Real hydrostatic pressure in high-pressure torsion measured by bismuth phase transformations and FEM simulations

Kaveh Edalati, Dong Jun Lee, Takashi Nagaoka, Makoto Arita, Hyoung Seop Kim, Zenji Horita, Reinhard Pippan

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    Hydrostatic pressure is a significant parameter influencing the evolution of microstructure and phase transformations in the high-pressure torsion (HPT) process. Currently, there are significant arguments relating to the magnitude of the real hydrostatic pressure during the process. In this study, phase transformations in bismuth, copper and titanium combined with the finite element method (FEM) were employed to determine the real pressure in processing disc samples by HPT. Any break in the variation of steady-state hardness (monitored experimentally by in-situ torque and temperature rise measurements) versus pressure was considered as a phase transition. FEM simulations show that the hydrostatic pressure is reasonably isotropic but decreases with increasing distance from the disc center and remains unchanged across the disc thickness. Both experiments and simulations indicate that the mean hydrostatic pressure during HPT processing closely corresponds to the compressive load over the disc area plus the contact area between the anvils.

    Original languageEnglish
    Pages (from-to)533-538
    Number of pages6
    JournalMaterials Transactions
    Volume57
    Issue number4
    DOIs
    Publication statusPublished - 2016

    All Science Journal Classification (ASJC) codes

    • Materials Science(all)
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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