Comparison of the tribological behavior of quench-tempered ductile iron and austempered ductile iron with similar hardness

The tribological behavior of quench-tempered ductile iron (QTDI) and austempered ductile iron (ADI) with similar hardness was investigated. QTDI was composed of cementite particles, ferrite and spheroidal graphite, whilst ADI was consisted of acicular ferrite, retained austenite and spheroidal graphite. A higher yield strength was obtained for QTDI compared with ADI. Wear tests indicated that QTDI exhibited a lower friction coefficient than ADI. However, ADI had a better wear resistance than QTDI, which was because the transformation of re-sidual austenite into martensite induced by friction stress resulted in the increase of surface hardness. Worn surface morphology indicated that the main wear mechanisms of QTDI was adhesive and abrasive wear. How-ever, the surface fatigue wear was observed for ADI.