Enhanced Weibull Formulation for Capturing Fatigue Life Scatter in AM Alloys Supported by Fractographic Analysis

The fatigue performance of components produced via selective laser melting technology is strongly influenced by several factors as printing process parameters, build orientation and internal defects. This study investigates the fatigue behavior of AlSi10Mg specimens with machined surfaces, emphasizing the unusually high variability in lifetimes observed in samples built in the Z direction. A refined Weibull statistical approach, accounting for defect-induced scatter and supported by fractographic analysis, is proposed. The novel bimodal probabilistic framework, calibrated through maximum likelihood estimation method, distinguishes between two dominant defect types—porosity and lack of fusion—enabling a more accurate description of fatigue life distributions. The model successfully captures defect-specific fatigue limits and offers a robust method for integrating defect morphology into lifetime predictions, with strong implications for engineering design and reliability assessment of additively manufactured components.