| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a steel sheet, capable of stably producing the high-quality steel sheet in which surface defects such as blisters are difficult to be generated.SOLUTION: A continuous casting machine equipped with a pair of upper magnetic poles and a pair of lower magnetic poles is used to cast a slab by continuous casting of steel, while controlling the flow of molten steel by means of direct-current magnetic fields to be applied respectively to the upper magnetic poles and the lower magnetic poles. The slab is hot-rolled to make a hot-rolled steel sheet, and then the hot-rolled steel sheet is cold rolled after it is acid-pickled. At this time, the time t or/and the maximum surface temperature T of the steel sheet is controlled so as to satisfy formula (1): Hc/Ho>exp{-0.002×(T+t/100)}, wherein Ho represents hydrogen concentration in the steel sheet immediately after the termination of acid pickling (in mass ppm), Hc represents critical hydrogen concentration in the steel sheet immediately before cold rolling, which produces poor surface quality due to blisters, and is determined by cold rolling condition (in mass ppm), t represents the time after the termination of acid pickling till the beginning of cold rolling (in seconds), and T represents the maximum surface temperature (K) of the steel sheet before the beginning of cold rolling after the termination of acid pickling. |
