Design of Mold flux

There are specific requirements of mould flux for specific grade of steel. For example,low carbon aluminum killed steel requires flux which can absorb  inclusion without an adverse effect on viscosity. A lower viscosity helps the flux provide sufficient lubrication at higher casting speed.

Medium carbon grades  are prone to cracking. High solidification temperature of flux reduces heat through mold. For adequate lubrication low viscosity of the flux is required.

High carbon grades too require flux of low viscosity and melting point.

Ultra low carbon steels  requires flux which can absorb non metallic inclusions, improve insulation, provided good lubrication, stable properties and minimal slag entrapment.

Table gives effect of chemical composition on mold flux properties.

The table can be read as for example increase in CaO decreases viscosity but increases solidification and melting temperature of the flux. Similarly the effects on other constituents on the viscosity and solidification/melting temperature can be understood.