Thermal analysis control of in-mould and ladle inoculated grey cast irons

The effect of addition of 0.05wt.% to 0.25 wt.% Ca, Zr, Al-FeSi alloy on in-ladle and in-mould inoculation of grey cast irons was investigated. In the present paper, the conclusions drawn are based on thermal analysis. For the solidification pattern, some specific cooling curves characteristics, such as the degree of undercooling at the beginning of eutectic solidification and at the end of solidification, as well as the recalescence level, are identified to be more influenced by the inoculation technique. The degree of eutectic undercooling of the electrically melted base iron having 0.025% S, 0.003% AI and 3.5% Ce is excessively high (39 - 40℃), generating a relatively high need for inoculation. Under these conditions, the in-mould inoculation has a more significant effect compared to ladle inoculation, especially at lower inoculant usage (less than 0.20 wt.%). Generally, the efficiency of 0.05wt.% - 0.15wt.% of alloy for in-mould inoculation is comparable to, or better than, that of 0.15wt.% - 0.25wt.% addition in ladle inoculation procedures. In order to secure stable and controlled processes, representative thermal analysis parameters could be used, especially in thin wall grey iron castings production.