ISSN: 1546-962X
Published Online: 24 August 2007
Page Count: 13

Strain Hardening During Mechanical Twinning and Dislocation Channeling in Irradiated 316 Stainless Steels
Byun, T. S.
Oak Ridge National Laboratory, Oak Ridge

Hashimoto, N.
Oak Ridge National Laboratory, Oak Ridge

(Received 19 June 2006; accepted 27 July 2007)

Abstract

Localized deformation mechanisms and strain-hardening behaviors in irradiated 316 and 316LN stainless steels were investigated, and a theoretical model was proposed to explain the linear strain-hardening behavior during the localized deformation. After low temperature irradiation to significant doses, the deformation microstructure changed from dislocation tangles to channels or mechanical twins. It was also observed that irradiation hardening straightened gliding dislocations and increased the tendency for forming pileups. Regardless of these microstructural changes, the strain-hardening behavior was relatively insensitive to the irradiation. This dose-independent strain-hardening rate resulted in dose independence of the true stress parameters, such as the plastic instability stress and true fracture stress. In the proposed model, the long-range back stress was formulated as a function of the number of pileup dislocations per slip band and the number of slip bands in a grain. The calculation results confirmed the experimental observation that strain-hardening rate was insensitive to the change in deformation mechanism because the long-range back stress hardening became as high as the hardening by tangled dislocations.

Keywords:
radiation effect, strain-hardening behavior, strain localization, dislocation channels, mechanical twins, long-range back stress, pileup dislocations

Paper ID: JAI100680
DOI: 10.1520/JAI100680
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