Evaluation of self-consistent polycrystal plasticity models for magnesium alloy AZ31B sheet

Abstract

a b s t r a c tVarious self-consistent polycrystal plasticity models for hexagonal close packed (HCP) polycrystals are evaluated by studying the deformation behavior of magnesium alloy AZ31B sheet under different uniaxial strain paths. In all employed polycrystal plasticity models both slip and twinning contribute to plastic deformation. The material parameters for the various models are fitted to experimental uniaxial tension and compression along the rolling direction (RD) and then used to predict uniaxial tension and compression along the traverse direction (TD) and uniaxial compression in the normal direction (ND). An assessment of the predictive capability of the polycrystal plasticity models is made based on comparisons of the predicted and experimental stress responses and R values. It is found that, among the models examined, the self-consistent models with grain interaction stiffness halfway between those of the limiting Secant (stiff) and Tangent (compliant) approximations give the best results. Among the available options, the Affine self-consistent scheme results in the best overall performance. Furthermore, it is demonstrated that the R values under uniaxial tension and compression within the sheet plane show a strong dependence on imposed strain. This suggests that developing anisotropic yield functions using measured R values must account for the strain dependence.

Influence of texture on the recrystallization mechanisms in an AZ31 Mg sheet alloy at dynamic rates

“…A deformation texture, in which basal planes are parallel to the rolling plane and (10-10) directions are parallel to the loading axis (RD), becomes progressively better defined with increasing deformation. This reveals that the main deformation mechanism is prismatic slip, together with basal slip [4,5,40,41]. At the largest strain level investigated (0.20, Fig.…”

“…Accordingly, the grain size increases to 12|jim, as twin propagation has now basically encompassed the entire grains and very few twin boundaries remain. It is well known that the twinned regions, in which the compression axis is parallel to the c-axes, pyramidal (c + a) and basal slip are the predominant deformation mechanisms [39,40]. As shown in Figs.…”

“…A summary of the CRSS obtained from single crystal experiments can be found in [7]. These values are of the order of 5 MPa for basal slip, lOMPa for extension twinning, 20 MPa for prismatic slip, 40 MPa for pyramidal slip and 70-80 MPa for contraction twinning. Thus, in the highly textured alloys resulting from conventional rolling or extrusion processes the predominant mechanisms will depend strongly on the loading mode (tension or compression) as well as on the loading direction with respect to the c-axes of the polycrystalline aggregate [4][5][6]8].…”

The Influence of Strain Path on Rare Earth Recrystallization Textures in a Magnesium-Zinc-Rare Earth Alloy

“…The code used in the present work is that developed at Los Alamos by Lebensohn and Tome´[ 17,18] and has been proven for the simulation of magnesium deformation including slip and twinning. [19,20] Note that the VPSC model considers only homogeneous deformation, and does not account for strain localization effects (e.g., shear banding).…”

On twinning and anisotropy in rolled Mg alloy AZ31 under uniaxial tension

“…[26] have demonstrated that the predicted response of a polycrystal is very sensitive to the self-consistent scheme employed. Wang et al [30] have evaluated various self-consistent schemes used in selfconsistent modeling by applying them to the large strain behavior of magnesium alloy AZ31B plate under different deformation processes. It was found that the Affine self-consistent scheme gave the best overall performance among the self-consistent approaches examined.…”