Pieces of mould flux film obtained from a commercial continuous casting machine and measurements of the mould temperature have been used in an investigation to explain the mechanism of heat transfer in the mould. Comparison with the results of numerical calculations, indicates that the main factor responsible for the reduction of heat transfer with a high basicity flux is the contact resistance at the interface of the mould wall and solid flux film. The results show that a relatively high contact resistance is introduced when using a crystalline, high solidus mould flux because of the stability of the contact resistance.
