Development of a New Mold Oscillation Mode for High-speed Continuous Casting of Steel Slabs

High-speed continuous casting is a prerequisite for the successful operation of hot direct rolling (HDR). However, as casting speed increases, breakout caused by solidified shell sticking tends to occur. It is therefore necessary to reduce the frictional force between the mold and the solidified shell in order to prevent shell sticking in high-speed casting. The lubrication mechanism in the mold was analyzed, and the results led to the establishment of a new modl oscillation mode which reduces frictional force. This offers an oscillation movement where the time of upward motion of the mold is longer than that of downward motion in a single oscillating cycle. The effect of this new mode on the reduction of the frictional force was ascertained by casting tests using an experimental continuous caster. On the basis of fundamental studies the new mold oscillation mode has been utilized in the No. 5 slab caster at NKK Fukuyama Works. Plant tests confirmed that the new mode is more effective in reducing frictional force than the sinusoidal mode. A high-speed casting of 3.0 m/min has been successfully achieved with this new mold oscillation mode. No difference in the surface quality of slabs could be observed between casting with the sinusoidal mold oscillation and this new mode.