New approaches of the initial solidified shell formation mechanisms in the continuous casting mould. Technical Steel Research. Casting and solidification

Abstract

The work carried out in this ECSC project led to the development of new knowledge and new tools for the improvement of the surface quality of continuously cast products. Numerical tools useful for the calculation of the thermal field in the mould plates, the mould flux infiltration and the first shell solidification, including the oscillation mark, were developed and fitted with industrial data. A numerical model for multiphase non-steady computations was set up, taking into account argon gas bubbles, the non-metallic inclusions and the dynamic steel-slag interface. A physical full-scale water model was also used. The impact of many casting parameters can be quantified using these tools. Slag rims were sampled on industrial casters and showed there is no general case for their formation mechanism and behaviour during casting. A new specific laboratory experiment was implemented to characterise the heat transfer between the steel shell and the mould in the case of oil lubrification. Several oils were tested showing different behaviour in terms of heat transfer and gas release. High-speed video at the meniscus of an industrial caster showed that liquid oil remains at the liquid steel meniscus leading to instabilities due to burst out of oil pockets. The mechanism of formation of the black deposit at the mould wall, which plays an important role to avoid steel sticking against the mould, was analysed. This deposit arises from evaporation of the most volatile steel compounds or tramp elements and condensation.