SURFACE-DEFECTS ON CONTINUOUS-CAST STEEL INGOTS

An analysis is made of the literature data on the causes of surface cr acks in steel semifinished products produced on continuous casters wit h water or water-and-air cooling. It is shown that crack nucleation (g eneration) is chemical in nature. Crack growth during thermoplastic tr eatment of the semifinished product obeys the laws of mechanics and is facilitated by first-order phase transformations, cyclic changes in t emperature, and other phenomena that increase elastic stresses. Conclu sions are reached as to the causes of the nucleation of different type s of cracks.