Fatigue crack growth in IN718/316L multi-materials layered structures fabricated by laser powder bed fusion

M.S.Duval-Chaneac^abN.Gao^aR.H.U.Khan^cM.Giles^aK.Georgilas^bX.Zhao^aP.A.S.Reed^a

Materials Research Group, Faculty of Engineering and Physical Sciences, University of Southampton

^b

NSIRC, TWI Ltd. Cambridge

^c

TWI Ltd., Cambridge

International Journal of Fatigue

Volume 152, November 2021, 106454 Available online 30 July 2021.

https://doi.org/10.1016/j.ijfatigue.2021.106454

Highlights

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Layered specimen of 316L and IN718 has been fabricated by multiple material additive manufacturing.

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The crack propagation mechanism was investigated under three point bending, and recorded via direct current potential drop method, then analysed via correlation between the stress intensity factor and the final fracture surface.

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Mechanisms of shielding and antishielding in the crack propagation were investigated through a 4 alternated layer specimen.

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Relation between the as-built microstructure and the tensile properties of each alloy was used to put in perspective the results obtained in the different crack propagation tests.

Abstract

Multi-materials additive manufacturing (MMAM) allows the functional optimisation of components by tailoring the addition of alloys at different design locations in a single operation. In this study Laser Powder Bed Fusion (L-PBF) technique was used to manufacture layered specimens combining IN718 and 316L materials. The microstructure and mechanical properties were studied by scanning electron microscopy (SEM), tensile, micro and nanohardness testing. The fatigue tests were performed to determine the crack propagation process through multi-layer specimens in the as-built (AB) state.

Keywords

Multi-materials

Additive manufacturing (AM)

Interface

Fatigue analysis

Crack growth rate