PURPOSE: To prevent the deterioration of quality at the head end and the tail end of a coil of hot rolled high tensile strength steel plate by performing coiling at specific cooling velocity in specific temp. range after finish rolling in specific temp. range.
CONSTITUTION: At the time of exerting hot rolling by using a slab of a steel having a composition consisting of, by weight, 0.03-0.10% C, ≤0.10% Si, ≤0.5% Mn, 0.03-0.5% Nb, 0.02-0.10% P, and the balance iron with inevitable impurities as a stock, a sheet bar passed through a roughing stage is temporarily coiled and the subsequent finish rolling is started at 730-880°C and, continuously after rolling, the resulting plate is cooled within 0.5sec at ≥50°C/sec cooling rate and coiled at 300-700°C, by which the hot rolled high tensile strength steel plate excellent in uniformity of quality can be produced.
SAEKI MAKOTO
KATO TOSHIYUKI
Next Patent: PRODUCTION OF HOT ROLLED STEEL PLATE HAVING HIGH WORKABILITY AND HIGH TENSILE STRENGTH AND EXCELLENT...