High‐Cycle Fatigue Behavior of L‐PBF CoCrFeNi HEA Incorporating Effect of Stress Ratio

Stress ratio plays an important role in the fatigue behavior of additively manufactured alloys. In this paper, high‐cycle fatigue behavior of L‐PBF CoCrFeNi HEA incorporating effect of stress ratio is systematically investigated for the first time. With the increase of stress ratio, stress amplitude declines but maximum stress rises at the same number of loading cycles. Fatigue cracks mainly initiate from subsurface lack‐of‐fusion defects and are more prone to initiate at stress ratio of 0.5 rather than −1, −0.5, and 0.1. Fatigue crack propagation as well as grain refinement in crack propagation region is diminished with the increase of stress ratio. A modified Chaboche model incorporating effect of stress ratio was developed, which accurately predicts the high‐cycle fatigue life of L‐PBF CoCrFeNi HEA across all tested stress ratios and satisfactorily captures the associated scattering. This model can be adopted to well predict the fatigue life of other additively manufactured alloys.