Effects of the isotropic and anisotropic hardening within each grain on the evolution of the flow stress, the r-value and the deformation texture of tensile tests for AA6016 sheets

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:721

Article

Xie, Q.^1,6  Van Bael, A.²  An, Y. G.³  Lian, J.⁴  Sidor, J. J.⁵ 

[1] Univ Sci & Technol Beijing, SKLAMM, Beijing 100083, Peoples R China

[2] Katholieke Univ Leuven, Dept Met & Mat Engn, B-3001 Heverlee, Belgium

[3] Tata Steel, Applicat & Engn Res & Dev, NL-1970 CA Ijmuiden, Netherlands

[4] Rhein Westfal TH Aachen, Steel Inst, Intzestr 1, D-52072 Aachen, Germany

[5] Eotvos Lorand Univ, Savaria Inst Technol, Fac Informat, Karolyi Gaspar Ter 4, H-9700 Szombathely, Hungary

[6] Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA

关键词: AA6016;    Anisotropic hardening;    R-value;    Flow stress anisotropy;    Dislocation interactions;   

DOI  :  10.1016/j.msea.2018.02.053

来源: Elsevier

【 摘 要 】

Both the isotropic and anisotropic hardening laws implemented in a crystal elastic visco-plastic finite element model (CEPFEM) were tested for the prediction of the flow stress, the r-value and the deformation texture for tensile tests of the AA6016 sheet. The isotropic hardening law provides good predictions of the flow stress anisotropy. The dislocation hardening was found to be dominant in the hardening behavior. By accounting for the strength variety of different dislocation junctions, predictions of the anisotropic hardening law are sensitive to the activity/strength of different dislocation junctions. Both the plastic shear of slip systems and the dominant dislocation junctions are grain orientation dependent. The flow stress level correlates with the strength of particular dislocation junctions. Both hardening models give similar predictions of the r-value and the deformation texture. Although the physics of crystal plasticity is implemented by including the strength difference of different dislocation junctions, the predictions have not significantly improved. This demonstrates that the strength of dislocation junctions is not responsible for explaining the limitation of the isotropic hardening model. Since the latter does not suffer from neglecting the strength variety of different dislocation junctions, the less complicated isotropic hardening model may still be used as such.

【 授权许可】

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