Influence of Water on Fatigue-Failure Location and Surface Alteration During Rolling-Contact Lubrication

Abstract

The influence of dissolved water in the lubricant on fatigue-failure location and surface alteration was determined from experiments conducted with a planetary four-ball machine in the range of 925 to 1300 ksi maximum Hertz compressive stress. The distribution of fatigue spalls on the bearing ball surfaces was influenced by small amounts of water in the hydrocarbon lubricant. In the presence of 0.01 precent water an increase in fatigue-failures occurred on the chemically more reactive portion of the bearing balls. An increase in wear during rolling contact was observed due to the presence of water. This was demonstrated by weight determinations, surface profile measurements and light microscopy.