Abstract
It was observed that the macro structures of carbon steel slab produced by S type continuous wide slab casting machine were asymmetrical, that is, columnar crystal was generated in the upper site of the slab and branched columnar crystal or equiaxed crystal was generated preferentially in the under site.
In order to clarify the cause for above-mentioned asymmetric feature, various investigations, model experiments with water and many operation tests were carried out.
The results obtained are as follows:
(1) The formation of macro structures of continuously cast steel slab was intensitively affected by “Inclination of strand (d.h. gravity)” and “unsolidified steel convection in the shell”. In view of this consideration. The formation process of macro structures was able to be separated into three zones.
(2) Branched columnar crystal formed in the under site of C. C. slab is different from branched columnar crystal formed in steel ingot.
(3) Conditions of equiaxed crystal formation in continuously cast steel slab are formation of lots of nucleus in liquid steel contacted by copper mould and transport of them to the zone of slow freezing rate inside the liquid crater of continuously cast strand.
(4) The formation of center segregation is independent of contact of columnar zone in the center position of continuously cast slab.
