Cyclic shear response of additively manufactured Inconel 718
ISSN: 1355-2546
Article publication date: 18 June 2020
Issue publication date: 23 July 2020
Abstract
Purpose
Additive manufacturing (AM) studies on Inconel 718 (IN718) have focused on exploring its tensile and fatigue response. As IN718 is used in the propulsion and energy sector, the impact of shearing is also critical to ensuring the durability of these components. As such, this study aims to explore the relation between build orientation on the shear cyclic response of direct metal laser sintered (DMLS) IN718.
Design/methodology/approach
IN718 torsion specimens were manufactured along six build orientations: (100)-X, (010)-Y, (001)-Z, (110)-XY45, (101)-XZ45 and (011)-YZ45, using the DMLS process. Torsional fatigue testing was performed on as-built specimens, from which fracture behavior, surface roughness, softening/hardening response and monotonic/cyclic shear torsional properties were assessed.
Findings
DMLS IN718 was found to exhibit transversely isotropic behavior. In terms of shear stress range and shear modulus, Z > (X, XY45, Y) > (XZ45, YZ45). Specimens cyclically hardened to stabilization and softened to fracture. In terms of torsional fatigue fracture response, the Z, XZ45 and YZ45 specimens exhibited crack initiation and propagation from internal defects, whereas cracks were found to initiate at the surface and propagate between and through build layers for the X, Y and XY45 specimens.
Originality/value
This study reports the torsional cyclic response and shear moduli exhibited by as-built DMLS IN718 manufactured along varying build orientations. The findings are applicable for researchers because of the wide use of IN718 in the gas turbine industry, and the current trend to replace conventional manufacturing with AM.
Keywords
Acknowledgements
This work is supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. (1144246) awarded to Sanna F. Siddiqui. The authors would like to thank Dr. Robert Peale and Seth Calhoun, for use of the Veeco Dektak3ST profilometer in the Micro Device Prototyping Facility for surface roughness measurements.
Citation
Siddiqui, S.F. and Gordon, A.P. (2020), "Cyclic shear response of additively manufactured Inconel 718", Rapid Prototyping Journal, Vol. 26 No. 7, pp. 1237-1248. https://doi.org/10.1108/RPJ-09-2018-0243
Publisher
:Emerald Publishing Limited
Copyright © 2020, Emerald Publishing Limited