Method for continuously casting slab

A method for continuously casting a slab using a curved type or vertical bending type continuous casting machine, the method comprising:

• the step of cooling the slab just beneath a mold in a secondary cooling zone, the slab being withdrawn from the mold, the step further comprising:
• a first water cooling step, a first recuperation step that follows the first water cooling step, a second water cooling step that follows the first recuperation step, and a second recuperation step that follows the second water cooling step,
• wherein the first water cooling step is a step of cooling the slab of which a surface temperature is no less than 1000° C., by supplying cooling water to wide surfaces of the slab, including that only a surface temperature of a corner part is below Ar3 point, and a surface temperature of a portion of the slab other than the corner part is kept no less than Ar3 point, the corner part being a region within 20 mm from an apex and edges of the slab,
• the first recuperation step is a step of recuperating the slab including that the surface temperature of all the slab including the corner part is no less than the Ar3 point,
• the second water cooing step is a step of cooling the slab of which the surface temperature is the Ar3 point to 900° C., by supplying the cooling water to the wide surfaces of the slab, including that the surface temperature of all the slab including the corner part is below the Ar3 point, and
• the second recuperation step is a step of recuperating the slab including that the surface temperature of the corner part is kept below the Ar3 point, and the surface temperature of the portion of the slab other than the corner part is no less than the Ar3 point.