The influence of induction hardening on the impact wear resistance of compacted graphite iron (CGI)

The aim of this work was to study the impact wear resistance of untreated and induction hardened compacted graphite iron (CGI). Testing was carried out on a bespoke impact wear test rig to look at the effect of the material properties, before and after hardening, on the level of wear. Three different types of specimen were tested; untreated CGI, CGI induction hardened to a nominal depth of 2 mm and CGI induction hardened to a nominal depth of 3 mm. Worn specimens were measured, optically and directly, and then analysed to characterise the likely wear mechanisms and wear debris. The induction hardening improved the impact wear resistance of the compacted graphite iron and when compared to the laser hardened cast iron it performed much better. Considering the proportion of wear in the valve and valve seat contact that is due to impact wear, it is likely that locally induction hardening a compacted graphite iron cylinder head could be a method of controlling the level of valve recession.