| Abstract: | In fatigue tests of plain carbon steel specimens in air, fatigue life is taken up mainly by the life in which a crack propagates from its initial size up to about 1 mm. This means that the behaviour of a small crack in the oil environment must be known in order to evaluate the effect of oils on fatigue life. In this paper, using a series of base oils of different viscosity grades, the effects of oils on fatigue damage are investigated in rotating bending fatigue tests of annealed 0.34% carbon steel plain specimens. Successive detailed observations of the specimen surface are made in order to study the fatigue processes of micro-crack initiation and small crack propagation. The physical background of the effect of oil environments on fatigue behaviour is shown, and a method for predicting fatigue life in oil environments is discussed. |
