To provide steel sheet continuous annealing equipment which performs heat treatment of various thin steel sheet product ranging from a mild steel sheet to an ultrahigh tensile steel sheet, and to provide a method for operating the equipment.
(1) The steel sheet continuous annealing equipment includes a preheating zone, a heating zone, a soaking zone, a cooling zone, a reheating zone, an overaging zone and a final cooling zone, in this order, and further includes a rapid heating region and a rapid cooling region that are provided within a rage form the reheating zone to the final cooling zone (containing the reheating zone and the final cooling zone), the rapid heating region allowing the steel sheet to be rapidly heated at a heating rate of ≥15°C/sec and the rapid cooling region allowing the steel sheet to be rapidly cooled at a cooling rate of ≥10°C/sec. (2) In the steel sheet continuous annealing equipment, the rapid heating region is provided in the overaging zone and the rapid cooling region is provided between the overaging zone and the final cooling zone or in the final cooling zone, etc.
NAKAYAMA SHINOBU
MURAKAMI TOSHIO
Makoto Suhara
Takenaka Yoshimichi