steel can be bloomed without generating surface flaws. SOLUTION: In this method, when rolling a continuously cast slab made of high-Cr-containing steel ( Cr≥8% ) into a round billet of a base material for manufacturing seamless steel tubes, a cast slab having a rectangular cross section which is≤0.5 in the ratio d/C of the target diameter (d) of the round billet to the length (C) of the short side of the continuously cast slab is used, or, under conditions of the ratio d/C of > 0.5, a cast slab having a rectangular cross section which is≤0.7 mm in the depth of oscillation marks on the surface of the cast slab,≥1.5 in the ratio A/C of the length (A) of the long side to the length (C) of the short side and the ratio d/C of which satisfies the relationship expressed by the next formula. Where, the formula is expressed by d/C < -0.041×(A/C) + 0.997. COPYRIGHT: (C)2005,JPO&NCIPI
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