| 摘要 |
PROBLEM TO BE SOLVED: To improve toughness of a steel product by lessening the size of nitrides in the thickness midsection of a cast slab in the continuous casting process of a steel containing Al, Ti and B.SOLUTION: A continuous casting method includes roll-reducing a cast slab at a roll-reduction rate of 5-50% in such a range that a central solid phase rate is higher than 0 but lower than 0.8 in the continuous casting process of the steel containing by mass, 0.005-2.0% Al, 0.005-0.2% Ti and 0.0002-0.005% B. In the continuously cast slab, the ratio (d/d) of the size dof an inclusion in the range of ±25 mm of the center of cast slab thickness to the size d(circle equivalent diameter) of nitrides, BN, TiN and AlN (inclusion) in the range of ±25 mm to 1/4 position of the cast slab thickness is 1.0 to 2.0. Thereby, the above method enables production of the cast slab whose inclusion in the thickness center area of the cast slab is fine and whose internal quality is favorable.SELECTED DRAWING: None |
