Fatigue behaviour of laser powder bed fusion (L-PBF) Ti–6Al–4V, Al–Si–Mg and stainless steels: a brief overview

Abstract

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.

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“…Build orientation, microstructure, and post-build treatment and surface finish can affect material behavior. The two major factors that lower the performance and life of additively manufactured metal structures are surface roughness and subsurface pores (Afroz et al 2022; Segersall et al 2021). Surface-connected porosities are often points of crack initiation and cracks that propagate from the surface into the material can lead to fatal structural failure.…”