| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to secure the ferrite transformation of an entire cast steel product without excessively cooling the cast steel product, and to realize the prevention of surface flaws after hot-rolling a rolled steel product using the cast steel product as a raw material and the improvement of the tenacity of the entire rolled steel product.SOLUTION: Necessary water cooling time required to set a surface temperature of a water-cooled cast steel product to be equal to or lower than a ferrite transformation temperature while an internal temperature of the water-cooled cast steel product to exceed the ferrite transformation temperature, and necessary air cooling time required to set the surface temperature and the internal temperature of the water-cooled cast steel product to be equal to or lower than the ferrite transformation temperature are set. The cast steel product is water cooled for the set necessary water cooling time, and the water-cooled cast steel product is air cooled for the set necessary air cooling time. |
