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Effect of crack orientation on fracture behaviour of Wire + Arc Additively Manufactured (WAAM) nickel-base superalloy

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Original languageEnglish
Title of host publicationProceedings of the ASME 2018 Pressure Vessels and Piping Conference
DatePublished - 2018

Abstract

In this study, the effect of crack orientation on the fracture
behaviour of two compact tension C(T) specimens extracted
from a Wire + Arc Additively Manufactured (WAAM) wall made
from Inconel (IN) 625 nickel-base superalloy was investigated.
Both specimens had different levels of ductile tearing but their
load vs. crack mouth opening displacement (CMOD) behaviour
was relatively similar. The total-and-elastic strain distribution
around a crack tip was measured in both specimens using Digital
Image Correlation (DIC) and neutron diffraction respectively.
The results show that the strain distribution and deformation
around the crack tip are different in the two directions. In the
specimen with crack orientation parallel to the build direction,
banding was observed in both the total strain maps and the
deformation pattern. Neutron diffraction measurements on this
specimen also showed non-monotonic elastic strain evolution,
suggesting the occurrence of intergranular load shedding
mechanisms. These were not observed in the specimen with
crack orientation perpendicular to the build direction. Electron
Backscatter Diffraction (EBSD) maps show that the WAAM
IN625 material is strongly textured with coarse columnar grains
elongated in the build direction. The effect of microstructure has
been correlated with the differences in strain distribution in the
two specimens.

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