Relationship between Variation of Eutectic Temperature and Melt Quality in Cast Iron

Abstract

  Using a thermal analysis system consisting of three cups (First : Inoculated, Second : Base melt, Third : Te added) , the effects of alloying elements on graphite eutectic temperature and cementite eutectic temperature of cast iron and their differences (ΔT_E)were investigated. This thermal analysis system was used to predict the chill depth and mechanical properties.
  The order of elements (graphitization elements) that expand ΔT_E is as follows : Si > Al > C_CE<3.5%> Cu > Co > P> Ni > C_CE≧3.5%. The order of elements (chilling elements) that narrow ΔT_E is as follows : B> S_≧0.45%>V> Cr> S_<0.45%> Mn> Nb> Ti> Sn> W> Mo> Sb. ΔT_E is related to the distribution coefficient of elements between cementite and austenite. When S and Mn coexist, the eutectic temperature and graphite shape are determined by soluble S and soluble Mn. The chill depth can be determined by eutectic graphitization ability (ΔT₁/ΔT_E). There is a good relationship between ΔT₁/ΔT_E and graphite type and tensile strength. We can conclude that ΔT₁/ΔT_E serves as an efficient method for predicting melt quality in cast iron.