| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a flat casting lump for a material for a thick steel plate of Ni steel by a downward pouring casting method, with prevention of shrinkage defect.SOLUTION: The method is configured such that: a feeder part volume ratio is 0.1-0.2; the maximum thickness T0 of an upper end surface of a casting lump body is 850-1150 mm; when the maximum thickness of the casting lump body is T1 at a position lower than the upper end surface of the casting lump body by h=T0/3, a casting die taper ratio: Z=(T0-T1)/h×100 is 7.5-9.0%; lower part molten metal surface rise speed: V1[m/min]=(H-h)/1000/t1 is 150/{(10.5-Z)×T0}≤V1≤300/{(10.5-Z)×T0}; and upper part molten metal surface rise speed: V2[m/min]=h/1000/t2 is 60/{(10.5-Z)×T0}≤V2≤120/{(10.5-Z)×T0}. (H is height of the casting lump body [mm], t1 is time since start of molten steel pouring to reaching of the molten metal surface to a position lower by h [min] and t2 is time until the molten metal surface reaches to an upper end surface of the casting lump body from the position lower by h [min]). |
