| 摘要 |
PROBLEM TO BE SOLVED: To enable fining the inclusion by continuously casting molten steel containing specific quantities of SiO2, bivalent oxide and Al2O3 in the composition of particles floated in the molten steel and controlling the m.p. with a specific temp. of silicate, forming as a cast slab and hot-rolling with a specific temp. and a specific time. SOLUTION: The composition of the particles floated in the molten steel 2 is regulated to 30-70%; SiO2, 20-60% bivalent oxide (MnO+CaO+MgO) and 10-30% Al2O3. The molten steel 2, in which the m.p. of the particles is controlled with the silica having <=1400 deg.C, is supplied into a continuous caster 3 and formed as the cast slab 4. The cast slab 4 is drawn out downward from a mold 5 and cooled with water spouting device 6 and drawn around 3/4 circumference. The cast slab is executed over the casting surface L and the molten core is left to the atmosphere corresponding state iron pressure height (about 1.4 m) Q point, and the cast slab is formed as a hollow cast slab 9. The hollow cast slab 9 is in press-contact with the inner surface with a press-contact rolling mill 10 and formed as a solid cast slab 11 and directly supplied into a wire rod rolling mill 12 and formed as a wire rod 13. During this operation, the cast slab 4 is hot-rolled within 30 min in the temp. state at >=900 deg.C.
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