Fatigue Prediction of Defective Additively Manufactured AlSi10Mg Alloy Based on Affected Depth

This work aims to predict the fatigue strength, based on the affected-depth approach, of the AlSi10Mg alloy obtained using additive manufacturing and containing artificial defects. Fatigue samples are produced in three directions: horizontal, vertical and 45°. The defect is modeled by a semi-spherical empty space at a surface specimen exposed to loading cycles. The finite element (FE) method is used to calculate the stresses surrounding the flaw. Given that plastic deformation develops near the defect, cyclic FE simulation is performed using an elastic-plastic model. The material’s mechanical behavior is characterized by a combined cyclic hardening law, which integrates isotropic hardening and nonlinear kinematic hardening components. The Crossland equivalent stress is calculated and plotted, starting from the base of the flaw and extending inward into the interior of the fatigue sample. The critical depth parameter is established through numerical analysis based on the experimental fatigue limit of a defect-containing specimen. The Kitagawa diagrams are generated by conducting iterative computations across various defect sizes, employing the affected-depth method. We construct Kitagawa diagrams in all three directions for both T6 heat-treated and unheated specimens. The modeled predictions correlate well with observed experimental outcomes. The findings clearly demonstrate that the presence of defects, the anisotropy of the microstructure and the application of T6 heat-treatment exert a significant influence on the fatigue life of the additively manufactured AlSi10Mg alloy. Utilizing Kitagawa–Takahashi diagrams enables engineers to address fatigue endurance problems by efficiently and safely calculating the fatigue lives of additively manufactured components with defects.