The effects of environment and dwell on high temperature fatigue crack growth of 2 1/4 Cr - 1 Mo steel.
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Authors
Kamen, John S.
Subjects
2 1/4 Cr - ] Mo Steel
creep-fatigue interaction
high temperature fatigue crack growth
environment effects on fatigue crack growth
oxidation effects on fatigue crack growth
creep-fatigue interaction
high temperature fatigue crack growth
environment effects on fatigue crack growth
oxidation effects on fatigue crack growth
Advisors
Challenger, K.D.
Date of Issue
1983-06
Date
June 1983
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The effects of the environment and dwell periods on
fatigue crack growth rates at 525°C for both annealed and
normalized and tempered 2 1/4 Cr - 1 Mo steel in High
Strain Fatigue (HSF) and Linear Elastic Fracture Mechanics
(LEFM) regimes in air and in vacuum have been examined
using optical and scanning electron microscopy techniques.
Fatigue crack propagation rates were determined and were
found to vary with the environment and the loading waveform
used in the tests. At small crack depths in HSF, oxidation
in air increased cyclic crack growth rates by over an order
of magnitude compared with vacuum. For continuous cycling
tests at a frequency of 0.01 Hz, and tests with a peak
tension, compression, or tension plus compression dwell
cycling, the rates were similar. The fastest crack growth
in air occurred during cycles having both tension and
compression dwell periods. Fractographs were analyzed in
attempts to understand the reasons for the different propagation
rates. Evidence suggesting partial rewelding of the
crack surfaces during compressive dwell periods in vacuum
and a change in fracture mode from transgranular to a
branching "intergranular-like" fracture when the environment
was changed from air to vacuum were observed.
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.