• Zezhou Li
  • Bingfeng Wang
  • Shiteng Zhao
  • Ruslan Z. Valiev
  • Kenneth S. Vecchio
  • Marc A. Meyers

Dynamic deformation and shear localization of ultrafine-grained (∼120 nm) pure titanium are examined. The strain hardening can be considered as having two regimes: below and above a strain ∼0.04; at this point there is a drastic decrease in the slope. The strain-rate sensitivity of ultrafine-grained titanium is found to be approximately the same as its coarse grained counterpart. Based on experimentally determined parameters, the Zerilli-Armstrong equation is modified to describe the mechanical response of the ultrafine-grained titanium over the strain rate range 10−5 to 103 s−1. Adiabatic shear banding is examined in a forced shear configuration where large strain is imposed in a narrow region. The microstructure inside the adiabatic shear band consists of a mixture of elongated grains and equiaxed nanograins (∼40 nm) that are significantly smaller than the initial grains (∼120 nm). The formation of equiaxed nanograins is modeled through a mechanism of rotational dynamic recrystallization. This further reduction in grain size from the one generated by ECAP is interpreted in terms of the Zener-Hollomon parameter for quasistatic and dynamic deformation. The adiabatic shear band eventually fractures by a combination of brittle and ductile failure.

Original languageEnglish
Pages (from-to)210-218
Number of pages9
JournalActa Materialia
Volume125
DOIs
StatePublished - 15 Feb 2017
Externally publishedYes

    Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

    Research areas

  • Adiabatic shear band formation and failure mechanism, Constitutive response, Ultrafine-grained titanium

ID: 35163780