Abstract
In order to understand the mechanisms of internal cracks formation in the continuously cast slabs by a bow type machine in Hirohata works, influences of casting conditions have been surveyed. Metallographic structure near the internal cracks has been investigated, and by means of autoradiography, generation and growth of internal cracks have been estimated. The results obtained are as follows:
1) As far as the investigated casting conditions are concerned, major cause for the internal cracks is the stress arising from correcting of bulging, which mainly depend on casting speed and specific rate of cooling water. Influences of solute elements are also recognized.
2) Internal cracks are formed adjacent to the solid-liquid interface, where solute enriched liquid penetrates into the crack in solid phase. As a result of repeating the above phenomena taking place by the correcting of bulging, internal cracks are considered to grow gradually.
