| 摘要 |
PROBLEM TO BE SOLVED: To provide a continuous casting method of a low alloy steel cast slab, with which the development of transverse fracture and transverse crack developed at the straightening of the cast slab even in the case of changing the casting speed or the cast slab size. SOLUTION: When the cast slab having 1.8-10.5 ratio of the width to the thickness is cast, during the section from the starting of cooling just after the outlet of a mold to at least 1.5 m in the casting direction, the cast slab is cooled under condition, in which a value of the water spraying ratio Q (L/kg of steel) of secondary cooling defined with the following formula (A) becomes 0.4-0.75, and the surface temperature of the cast slab is made to not above the Ar3 transformation point and thereafter, returned back to >=850 deg.C to straighten the bending thereof. Q=W/(H×D×Vc×ρ)...(A). Wherein, W: the cooling water quantity (L/min) of the secondary cooling, H: the width (m) of the cast slab, D: the thickness (m) of the cast slab, Vc: the casting speed (m/min) andρ: the density (kg/m3) of the molten steel.
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