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Solidification mechanisms occurring in horizontal continuous casting. part 2: experiences with a ‘HOt’ apparatus; external aspect of the metallic products obtained

Patrice Berthod, Fabien Arnould, Denis Girardin

The metallic products obtained by continuous casting with meniscus-free first skin solidification, notably in horizontal continuous casting, are usually covered by periodically linear defects. To study and explain their formation a “hot” apparatus simulating such process was realized and exploited for the solidification of cast iron, a {low melting point}-iron alloy allowing solidification at temperatures much lower than with steels. The obtained cast iron products, empty tubes and not full ingots as in steel continuous casting, present many types of linear defects: joint marks, junction marks, and for low extraction speeds: wrinckles and vortex. In case of lack of liquid metal feeding, the tube may be emerging with the dynamic skin and the static skin not joined to one another all around the circumference. Furthermore, when the mould was made of graphite, another type of surface defects has appeared on the external tube surface: a couple of two longitudinal linear protuberances present in some case on the same generating line, starting and stopping in both the dynamic skin and on the static skin. These two new observations demonstrated a second time, after the visualization allowed by the ‘transparent’ apparatus in the first part of this work, the twin growth of the first skin.