Estimation methods for fatigue properties of steels under axial and torsional loading

Uniaxial and torsional fatigue tests have been conducted on eight steels. The cyclic equivalent stress and strain amplitudes can be fitted by the Ramberg-Osgood relationship. Fatigue lives are found correlated with the equivalent strain amplitude. Seven methods for estimating uniaxial fatigue properties from tensile properties or hardness have been evaluated. The modified universal slopes method by Muralidharan and Manson, the uniform material law by Bäumel and Seeger and the hardness method by Roessle and Fatemi predicted over 93% of test cases within the factor of 3 compared with observed lives. These methods are also found applicable to torsional fatigue with fatigue properties estimated from uniaxial fatigue properties based on the equivalent strain criterion.