The effect of thermomechanical processing on the creep behavior of Alloy 690

Research output: Contribution to journalArticle

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Abstract

The effect of thermomechanical processing on the microstructure and elevated-temperature creep behavior of Alloy 690 was investigated. Commercially available sheet was subjected to four cycles of cold rolling to 25% deformation followed by annealing at 1000 °C for 1 h. Both the resultant microstructure and the original microstructure were characterized using electron backscattered diffraction. The thermomechanically processed microstructure exhibited a slightly lower fraction of twins and a smaller average grain size than the original microstructure. Tensile-creep experiments were performed in an open-air environment at temperatures between 650 and 690 °C and stresses between 75 and 172 MPa. The measured creep stress exponents (4-5) activation energies (320-368 kJ/mol) suggested that dislocation creep with lattice self-diffusion was dominant. The thermomechanically processed microstructure exhibited significantly worse creep resistance than the original as-processed microstructure. Thus, cyclic strain and annealing processing, which has been shown to improve the ductility-dip cracking susceptibility of Alloy 690, is not recommended for enhancing the creep resistance.

LanguageEnglish (US)
Pages233-237
Number of pages5
JournalMaterials Science and Engineering A
Volume473
Issue number1-2
DOIs
StatePublished - Jan 25 2008

Profile

Creep
microstructure
Microstructure
Processing
creep strength
Creep resistance
tensile creep
Annealing
cold rolling
annealing
Cold rolling
ductility
Electron diffraction
Ductility
electron diffraction
Activation energy
grain size
exponents
activation energy
magnetic permeability

Keywords

  • Creep
  • Electron backscattered diffraction
  • Microstructure
  • Nickel-based alloy

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

The effect of thermomechanical processing on the creep behavior of Alloy 690. / Boehlert, C. J.

In: Materials Science and Engineering A, Vol. 473, No. 1-2, 25.01.2008, p. 233-237.

Research output: Contribution to journalArticle

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abstract = "The effect of thermomechanical processing on the microstructure and elevated-temperature creep behavior of Alloy 690 was investigated. Commercially available sheet was subjected to four cycles of cold rolling to 25{\%} deformation followed by annealing at 1000 °C for 1 h. Both the resultant microstructure and the original microstructure were characterized using electron backscattered diffraction. The thermomechanically processed microstructure exhibited a slightly lower fraction of twins and a smaller average grain size than the original microstructure. Tensile-creep experiments were performed in an open-air environment at temperatures between 650 and 690 °C and stresses between 75 and 172 MPa. The measured creep stress exponents (4-5) activation energies (320-368 kJ/mol) suggested that dislocation creep with lattice self-diffusion was dominant. The thermomechanically processed microstructure exhibited significantly worse creep resistance than the original as-processed microstructure. Thus, cyclic strain and annealing processing, which has been shown to improve the ductility-dip cracking susceptibility of Alloy 690, is not recommended for enhancing the creep resistance.",
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