Fatigue Behavior of Additively Manufactured Inconel Alloys

Additive manufacturing (AM) of Inconel alloys, particularly Inconel 718, has ushered in new opportunities for producing high‐performance components with complex geometries for aerospace, energy and industrial applications. The unique thermal cycles inherent to processes such as laser powder bed fusion result in characteristic microstructures—often columnar grains, cellular substructures and segregation of strengthening phases—accompanied by residual stresses and porosity. These features profoundly influence fatigue life under both low‐ and high‐cycle regimes. Surface roughness, notches and process‐induced defects act as initiation sites for crack nucleation, while post‐processing treatments, notably heat treatment and hot isostatic pressing, alter precipitate distributions and residual stress states, enhancing damage tolerance. Build orientation introduces anisotropy in mechanical response, with fatigue performance varying between specimens loaded parallel or perpendicular to the layer direction. Current research integrates systematic defect engineering, multiscale characterisation and fatigue crack growth analyses to optimise process parameters and post‐treatments, with the ultimate aim of achieving fatigue properties comparable to or exceeding those of wrought counterparts.

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Fatigue Behavior of Additively Manufactured Inconel Alloys publication trend

The graph below shows the total number of articles in fatigue behavior of additively manufactured inconel alloys across all publications each year (not limited to Nature Index journals).

Technical terms

Additive manufacturing (AM): Layer-by-layer fabrication of components directly from digital models.

Laser powder bed fusion (LPBF): An AM technique using a laser to selectively melt metal powder in successive layers.

Porosity: Internal voids or defects within a material that can act as initiation sites for fatigue cracks.

Fatigue crack growth rate (FCGR): The speed at which a fatigue crack propagates under cyclic loading, often expressed as da/dN.

Functionally graded materials (FGMs): Structures with spatial variation in composition or microstructure to tailor local properties.

Build orientation: The direction in which layers are deposited relative to the loading axis, affecting anisotropy in properties.

References

1. Fatigue assessment of as‐built and heat‐treated Inconel 718 specimens produced by additive manufacturing including notch effects. Fatigue & Fracture of Engineering Materials & Structures (2020).
2. Shrink line impact on the fatigue resistance of Inconel 718 parts manufactured by powder bed fusion of metals using a laser beam. Journal of Manufacturing Processes (2024).
3. Intentionally seeding pores in additively manufactured alloy 718: Process parameters, microstructure, defects, and fatigue. Additive Manufacturing (2023).
4. Additive manufacturing of functionally graded inconel 718: Effect of heat treatment and building orientation on microstructure and fatigue behaviour. Journal of Materials Processing Technology (2022).