The Formation Mechanism of Center-line Cracking on the Continuous Cast Slab

Continuously cast slab may contain linear cracks in the middle of the slab thickness.This crack is called the centerline cracking.In many cases, the cavity cannot be closed through the rolling process and presents itself as a defect. In this paper, the formation mechanism of center-line cracking has been discussed on the bases on investigation of center-line cracking and analysis of relevant operating conditions. The results are summarized as follows, (1) Center-line cracking is a shrinkage cavity created through the solidification of molten steel closed off in the vicinityof final stage of liquid core. (2) The enclosed liquid thickness calculated from the cavity data is about 6mm. (3) The defect intervals of slabs coincide with the circumference of the roll in the neighborhoodof the unbending point. (4) Center-line cracking is apt to occur when the slab is cast in the crack-sensitive range.