抄録
An investigation has been made of the quality of continuous-casting slabs and especially of the inner large inclusions for one year since No 1 continuous-casting machine at Kashima Steel Works started.
The results obtained are summarized as follows:
(1) Number of inclusions in molten metal at tundish increases as the heat proceeds in sequent-casting. For example its ratio at three-heats-casting 1: 3: 10. It is presumed that the principal origin of this increase of ratio is slags in tundish poured out from ladle.
(2) Generally, the inner inclusions of slabs are considered to originate from the following three:
The first is the oxides which are produced when the metal is oxidized by the air in tundish and/or between ladle and tundish. The second is the ladle slag pouered out to tundish and the lining of tundish.
The third is the powder added to the mold. Therefore the inner inclusions in continuous-casting slabs are compounded with those three origins.
(3) The number of the inner inclusions of slabs decreases as the angle of immersed nozzle becomes smaller. It seems, however, that the location of the inner inclusions in the slab is almost the same independent of the angle of immersed nozzle.
