Determination and interpretation of texture evolution during deformation of a zirconium alloy

V. M. Allen, J. Quinta Da Fonseca, M. Preuss, J. D. Robson, M. Daymond, R. J. Comstock

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther

3 Citations (Scopus)

Abstract

Worldwide, crystal plasticity models are currently developed to predict texture development during processing of material. Such models require a precise knowledge of the active deformation mechanisms. The activation energy for certain deformation modes will change with temperature and also depend on the chemistry of the alloy as well as the microstructure. Deformation mechanisms were studied in ZIRLO™ during room and high-temperature uniaxial compression testing. Materials with a strong crystallography basal texture and a more random texture due to β-quenching were investigated with the aim of establishing the effect of temperature, microstructure, and texture on the active deformation modes during the initial stages of deformation. First, specimens were strained at room temperature, 180°C and 300°C to 2 % and 5 % or 10 % total strain and subsequently analyzed by Electron Back Scatter Diffraction (EBSD) to determine the texture evolution. It was found that a dramatic texture change was observed for all testing temperatures in the strongly textured specimen after only 5 % total strain, which can only be understood in terms of tensile twinning of {101̄2} 〈1011〉 being active mainly at room temperature and compressive twinning of {112̄2} (1̄1̄23) being operational at room and elevated temperature. The β-quenched specimens did not show any evidence of texture change when strained to 10 %. In-situ intergranular strains were measured by time-of-flight neutron diffraction during continuous compressive loading. This information enabled the development of a crystal plasticity finite element model (CPFEM), which was subsequently used to predict the stress state in individual grains. It was found that in the strongly textured material the spread of intergranular strain in the {0002} grain family (normal pointing towards the ND direction) results in some grains being in compression even though the mean stresses are tensile, which could explain the activation of the observed compressive twinning. The crystal plasticity model also demonstrated that the observed texture changes in the strongly textured material, including those at high temperature, cannot be explained by slip alone even when 〈c+a〉 slip is considered. In addition, the model showed that the dramatic difference in yield strength of the two conditions studied here cannot be solely attributed to the difference in texture but that grain size plays an important role.

Original languageEnglish
Title of host publicationZirconium in the Nuclear Industry
Subtitle of host publication15th International Symposium
PublisherAmerican Society for Testing and Materials (ASTM)
Pages550-563
Number of pages14
ISBN (Print)9780803145146
DOIs
Publication statusPublished - 2009
Externally publishedYes
EventInternational Symposium on Zirconium in the Nuclear Industry 2007 - Sunriver, United States of America
Duration: 24 Jun 200728 Jun 2007
Conference number: 15th

Publication series

NameASTM Special Technical Publication
Volume1505 STP
ISSN (Print)0066-0558

Conference

ConferenceInternational Symposium on Zirconium in the Nuclear Industry 2007
Country/TerritoryUnited States of America
CitySunriver
Period24/06/0728/06/07

Keywords

  • Intergranular strain
  • Microstructure
  • Plasticity modelling
  • Texture
  • ZIRLO™

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