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For a proper estimation of the fatigue life of a heavy-walled cast component made of nodular cast iron, sufficient knowledge regarding the cyclic properties of the material is necessary. Based on the material parameters at hand for component design, different fatigue analysis procedures can be used. Elastic and elastic-plastic approaches can be adopted, with the latter being reserved only for local approaches. The present publication summarizes the cyclic material parameters gained during a research project by extensive material tests under stress and strain controlled cyclic loading at different load ratios for three nodular cast iron grades. In addition to an improved knowledge of the cyclic material behavior, the notch, the size effects and the mean stress sensitivity were of special concern during the investigations in order to provide an entire overview of the tested materials and thus input information for both stress and strain based design approaches. Tests were performed for specimens taken from large cast blocks of the nodular cast iron grades EN-GJS-400-18U-LT and EN-GJS-450-18, both with ferritic matrices, and EN-GJS-700-2 with a pearlitic matrix. For some of these materials, mean stress sensitivities above 0.5 were obtained during the investigations. These values are not covered by the common standards, which calculate lower values for the mean stress sensitivity. Cyclic material parameters for stress and strain controlled tests are given in this paper as well as values for the size effect, based on the concept of the highly stressed volume. The effect of different specimen sizes could be shown not only by stress but also by strain controlled tests.

The consideration of realistic load assumptions is important for the fatigue design of highly stressed nodular cast iron components for wind energy application. Especially in case of overloads causing elastic–plastic deformation, residual stresses may have a strong impact on fatigue life. In strain‐controlled fatigue tests with constant and variable amplitudes, the influence of overloads on lifetime was investigated. During fatigue testing, the transient material behavior, cyclic hardening, cyclic relaxation of the residual stresses, and quasi‐static creep effects of the EN‐GJS‐400‐18‐LT was recorded and evaluated. To quantify the influence of the transient material behavior on the calculated lifetime, fatigue analyses are carried out with the strain‐life approach, both with and without consideration of the transient material behavior. The results show that conservative damage sums are derived if the transient material behavior, especially the relaxation of tensile residual stresses, is neglected.

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