Mechanistic behaviour and modelling of creep in powder metallurgy FGH96 nickel superalloy
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
The creep properties of a nickel-based superalloy at 700 °C and 690 MPa resulting from differing aging heat treatments have been investigated. The heat treatments gave rise to significantly different tertiary γ′ precipitate distributions which in turn influence the propensity for precipitate shearing. The creep life was found to decrease with an increase of volume fraction of tertiary γ′. It is shown that the γ′ precipitates undergo shearing by matrix dislocations resulting in residual stacking faults which have been identified from TEM studies.
A physically-based crystal slip model for creep deformation in FGH96 has been developed. A critical γ′ precipitate size is found to exist above which precipitate shearing occurs by strongly-coupled dislocations pairs. The critical size for FGH96 superalloy is less than 15 nm, which is smaller than most of the γ′ precipitates in the aged treated samples. A bimodal precipitate hardening model has been presented from which the slip strength resulting from differing heat treatments may be determined. Creep strain rate is found to decrease with increasing slip strength. The crystal slip model successfully captures the effect of heat treatment (in terms of γ′ precipitate distributions) on resulting creep behaviour in alloy FGH96.
A physically-based crystal slip model for creep deformation in FGH96 has been developed. A critical γ′ precipitate size is found to exist above which precipitate shearing occurs by strongly-coupled dislocations pairs. The critical size for FGH96 superalloy is less than 15 nm, which is smaller than most of the γ′ precipitates in the aged treated samples. A bimodal precipitate hardening model has been presented from which the slip strength resulting from differing heat treatments may be determined. Creep strain rate is found to decrease with increasing slip strength. The crystal slip model successfully captures the effect of heat treatment (in terms of γ′ precipitate distributions) on resulting creep behaviour in alloy FGH96.
Date Issued
2016-09-01
Date Acceptance
2016-08-26
Citation
Materials Science and Engineering A, 2016, 676, pp.441-449
ISSN
0921-5093
Publisher
Elsevier
Start Page
441
End Page
449
Journal / Book Title
Materials Science and Engineering A
Volume
676
Copyright Statement
© 2016 Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Beijing Institute of Aeronautical Materials (BIAM)
Royal Academy Of Engineering
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000384853000051&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
N/A
MMRE_P54661
Subjects
Science & Technology
Technology
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Metallurgy & Metallurgical Engineering
Science & Technology - Other Topics
Materials Science
PM FGH96 superalloy
Precipitation hardening
Creep modelling
Materials
0912 Materials Engineering
0913 Mechanical Engineering
Publication Status
Published