Structural Characteristics of Ductile Iron at Different Rare Earth Contribution from a Magnesium Ferrosilicon Alloy

摘要

The structural characteristics of ductile irons were studied using different rare earth elements (REE) in Mg-FeSi treatment alloys (0.005 - 0.025%REE_(res)), in un-inoculated and Ca-bearing FeSi in the mould inoculated irons. In relatively high purity base iron, in terms of anti-nodularising trace elements, (Thielman factor K = 0.7-0.8), increasing REE content after Mg-treatment aggravated the carbides tendency and decreased the nodular graphite compactness, in both un-inoculated and inoculated irons. Graphite parameters improve for lower REE content, and, in both cases, for inoculated irons. A low content of REE_(res) (0.005 to 0.01%) for K ＜ 0.8 is practical and sufficient in a Ca-bearing FeSi alloys inoculated iron to control carbides sensitivity and to sustain acceptable nodular graphite morphology formation.