The effect of d0 reference value on a neutron diffraction study of residual stress in a γ/γ' nickel-base superalloy

James Rolph, Naveed Iqbal, Michael Hoffman, Alex Evans, Mark C. Hardy, Michael G. Glavicic, Michael Preuss

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

A nickel-base superalloy sub-scale disc has been studied using neutron diffraction to characterise the residual stress distribution following heat treatment. Strain has been calculated using measured neutron diffraction d-spacings in combination with d0 reference values obtained using three distinct methods, namely, measurement of a stress-free cube, a sin2c characterisation (used independently and as a correction factor), and an axial stress balance. In addition, data obtained using the contour method have been included since it allows comparison of diffraction-based data to a technique that does not require a d0 value. In terms of residual stress, agreement between all d0 measurement techniques and the contour method was high, with the exception being those made using the Sin 2ψ technique. An offset of approximately 350 MPa was observed in these data, and a possible systematic error was ascribed to a unique diffraction characteristic of a γ/γ' nickel-base superalloy. A global d 0 value obtained using a stress balance or stress-free cube was found to be reliable throughout the sample bulk in cases where thermal processing was carried out at a slow rate, such as ageing. However, d0 differences equivalent to 400 me were observed between central and surface regions when a global d0 was applied to a water-quenched sample.

Original languageEnglish
Pages (from-to)219-228
Number of pages10
JournalJournal of Strain Analysis for Engineering Design
Volume48
Issue number4
DOIs
Publication statusPublished - 1 May 2013
Externally publishedYes

Keywords

  • Neutron diffraction
  • Nickel superalloy
  • Residual stress
  • Sinψ
  • X-ray diffraction

ASJC Scopus subject areas

  • Modelling and Simulation
  • Mechanics of Materials
  • Mechanical Engineering
  • Applied Mathematics

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