Chill (Carbide) control in low sulphur electric melt grey cast irons

摘要

Ca, Ba and Ca-Ba bearing FeSi alloys were compared for their effectiveness in chill (carbide) control, using iron chemistries with critical element levels [< 0.035%S, (%Mn) × (%S) < 0.02, <0.003%Al]. Relative clear and total chill measurements were employed, for chill wedges with different cooling modulii (CM = 0.11 - 0.35 cm). Previous experiments illustrated that the eutectic undercooling of this type of base iron is excessively high, demonstrating a relatively high need for inoculation. Under these conditions, Ca inoculation had a significant effect compared to Ba inoculation, while a Ca-Ba combination improved most of the solidification parameters. The results also illustrate the importance of residual Al and confirm its key role in graphite nucleation in grey irons. The content of the active elements (Al, Ca, Ba) in FeSi based alloys appears to be more important if they inoculate low sulphur irons, more so than increasing the addition rate of an unsuitable inoculant composition.