Influence of strain rate on mechanical properties and deformation texture of hot-pressed and rolled beryllium

Plastic deformation of hexagonal metals such as beryllium occurs by a mix of dislocation slip and deformation twinning mechanisms. Slip and twinning are controlled by different mechanisms at the atomic scale, and thus respond differently to variations in strain rate. In general, deformation twinning...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2010-07, Vol.527 (20), p.5181-5188
Main Authors: Sisneros, T.A., Brown, D.W., Clausen, B., Donati, D.C., Kabra, S., Blumenthal, W.R., Vogel, S.C.
Format: Article
Language:English
Subjects:
Beryllium
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Deformation
Deformation and plasticity (including yield, ductility, and superplasticity)
Deformation mechanisms
Deformation twinning
Exact sciences and technology
Materials science
Mechanical and acoustical properties of condensed matter
Mechanical properties of solids
Microstructure
Neutron diffraction
Other heat and thermomechanical treatments
Physics
Slip
Strain rate
Surface layer
Texture
Treatment of materials and its effects on microstructure and properties
Twinning
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Summary:Plastic deformation of hexagonal metals such as beryllium occurs by a mix of dislocation slip and deformation twinning mechanisms. Slip and twinning are controlled by different mechanisms at the atomic scale, and thus respond differently to variations in strain rate. In general, deformation twinning is expected to be favored by high strain rate conditions. Both textured and randomly textured polycrystalline beryllium samples were deformed at strain rates from 0.0001/s to 5000/s. The yield point was found to be strain rate insensitive over the 7+ orders of magnitude of strain rate. The hardening, however, is strongly rate dependent for some of the initial textures, depending on loading direction relative to the basal poles. Optical microscopy and neutron diffraction measurements of the crystallographic texture were carried out to monitor the evolution of the microstructure and, specifically, the activity of deformation twinning as a function of strain rate. The relative roles of the active slip and twin deformation mechanisms are linked to the observed rate dependence of the flow stress.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2010.04.035