Crack nucleation using combined crystal plasticity modelling, HR-DIC and HR-EBSD in a superalloy containing non-metallic inclusions under fatigue

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Title: Crack nucleation using combined crystal plasticity modelling, HR-DIC and HR-EBSD in a superalloy containing non-metallic inclusions under fatigue
Author(s): Zhang, T
Jiang, J
Britton, TB
Shollock, B
Dunne, F
Item Type: Journal Article
Abstract: A crystal plasticity finite element (CPFE) model which explicitly and directly represents the complex microstructures of a non-metallic agglomerate inclusion within polycrystal nickel alloy has been developed to study the mechanistic basis of fatigue crack nucleation. The methodology is to utilise the CP model in conjunction with direct measurement at the microscale using high (angular) resolution electron backscatter diffraction (HR-EBSD) and high (spatial) resolution digital image correlation (HR-DIC) strain measurement techniques. Experimentally, this sample has been subjected to heat treatment leading to the establishment of residual (elastic) strains local to the agglomerate and subsequently loaded under conditions of low cyclic fatigue. The full thermal and mechanical loading history was reproduced within the model. HR-EBSD and HR-DIC elastic and total strain measurements demonstrate qualitative and quantitative agreement with crystal plasticity results. Crack nucleation by interfacial decohesion at the nickel matrix/agglomerate inclusion boundaries is observed experimentally, and systematic modelling studies enable the mechanistic basis of the nucleation to be established. A number of fatigue crack nucleation indicators are also assessed against the experimental results. Decohesion was found to be driven by interface tensile normal stress alone and the interfacial strength was determined to be in the range of 1270-1480 MPa.
Date of Acceptance: 11-Mar-2016
URI: http://hdl.handle.net/10044/1/32247
ISSN: 1364-5021
Publisher: Royal Society, The
Journal / Book Title: Proceedings of the Royal Society A: Mathematical, Physical & Engineering Sciences
Sponsor/Funder: Royal Academy Of Engineering
Royal Academy Of Engineering
Funder's Grant Number: RF/129
MMRE_P54661
Keywords: 01 Mathematical Sciences
02 Physical Sciences
09 Engineering
Publication Status: Accepted
Appears in Collections:Faculty of Engineering
Materials



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