Experimental observations of contact fatigue crack mechanisms for austempered ductile iron (ADI) discs

Collected from several twin-disc contact fatigue tests, images concerning c rack development at ADI surfaces and sub-surfaces are presented. Several au xiliary surface analysis techniques were used (electronic scanning microsco py, video imaging and perfilometry). Defects found at these ADI samples are characterised and related to operating conditions. Elastohydrodinamic theo ry was used to evaluate surface tribological performance, involving paramet ers such as lubrication, roughness and general operating conditions. Results concerning a quick procedure to allow the evaluation of fatigue res istance properties among different ADI sample discs are also presented. (C) 2000 Elsevier Science S.A. All rights reserved.