Cyclic stress relaxation of polycrystalline metals at elevated temperature

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Abstract

The influence of a relatively small, superimposed alternating strain on the relaxation behavior of structural metals is examined from the micro-mechanics standpoint, taking into account the nature of crystallographic slip in the grain and grain interactions. The initial mean strain is allowed to be sufficiently large to include both elastic and plastic components; it thus possibly causes an instant relaxation due to plastic deformation. To facilitate the evaluation of this instantly relaxed stress state Hill's self-consistent relation for an elastoplastic polycrystal is modified from its incremental to a total form for a monotonic straining process. The self-consistent relation previously derived for static relaxation of an elastic-creep medium is also extended to the dynamic condition, and for an elastic-plastic-creep medium. Together with a set of unified constitutive equations of slip systems, these self-consistent relations are used to determine the cyclic relaxation behavior of a 0.16% carbon steel at various strain amplitudes. The results are seen to be in close agreement with the experimental data, both showing that the relaxation of mean stress could be greatly facilitated by the presence of a small strain amplitude. This accelerated process is attributed to the two factors: the additional plastic flow caused by the alternating strain and the nonlinear stress-dependency of the creep rate.

Original languageEnglish (US)
Pages (from-to)541-550
Number of pages10
JournalInternational Journal of Solids and Structures
Volume19
Issue number6
DOIs
Publication statusPublished - 1983

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All Science Journal Classification (ASJC) codes

  • Modeling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Applied Mathematics

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