Abstract
The content of soluble oxygen during cooling, inoculation and solidification of Fe-C and Fe-C-Si alloy melts were measured by the oxygen concentration cells with the solid electrolyte of mullite. It was possible to detect the transitional critical temperature from C-O reaction to Si-O reaction during cooling. The transitional critiical temperature is lower than the critical equilibrium temperature. This means that considerable undercooling is required to accelerate the Si-O reaction. Above the critical temperature, the soluble oxygen content near the solid SiO2 is higher than the equilibrium value. Immediately after the Si-inoculation, the soluble oxygen content falls abruptly and recover to the constant level. This means that the Si-inoculation process contains the deoxidization process of the melt. In the beginning of eutectic solidification, the soluble oxygen content of melt increases by its redistribution during the solidification.
