The relationship between the variation of eutectic temperature and melt quality in cast iron

摘要

Using a thermal analysis system consisting of three cups (T: Inoculated, U: Base melt, V: tellurium added), the effects of alloying elements on the graphite temperature(TEG, stable system eutectic temperature) and the cementite eutectic temperature(TEC, meta-stable system eutectic temperature) of cast iron and the difference between them(f￠TE) were investigated. This thermal analysis system was used to predict the chill depth and mechanical properties. The order of elements (graphitization elements) that expand f￠TE was found to be as follows: Si> Al> C<2.9%> Cu> Co> P> Ni> C>2.9%. The order of elements (chilling elements) that narrow f￠TE was found to be as follow: B> S>0.44%> V> Cr> S<0.44%> Mn> Nb> Ti> Sn> W> Mo> Sb. f￠TE has a relationship with the distribution coefficient of the element in the interface between cementite and austenite. The chill depth of cast iron can be determined by f￠T1/f￠TE, in which f￠T1 is the difference between supercooling turning point temperature (TSC) and cementite eutectic temperature(TEC). The value of f￠T1/f￠TE shows where the eutectic solidification curve lies between TEG(the eutectic temperature of non-chill melt) and TEC(the eutectic temperature of complete chill melt). f￠T1/f￠TE is a good indicator not only of the chill depth but also of graphite types and tensile strength.