Effects of alloy elements on ductility and thermal conductivity of compacted graphite iron

Abstract

The influence of Si, Sn, Mo and Ni on the ductility and thermal conductivity of compacted graphite iron (CGI) was investigated. Metallographic observation and Differential Scanning Calorimetry (DSC) experiments were carried out to analyze the roles of various additions in the eutectoid reaction. The experimental results showed that the ductility of CGI is proportional to the ferrite fraction, so moderate Si content could dramatically improve the ductility by increasing the ferrite fraction. DSC measurements showed that Mo has moderate inhibition on eutectoid transformation during both the heating and cooling processes, while the sample without Sn obviously broadens the three-phase region. Vermicularity and ferrite are known to improve thermal conductivity, and the former plays a more important role. Besides, among the alloy elements investigated, Sn has the greatest negative effect on conductivity, followed by Ni and Mo having the smallest effects.