Additive manufacturing (AM) is a developing manufacturing technology, which provides excellent attributes compared to other manufacturing techniques. However, one of the critical challenges is the presence of defects that hinder the mechanical properties of the parts, particularly the fatigue life. Experimental understanding of fatigue is a cumbersome process. Therefore, numerical prediction based on specified conditions (such as porosity and applied load) can be an alternative to experimental analysis at the design stage of AM parts. In this study, elastic–plastic finite element analysis (FEA) is performed to obtain the stress distribution around pores, and their resultant effect on fatigue life for L-PBF (laser powder bed fusion) produced AlSi10Mg alloy samples. The stress field is calculated for both single and multiple pore models, where stress concentration is evaluated as a function of the pore’s location and its size. It is found that both pore location and size affect the stress field; however, location effects dominate over pore size. For the same remote applied stress level, the stress concentration around the pore increases with an increase in pore size, and the local maximum stress occurs near the pores that are closest to the surface. The current study also evaluates the relative effect of porosity fraction, average pore size, and location. It is found that the magnitude and sensitivity of stress concentration are hierarchically controlled by porosity location, pore size, and porosity density. A multi-scale finite element (FE) model is proposed based on inherent porosity data measured using Computed Tomography (CT) to predict overall fatigue life. The fatigue cycles are calculated using the rainflow counting algorithm in FE Safe using the stress–strain data obtained from the proposed FEA model. Using the proposed model, it is possible to generate S–N curves for any loading condition for a given porosity condition (porosity density and average pore size). The S–N curve results obtained from the FE model are compared to the experimental observations. The predicted fatigue life shows approximately 5% error with experimental results at high stress loading conditions. However, the proposed model overpredicts the fatigue life at low stress loading by almost 30%.

Fatigue and crack growth characteristics are essential cyclic properties of additively manufactured (AM) components for load-bearing applications, which are less reported in the literature than static properties. The fatigue behaviour of AM components is more complicated than those produced by conventional fabrication techniques (casting and forging) because of the multiplicity of different influencing factors like defect distribution, inhomogeneity of the microstructure and consequent anisotropy. Therefore, it is crucial to understand fatigue performance under different loading conditions to enhance AM application in aerospace, automotive, and other industries. The present work summarises the published literature for fatigue properties of popular metals (Ti–6Al–4V, Al–Si–Mg and stainless steels) produced by the laser powder-bed-fusion (L-PBF) process. Moreover, process parameters, post-processing treatments and microstructures of these alloys are discussed to evaluate the current state-of-the-art of fatigue and crack growth properties of L-PBF metals. The static properties of these alloys are also included to incorporate only those cases for which fatigue behaviour are discussed later in this review to make a correlation between the static and fatigue properties for these alloys. The effects of build orientation, microstructure, heat treatment, surface roughness and defects on fatigue strength and fatigue crack growth threshold are observed and critically analysed based on available literature. This study also highlights the common and contrary findings in the literature associated with various influential factors to comprehensively understand the cyclic loading behaviour of L-PBF produced metal alloys.