The effect of precipitate-induced backstresses on plastic anisotropy: Demonstrated by modeling the behavior of aluminum alloy, 7085. (June 2019)

• Record Type: Journal Article
• Authors: Bhattacharyya, J.J.; Bittmann, B.; Agnew, S.R.
• Is Part Of: International journal of plasticity. Volume 117(2019:Jun.)
• Page Start: 3
• Page End: 20
• Publication Date: 2019-06
• Subjects: Anisotropy -- Backstress -- Precipitation hardening -- Self-consistent modeling -- Strain incompatibility -- Kolsky bar; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2018.04.011
• Languages: English
• ISSNs: 0749-6419

Abstract

Abstract: The constitutive response of commercial aluminum alloy 7085, is characterized under quasistatic (0.001 s −1 ) and high strain rate (1250 s −1 ) uniaxial compression loading along the rolling, transverse, and normal directions (RD, TD and ND, respectively) and at 45° to RD within the plane of the plate (henceforth denoted as 45) at different aging conditions, in order to see the effect of aging on the flow stress and plastic strain anisotropy. It is shown that with aging, the material tends towards isotropy, i.e., the in-plane plastic anisotropy is reduced. These results verify the previously hypothesized connection between precipitate induced-backstress and anisotropy. A model taking into account the kinematic hardening effect of an elastic inclusion within an elastoplastic single crystal has been incorporated into the elastoplastic self-consistent (EPSC) polycrystal modeling framework to quantitatively describe this effect of precipitates on plastic anisotropy. Finally, the plastic anisotropy, during compressive straining parallel to the normal direction, is shown to be remarkably sensitive to the initial texture. Highlights: Evolution of strength and plastic strain anisotropy with aging is measured for AA7085. With aging, the in-plane r-values tend toward 1; the material becomes more isotropic. A model accounting for kinematic hardening due to particles is employed. The original formulation is modified to eliminate the inversion of the ill-conditioned grain elastoplastic stiffness. Accounting for backstress with plastic relaxation enables the predictions to agree with observations.