Comparison of Fatigue Life and Strength Models for Defective Materials: Application to Scalmalloy in Different Surface Conditions

ABSTRACT Additive manufacturing (AM), particularly laser‐powder bed fusion (L‐PBF), has transformed the production of lightweight, high‐performance metallic components, with Scalmalloy emerging as a promising material due to its excellent strength‐to‐weight ratio, making it ideal for aerospace and automotive applications. However, process‐induced anomalies present challenges in achieving reliable fatigue performance, which requires robust methodologies for life prediction and defect‐tolerant design. This study investigates the fatigue behavior of L‐PBF Scalmalloy under various surface conditions (net‐shape and sandblasted) and orientations (vertical and inclined at 55°) using an advanced fracture mechanics framework. An experimental campaign evaluates fatigue strength under these varying conditions, with results compared between conventional models incorporating different assumptions regarding the long‐crack threshold (El‐Haddad model and NASGRO‐type equations) and R‐curve‐enhanced approaches. The analysis demonstrates the effectiveness of the R‐curve in improving fatigue predictions in all conditions tested, particularly in mitigating nonconservative results. This work advances the understanding of fatigue mechanisms in AM Scalmalloy, offering a framework for life prediction and defect‐tolerant design, ensuring more reliable applications of additively manufactured components in critical applications.