PURPOSE: To perform a hot rolling of a steel sheet having a superior surface property without the generation of scale defects on the surface, red scale and cooling irregularity in a controlled cooling.
CONSTITUTION: At least one descaling is performed with a high pressure water having an impact pressure of 38kgf/cm2 before the start of a roughing and also before the start of a finish rolling. In addition, in the finish rolling process 7, a hot rolling is performed with a pass schedule for a larger draft to give the limit value HS of the scale layer thickness such that the destruction of the scale layer is not caused in a roll bite at the time of rolling reduction. HS=a.γ2+b.γ+c, where HS: limit value of scale layer thickness; γ: rolling reduction; a, b, c: coefficient to be determined by kinds of steel and rolling temperature.
KATO AIICHIRO
MORIMOTO SADAO
MIYAWAKI ATSUSHI
OBANYA YOSHIKAZU
FUJINO TAKANARI
