CONTINUOUS CASTING METHOD

摘要

PURPOSE:To improve the execution rate of direct rolling and to prevent generation of the internal defect of a billet by measuring the ultrasonic wave velocity in the billet, calculating the temp. in the billet from a relation equation and approaching said temp. to a target temp. CONSTITUTION:A noncontacting electromagnetic ultrasonic meter 100 is installed at the end part 23 of a continuous casting device or behind a cutter 24. The transmission time t0 of the ultrasonic wave in a billet 10 at >=3 points in the transverse direction of the billet 19 is determined by using such meter 100. The thickness D0 of the billet 19 in this part is then determined and the average temp. in the thickness direction of the billet 19 is calculated by a relation equation from said time t0 and said thickness D0. The casting speed and/or secondary cooling is controlled to eliminate the difference between the calculated temp. and the target temp. determined separately by each kind of steel.