Carbon Pickup in Continuous Casting Processes

The quality of the as-cast strand is influenced by a recarburization reaction since mould powder contains carbon particles necessary for a controlled melting behaviour. Intensive testing reveals a carbon pickup in the surface of the as-cast strand depending on content and type of the carbon in the mould powder. Using the combination of laboratory trials and numerical simulations the effect of carbon pickup from mould powder to the strand shell was investigated. Laboratory experiments show that the recarburization of the liquid steel through the mould powder can be explained by Marangoni convection. This can happen in the slag rim when the carbon is entrapped by the solidifying steel and starts to diffuse inwards the strand.