Investigation into the Evolution of Microstructure and Mechanical Properties of Compacted Graphite Iron under Elevated Temperature

This paper investigates the evolution of ultimate tensile strength, microstructure and thermal conductivity of compacted graphite iron (CGI) under thermal exposure and vacuum at elevated temperatures. By comparing the properties and microstructure variation of CGI, the oxidation of CGI has a 3D connectivity characteristic under thermal exposure, which will deteriorate the mechanical properties and thermal conductivity of the material at elevated temperature. In this investigation, the relationship between connectivity of oxidation, holding time and oxygen diffusion depth under thermal exposure at 500 °C was established. The influence mechanism of oxygen diffusion depth on tensile strength and the influence mechanism of holding time at elevated temperature on thermal conductivity were proposed by comparing the properties under different conditions. All the results of the investigation will help engineers develop a deeper understanding of CGI materials.