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Title: Stress and strain relaxation in magnesium AZ31 rolled plate: In-situ neutron measurement and elastic viscoplastic polycrystal modeling

Continuous mechanical tests with strain holds (stress relaxation) and with stress holds (strain relaxation) are performed simultaneously with in-situ neutron measurements to analyze the mechanisms of stress and strain relaxation in Mg AZ31 rolled plate. A dislocation activity based constitutive model, accounting for internal stress statistical distributions, is proposed and implemented into an elastic viscoplastic self-consistent (EVPSC) framework to simultaneously describe both stress and strain relaxation. The model captures the experimental data in terms of macroscopic stress strain curves, evolution of stress and strain during holding, as well as evolution of the internal elastic strains. Model results indicate that the magnitude of the stress relaxed during strain holding is dependent on both, the magnitude of the flow stress and the spread of the resolved shear stress distribution. The magnitude of strain accumulated during stress holding is, on the other hand, dependent on the magnitude of the hardening rate and on the spread of the resolved shear stress distribution. Furthermore, the internal elastic strains are directly correlated with the stress state, and hence the stress relaxation during strain holds has a greater influence on the lattice strains than strain relaxation during stress holds.
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Georgia Inst. of Technology, Atlanta, GA (United States); Georgia Tech-CNRS, Metz (France)
Publication Date:
Report Number(s):
Journal ID: ISSN 0749-6419
Grant/Contract Number:
AC52-06NA25396; FWP 06SCPE401
Accepted Manuscript
Journal Name:
International Journal of Plasticity
Additional Journal Information:
Journal Volume: 79; Journal Issue: C; Journal ID: ISSN 0749-6419
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; strain relaxation; A. stress relaxation; magnesium alloy; neutron diffraction; stress distribution
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1252024