Title

Effect of pre-exposure on crack initiation life of a directionally solidified Ni-base superalloy

Authors

Authors

A. P. Gordon; R. W. Neu;D. L. McDowell

Comments

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Abstract

Blades and vanes are just two of several industrial gas turbine (IGT) components often subjected to long periods of elevated temperature before, during, and after high stress operating conditions. In these systems, cyclic loading is induced by repeated start-LIPS, firings, and shut-down ramps. Combinations of complex thermal and mechanical service conditions in the presence of aggressive reactants facilitate crack initiation via oxide spike formation. In the current study, the effect of pre-exposure on the oxide spiking damage mechanism and crack initiation life is characterized for a representative directionally solidified (DS) Ni-base superalloy, e.g. DS GTD-111. Comparisons of unexposed and pre-exposed samples reveal that 100 h of either creep pre-strain and/or thermal pre-exposure strongly influences the dominant damage mechanism that leads to crack initiation under subsequent fatigue cycling. A mechanistic model for crack initiation is modified to capture the influence of pre-exposure on life. (C) 2008 Elsevier Ltd. All rights reserved.

Journal Title

International Journal of Fatigue

Volume

31

Issue/Number

2

Publication Date

1-1-2009

Document Type

Article

First Page

393

Last Page

401

WOS Identifier

WOS:000266710600020

ISSN

0142-1123

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