Mould powder investigations for high speed casting

Abstract

Mould powders significantly determine the stability of the continuous casting process of steel. The processes leading to melting of mould powder and solidification of mould slag were studied in situ using high temperature X-ray diffraction with additional powder X-ray diffraction and microscopic techniques. It was shown that during heating, a powder shows a specific sequence of phase relations before melting takes place. During cooling and solidification, one or more crystalline phases can be formed. The findings on high temperature properties were confirmed by the analyses of slag rims and slag films, obtained from the Corus thin slab caster. Finally, the in depth characterisation, together with some calculations on mould slag was compared with plant data of the thin slab caster. Results from this work give a better understanding of the mould powder functions at the thin slab caster and are being used to guide mould powder design for the current and even higher casting speeds.