Artificial indentations for the study of contact fatigue of austempered ductile iron (ADI) discs

Following previous works in which artificial indentations were used to speed up surface damage in steel components [W. Cheng, H.S. Cheng, L.M. Keer, Experimental investigation on rolling/sliding contact fatigue crack initiation with artificial defects, Tribol. Trans. 37 (1994); H. Fan, L.M. Keer, W. Cheng, H.S. Cheng, Competition between fatigue crack propagation and wear, J. Tribol. 115 (1993); W. Cheng, H.S. Cheng, L.M. Keer, Longitudinal crack initiation under rolling contact fatigue, Tribol. Trans. 37 (1994); W. Cheng, H.S. Cheng, L.M. Keer, X. Ai, Surface crack initiation under contact fatigue: experimental observation and contact analysis, ASME Trans. 115 (1993)], twin-disc tests were performed using artificially indented austempered ductile iron (ADI) discs. These tests were closely monitored and included detailed video microscopy observation of contacting surfaces and indentations neighbourhood. Post-test analysis included optical and scanning electronic microscopy of surfaces, sub-surfaces and indentations.