In situ measurement of elastic and total strains during ambient and high temperature deformation of a polygranular graphite

Research output: Contribution to journalArticle (Academic Journal)

Abstract

In situ neutron diffraction and synchrotron X-ray diffraction, combined with image correlation analysis of 2D optical and 3D X-ray tomography datasets, have been used to investigate the relationship between elastic lattice strain and total strain during deformation of Gilsocarbon (IM1-24) polygranular nuclear grade graphite. The specimens were flat-end Brazilian discs under diametral loading, such that a compressive-tensile biaxial stress state was developed in the central region. The X-ray study was at ambient temperature, and the neutron diffraction was conducted at temperatures from ambient to 850 °C. When under compression, there is a temperature-insensitive linear relationship between the total strain and the lattice strain that is measured perpendicular to the graphite basal planes. However, when under tensile stress, the total strain and elastic strain relationship is temperature sensitive: below 600 °C, the lattice tensile strain saturates with increasing total tensile strain; above 600 °C, significantly higher tensile lattice strains are sustained. The saturation in tensile lattice strain is attributed to microcracking in the graphite microstructure. Improved resistance to microcracking and damage tolerance at elevated temperature explains the increase in tensile strength of polygranular graphite.
Original languageEnglish
Pages (from-to)308-323
JournalCarbon
Volume163
Early online date11 Mar 2020
DOIs
Publication statusPublished - 2020

Keywords

  • Gilsocarbon graphite
  • Neutron diffraction
  • X-ray diffraction
  • X-ray computed tomography
  • Digital volume correlation

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