JPS5614063A - Continuous casting method - Google Patents

Abstract

PURPOSE:To lower the machine height and decrease casting defects as well by making the leveling internal strain rate of a slab at each leveling point of the multi- point leveling curving type continuous casting machine less than the specific value and gradually decreasing the spacings between the upper and lower rolls from the end point of leveling up to the position of freezing end point. CONSTITUTION:Casting is performed by making the leveling internal strain rate epsilonN expressed by the formula within a range of <=0.35% and gradually decreasing the spacings between the upper and lower rolls in the horizontal part from the end point of leveling up to the freezing completion point. The machine has 5 points of leveling points, P1-P5, and further it has a taper alignment region T consisting of 14 pairs of roll groups of varying spacings between the upper and lower rollers. The curving radii R1-R5 at the respective leveling points have different values; they become gradually larger, like R1 5,800mm. and R5 7,100mm.. Here, a slab sizing 410X1,700mm. is cast at a speed of 0.5m/min. The frozen shell thickness at the leveling point P1 is 110mm. and the rate of freezing is about 54%. Hence, the leveling strain rate at the leveling point P1 is 0.28%, below the specific 0.35%, and the respective strain rates of P2-P5 become nearly the same values. The rate of occurrence of cracking to halves of the slab cast in this way is just 1-2%.