Fatigue tests were conducted on smooth specimens of low carbon steel under rotating bending and torsion in air, in distilled water and in 3% salt water, and the crack length distributions for the fixed cycle ratios were examined. The crack length was found to be arranged by the Weibull distribution under both loading conditions and three environments. Moreover, the dependence of shape parameter of the weibull distribution on stress levels and cycle ratios showed different behaviours in each environment. This seemed to be caused by the difference in crack propagation behaviours.
