Mechanism of crack initiation induced by oxide-layer cracking in high-temperature fatigue of the nickel base single crystal superalloy CMSX-2

Naoya Tada, Ryuichi Ohtani, Atsuhide Wada

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Fatigue tests were conducted at 1273K using smooth bar specimens of the first-generation nickel-base single crystal superalloy CMSX-2. Oxide-layer on the surface of the specimen and the base metal were carefully observed by means of scanning electron microscope after the tests. It was clarified by the observation that crack initiation in high-temperature fatigue of CMSX-2 was mainly brought about by cracking of the oxide-layer which was formed on the surface of the specimen. Comparing the results obtained from the tests with different stress and strain waveforms, cracking of the oxide-layer found to be easily occurred when the following two conditions are satisfied. The first one is sufficient time for the formation of oxide-layer since cracking occurred in thick oxide-layer and the crack continued to grow inside the base metal. The second condition is that there is tensile-going strain after the formation of oxide-layer. The brittle oxide-layer was easily cracked by the following tensile loading. Moreover, there observed change in γ/γ′-structure during the fatigue test and this structural change brought the decrease in cyclic deformation resistance. This might have quickened the oxide-layer cracking particularly in stress-controlled condition.

Original languageEnglish
Pages (from-to)132-138
Number of pages7
JournalZairyo/Journal of the Society of Materials Science, Japan
Volume52
Issue number2
Publication statusPublished - Feb 2003

Fingerprint

thermal fatigue
crack initiation
heat resistant alloys
Nickel
Superalloys
Crack initiation
Oxides
Single crystals
nickel
Fatigue of materials
oxides
single crystals
Temperature
fatigue tests
Metals
Tensile strain
metals
waveforms
Electron microscopes
cracks

Keywords

  • CMSX-2
  • Crack
  • High-temperature fatigue
  • Nickel-base superalloy
  • Oxide-layer
  • Single crystal

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Metals and Alloys
  • Polymers and Plastics

Cite this

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title = "Mechanism of crack initiation induced by oxide-layer cracking in high-temperature fatigue of the nickel base single crystal superalloy CMSX-2",
abstract = "Fatigue tests were conducted at 1273K using smooth bar specimens of the first-generation nickel-base single crystal superalloy CMSX-2. Oxide-layer on the surface of the specimen and the base metal were carefully observed by means of scanning electron microscope after the tests. It was clarified by the observation that crack initiation in high-temperature fatigue of CMSX-2 was mainly brought about by cracking of the oxide-layer which was formed on the surface of the specimen. Comparing the results obtained from the tests with different stress and strain waveforms, cracking of the oxide-layer found to be easily occurred when the following two conditions are satisfied. The first one is sufficient time for the formation of oxide-layer since cracking occurred in thick oxide-layer and the crack continued to grow inside the base metal. The second condition is that there is tensile-going strain after the formation of oxide-layer. The brittle oxide-layer was easily cracked by the following tensile loading. Moreover, there observed change in γ/γ′-structure during the fatigue test and this structural change brought the decrease in cyclic deformation resistance. This might have quickened the oxide-layer cracking particularly in stress-controlled condition.",
keywords = "CMSX-2, Crack, High-temperature fatigue, Nickel-base superalloy, Oxide-layer, Single crystal",
author = "Naoya Tada and Ryuichi Ohtani and Atsuhide Wada",
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T1 - Mechanism of crack initiation induced by oxide-layer cracking in high-temperature fatigue of the nickel base single crystal superalloy CMSX-2

AU - Tada, Naoya

AU - Ohtani, Ryuichi

AU - Wada, Atsuhide

PY - 2003/2

Y1 - 2003/2

N2 - Fatigue tests were conducted at 1273K using smooth bar specimens of the first-generation nickel-base single crystal superalloy CMSX-2. Oxide-layer on the surface of the specimen and the base metal were carefully observed by means of scanning electron microscope after the tests. It was clarified by the observation that crack initiation in high-temperature fatigue of CMSX-2 was mainly brought about by cracking of the oxide-layer which was formed on the surface of the specimen. Comparing the results obtained from the tests with different stress and strain waveforms, cracking of the oxide-layer found to be easily occurred when the following two conditions are satisfied. The first one is sufficient time for the formation of oxide-layer since cracking occurred in thick oxide-layer and the crack continued to grow inside the base metal. The second condition is that there is tensile-going strain after the formation of oxide-layer. The brittle oxide-layer was easily cracked by the following tensile loading. Moreover, there observed change in γ/γ′-structure during the fatigue test and this structural change brought the decrease in cyclic deformation resistance. This might have quickened the oxide-layer cracking particularly in stress-controlled condition.

AB - Fatigue tests were conducted at 1273K using smooth bar specimens of the first-generation nickel-base single crystal superalloy CMSX-2. Oxide-layer on the surface of the specimen and the base metal were carefully observed by means of scanning electron microscope after the tests. It was clarified by the observation that crack initiation in high-temperature fatigue of CMSX-2 was mainly brought about by cracking of the oxide-layer which was formed on the surface of the specimen. Comparing the results obtained from the tests with different stress and strain waveforms, cracking of the oxide-layer found to be easily occurred when the following two conditions are satisfied. The first one is sufficient time for the formation of oxide-layer since cracking occurred in thick oxide-layer and the crack continued to grow inside the base metal. The second condition is that there is tensile-going strain after the formation of oxide-layer. The brittle oxide-layer was easily cracked by the following tensile loading. Moreover, there observed change in γ/γ′-structure during the fatigue test and this structural change brought the decrease in cyclic deformation resistance. This might have quickened the oxide-layer cracking particularly in stress-controlled condition.

KW - CMSX-2

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KW - Nickel-base superalloy

KW - Oxide-layer

KW - Single crystal

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