| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for continuously casting a round cast slab for making a high Cr seamless steel pipe, sufficiently restrained at a practical level from the occurrence of a crack at an axis part, particularly a shrinkage hole formed in the last stage of coagulation and an A-type crack caused by the shrinkage hole as well as a C-type crack, and having a small cast slab camber.SOLUTION: In continuously casting a round cast slab for making a high chromium steel seamless steel pipe, a strand containing uncoagulated molten steel inside is subjected to axis part coagulation former stage forced cooling with a water quantity density Qof 30-90 L/m/min over at least a section from a position at which the axis part solid phase ratio fs of the strand is 0.2 up to a position at which the fs is 0.5, and then is subjected to axis part coagulation former stage forced cooling with a water quantity density Qof 20-60 L/m/min smaller than the cooling water quantity density at the end of the axis part coagulation former stage forced cooling, over at least a section from a position at which the fs is 0.8 up to a position at which the axis part temperature of the strand is (Ts-145)°C. |
