METHOD FOR CONTINUOUSLY CASTING CAST SLAB FOR ULTRA-THICK STEEL PLATE

摘要

PROBLEM TO BE SOLVED: To provide a method for continuously casting a cast slab as a blank for producing a high strength ultra-thick steel plate excellent in the inner quality having no defect in an ultra-sonic flaw examination by using the existing rolling mill for thick plate. SOLUTION: In the continuous casting method for the cast slab to be used as the blank for ultra-thick steel plate excellent in the inner quality obtained by hot-rolling on the condition that a rolling-reduction ratio (r) till finish-rolling is 1.5-2.5, one pair of upper and lower rolling-reduction rolls disposed in the continuous casting machine or the end of this machine is used to continuously cast the cast slab for ultra-thick steel plate, wherein the width center part of the cast slab containing non-solidified part is rolled in the range of the rolling-reduction amount d(mm) where the center porosity volume Vpo(cm3/g) of the cast slab satisfies the relation of 0.15×10-4≤Vpo≤0.9×10-4, in the range of 0.8 to<1.0 of a solid phase ratio at the thickness center part. COPYRIGHT: (C)2008,JPO&INPIT