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International journal of fatigue 160, 106824 (2022). doi:10.1016/j.ijfatigue.2022.106824, Published by Elsevier, Oxford

Generalization of microstructural short crack (MSC) growth simulation across different loading conditions and materials is often not considered in literature. These points are addressed by transferring a previously proposed model for crack initiation and transgranular MSC growth from ferritic steel to the martensitic steel SAE 4150. An accurate depiction of the microstructure is achieved by a novel approach to parameterize martensitic tessellations. Calculated fatigue lifetimes are in similarly good agreement with experimental data for martensite as for previously considered ferrite. The model’s transferability is shown among distinct load ratios and between strain- and stress-controlled loading, subject only to small deviations.

Microstructural short crack (MSC) growth profoundly influences the fatigue lifetime of steels. For finite element simulations with crystal plasticity, a MSC model for industrial application is described for the ferritic steel EN 1.4003. As transgranular cracking is dominant in the early fatigue stages for this material, intergranular crack growth is excluded. Crack data from micro fatigue specimen is used to validate simulated crack paths. With a manual prescription of the crack initiation site, a substantial agreement between the predicted and experimental crack paths is revealed. Using an appropriate calibration strategy for the parametrization of the MSC model, the feasibility for lifetime prediction is also shown.