Different cases of transverse corner cracks observed in continuously cast slabs of peritectic steel grades were analyzed. The results of metallographic examination showed that cracks were mainly formed below oscillation marks, running along austenitic grain boundaries. Some evidences were found which indicate that poor lubrication in the mold and mold level fluctuations could have contributed to the initiation of cracks in the mold. However, propagation of cracks was clearly below the mold, probably aided by mechanical stresses during unbending or due to machine misalignments. Therefore several changes were implemented of in order to reduce cracks initiation in the mold and their propagation below it. These actions allowed a significative reduction of slabs downgraded by this defect.
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