Fluxes for Ingot Casting

Abstract

Mould powders for ingot casting have, in many ways, the same function as mould powders for continuous casting. However, in some aspects the properties and compositions must meet requirements other than those for continuous casting. After the introduction of continuous casting on a bigger scale and adaptation of mould powder for this technology, the development of ingot casting powder has mainly been based on experience derived from the development of CC mould powders. Thus, there has been little development in casting powder research and ingot casting technology for more than 30 years. The remaining steel grades that are cast by the ingot process route today tend to be high-grade, high-quality steels and there is a new, re-awakened interest in the development of both ingot casting technology and mould powders for ingot casting. Today most ingot casting is carried out with killed steel cast into bottom end up (BEU) ingots. Thus, the most important properties of the mould powders are good flowability and good thermal insulation. The creation of a mould powder slag is important but the thickness and composition of this must be designed according to the steel grade being cast and the process conditions which require careful control of the composition and melting speed. Most ingot powders are still produced with fly ash as a base but the use of synthetic mould powders is growing because of its greater versatility in composition. Granulated powders for ingot casting are also attracting a growing interest, since they are more environmentally friendly, causing much less dust during casting. They also give better flowability, compared to loose synthetic powders, and open up the opportunity of continuous feeding during casting.