The failure modes of contact fatigue on austempered ductile iron have been researched. Ferrography technology has been applied to analyzing the procedure of contact fatigue. The tests show that the failure modes of contact fatigue on austempered ductile iron depend on the loading. In the case of heavy loading, the failure mode appears as spalling (the fatigue life is less than 5× 106cycles); whereas in the case of light loading, the failure mode appears as pitting. The fatigue creak initiates at the edge of...