Fracture process in high-temperature fatigue of Ni-based single crystal superalloy CMSX-10 and effect of removal of surface oxide-layer on crack initiation

Naoya Tada, R. Ohtani, M. Shibata, T. Kobayashi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Fatigue tests were conducted at 1273K using smooth bar specimens of a nickel-based single crystal superalloy CMSX-10, and small cracks were observed on the surface of the specimens by means of microscope. It was clarified by the observation that fatigue fracture of CMSX-10 takes place as follows; (1) Oxide-layer was formed on the surface of the specimen. (2) A lot of small cracks of the size of about 100μm were initiated perpendicular to the stress axis on the surface of the oxide-layer. (3) Some of them grew and penetrated the oxide-layer to reach the base metal. Processes (1) to (3) were completed at the very early stage of fatigue life. (4) Growth of the cracks that reached the base metal brought about the final fracture. As the formation of oxide-layer on the surface of the specimen was considered to be a trigger of crack initiation, a fatigue test was also conducted with repeated removal of the oxide-layer by emery paper and diamond paste. In this test, no crack appeared on the surface of the specimen even at 20000 cycles when a lot of cracks were observed in the normal fatigue tests. This proves that removal of the oxide-layer retards the initiation of small cracks and extends the fatigue life.

Original languageEnglish
Pages (from-to)129-136
Number of pages8
JournalZairyo/Journal of the Society of Materials Science, Japan
Volume50
Issue number2
Publication statusPublished - Feb 2001

Fingerprint

thermal fatigue
crack initiation
heat resistant alloys
Superalloys
Crack initiation
Oxides
cracks
Single crystals
Fatigue of materials
Cracks
fatigue tests
oxides
single crystals
fatigue life
Temperature
Metals
Diamond
Ointments
Nickel
metals

Keywords

  • CMSX-10
  • High-temperature fatigue
  • Nickel-based superalloy
  • Oxide-layer
  • Single crystal
  • Small cracks

ASJC Scopus subject areas

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

Cite this

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title = "Fracture process in high-temperature fatigue of Ni-based single crystal superalloy CMSX-10 and effect of removal of surface oxide-layer on crack initiation",
abstract = "Fatigue tests were conducted at 1273K using smooth bar specimens of a nickel-based single crystal superalloy CMSX-10, and small cracks were observed on the surface of the specimens by means of microscope. It was clarified by the observation that fatigue fracture of CMSX-10 takes place as follows; (1) Oxide-layer was formed on the surface of the specimen. (2) A lot of small cracks of the size of about 100μm were initiated perpendicular to the stress axis on the surface of the oxide-layer. (3) Some of them grew and penetrated the oxide-layer to reach the base metal. Processes (1) to (3) were completed at the very early stage of fatigue life. (4) Growth of the cracks that reached the base metal brought about the final fracture. As the formation of oxide-layer on the surface of the specimen was considered to be a trigger of crack initiation, a fatigue test was also conducted with repeated removal of the oxide-layer by emery paper and diamond paste. In this test, no crack appeared on the surface of the specimen even at 20000 cycles when a lot of cracks were observed in the normal fatigue tests. This proves that removal of the oxide-layer retards the initiation of small cracks and extends the fatigue life.",
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T1 - Fracture process in high-temperature fatigue of Ni-based single crystal superalloy CMSX-10 and effect of removal of surface oxide-layer on crack initiation

AU - Tada, Naoya

AU - Ohtani, R.

AU - Shibata, M.

AU - Kobayashi, T.

PY - 2001/2

Y1 - 2001/2

N2 - Fatigue tests were conducted at 1273K using smooth bar specimens of a nickel-based single crystal superalloy CMSX-10, and small cracks were observed on the surface of the specimens by means of microscope. It was clarified by the observation that fatigue fracture of CMSX-10 takes place as follows; (1) Oxide-layer was formed on the surface of the specimen. (2) A lot of small cracks of the size of about 100μm were initiated perpendicular to the stress axis on the surface of the oxide-layer. (3) Some of them grew and penetrated the oxide-layer to reach the base metal. Processes (1) to (3) were completed at the very early stage of fatigue life. (4) Growth of the cracks that reached the base metal brought about the final fracture. As the formation of oxide-layer on the surface of the specimen was considered to be a trigger of crack initiation, a fatigue test was also conducted with repeated removal of the oxide-layer by emery paper and diamond paste. In this test, no crack appeared on the surface of the specimen even at 20000 cycles when a lot of cracks were observed in the normal fatigue tests. This proves that removal of the oxide-layer retards the initiation of small cracks and extends the fatigue life.

AB - Fatigue tests were conducted at 1273K using smooth bar specimens of a nickel-based single crystal superalloy CMSX-10, and small cracks were observed on the surface of the specimens by means of microscope. It was clarified by the observation that fatigue fracture of CMSX-10 takes place as follows; (1) Oxide-layer was formed on the surface of the specimen. (2) A lot of small cracks of the size of about 100μm were initiated perpendicular to the stress axis on the surface of the oxide-layer. (3) Some of them grew and penetrated the oxide-layer to reach the base metal. Processes (1) to (3) were completed at the very early stage of fatigue life. (4) Growth of the cracks that reached the base metal brought about the final fracture. As the formation of oxide-layer on the surface of the specimen was considered to be a trigger of crack initiation, a fatigue test was also conducted with repeated removal of the oxide-layer by emery paper and diamond paste. In this test, no crack appeared on the surface of the specimen even at 20000 cycles when a lot of cracks were observed in the normal fatigue tests. This proves that removal of the oxide-layer retards the initiation of small cracks and extends the fatigue life.

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