An analysis of gear wear and micro-pitting evolution during contact fatigue

Abstract This work uses contact fatigue tests to study the wear and micro-pitting evolution on gear teeth. The study reveals a competitive relationship between wear and micro-pitting corrosion in gear contact fatigue. Experimental results demonstrate that micro-pitting initially appears at the root of the carburized and quenched gear teeth and gradually spreads across the entire tooth width during the running-in process. As micro-pitting occurs, the oil film thickness is continuously reduced, leading to the emergence of wear. Micro-pitting and wear coexist and develop competitively, but as the number of cycles reaches 16 million, wear causes the tiny pits on the tooth’s surface to vanish as the wear rate exceeds the expansion rate of micro-pitting. Both micro-pitting and wear alter the tooth surface morphology and profile in distinct manners.