| 摘要 |
PURPOSE:To reduce the development of longitudinal crack by specifying the distance between position, where molten steel discharging flow from a submerged nozzle having two holes collides to solidified shell, and meniscus in a mold at the time of pouring middle carbon steel at high speed. CONSTITUTION:The middle steel containing 0.09-0.16% C is discharged to short side face of the mold 2 from the submerged nozzle 1 having two holes, and also by using lubricating powder, a slab is cast at >= 1.1 m/min casting speed. Then, the discharged flow F of the molten steel is split into ascending flow and descending flow while colliding to the solidified shell S, and while washing the shell S. the ascending flow is reached to the meniscus 3 in the mold and by changing flow direction, it is flowed toward center of a long side face. In this continuous casting process, at the time of using W for width (mm) of the slab, theta for discharging angle (nozzle angle) inclined downward to the horizontal line and (d) for depth (mm) from the meniscus 3 to center of the discharging hole, the distance H from the position, where the discharged flow F collides to the shell S, to the meniscus 3, is to be 200-350 mm. |
