Anisotropic fatigue properties of Alloy 718 manufactured by Electron Beam Powder Bed Fusion

Arun Ramanathan Balachandramurthi,Johan Moverare,Thomas Hansson,Robert Pederson

doi:10.1016/j.ijfatigue.2020.105898

Arun Ramanathan Balachandramurthi, Johan Moverare + Show 2 more

Open Access

https://doi.org/10.1016/j.ijfatigue.2020.105898

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Abstract

In this study, Alloy 718 specimens manufactured by Electron Beam Powder Bed Fusion process are subjected to two different post-treatments to have different microstructural features. Low cycle fatigue testing has been performed both parallel and transverse to the build direction. EB-PBF Alloy 718 exhibits anisotropic fatigue behaviour; the fatigue life is better along the parallel direction compared to the transverse direction. The anisotropy in fatigue life is related to the anisotropy in the Young's modulus. The pseudo-elastic stress vs. fatigue life approach is presented as a potential solution to handle anisotropy in fatigue life assessment of additively manufactured engineering components.

Highlights

The interest in additive manufacturing (AM) of metals has consistently grown among both industrial and academic research groups across the world in the last decade
Gas porosity (< 50 μm) were distributed randomly throughout the microstructure. All these microstructural features are consistent with reported literature on EBPBF processing of Alloy 718 [14,35]
low cycle fatigue (LCF) properties of Alloy 718 manufactured by EB-powder bed fusion (PBF) process and subjected to two different post-treatments have been investigated

Summary

Introduction

The interest in additive manufacturing (AM) of metals has consistently grown among both industrial and academic research groups across the world in the last decade. Metal AM technology is still maturing and evolving, yet the high interest is primarily due to design related advantages offered by AM for the low-volume-sector. AM is poised to expand rapidly in the aviation industry, with applications such as new parts and repairs [1]. While the design advantages of AM are obvious, the mechanical behaviour and performance of the AM material need to be characterized and understood in depth, in relation to the microstructure, before AM parts could be used extensively in critical applications. With increasing part complexity and criticality of AM parts there is an urgent need in a thorough understanding of the fatigue properties. It is imperative considering that more than half of all the failures in aircraft components have been fatigue related [3]

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