High cycle fatigue behavior study and evaluation for GH3536 alloy fabricated by laser powder bed fusion

Additive manufacturing of nickel-based superalloys holds significant promise for applications in aero-engines and gas turbines. Evaluating the mechanical properties of these materials is crucial for facilitating their use in load-bearing components. This study investigates the high-cycle fatigue performance of the GH3536 alloy， which is fabricated via laser powder bed fusion and then undergoes solution heat treatment， with the assessment carried out at room temperature.By utilizing X-CT technology and performing fracture analysis， the defect characteristics of the material are comprehensively characterized. Furthermore， a quantitative analysis is conducted to explore the relationship between defect size and fatigue limit. The results reveal that the alloy contains porosity and lack-of-fusion defects， with surface and subsurface defects being the main contributors to fatigue fracture. The defect density in vertical samples is lower， leading to a slightly higher fatigue limit compared to that of horizontal samples.By using the effective defect size in the fracture source region of the fatigue sample， a more accurate and conservative prediction of the fatigue limit can be made. This is achieved by enhancing the Kitagawa-Takahashi （K-T） diagram with the El-Haddad model. The fatigue life of the alloy can be predicted by integrating this approach with the fatigue life characterization method based on the ratio proposed by Murakami， in combination with the El-Haddad model. This combined method provides higher prediction accuracy， especially for vertical samples with low defect density.