Crystallographic texture evolution in bulk deformation processing of FCC metals (original) (raw)
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International Journal of Mechanical Sciences, 1992
An approximate procedure for predicting the evolution of crystallographic texture during bulk deformation processing of fcc materials is proposed. The two steps in the proposed procedure are: (1) extract the history of the local deformation gradient in the neighborhood of a material point of interest with a finite element calculation using an isotropic plasticity model; (2) use this deformation gradient history in a separate Taylor-type polycrystai model calculation outside the finite element procedure, to predict the evolution of crystallographic texture at the material point of interest. Using this approximate but quicker procedure we have simulated two different plane-strain forgings of initially isotropic OFHC copper, and evaluated the accuracy of the procedure by comparing predictions for the overall load-displacement curves and texture evolution against corresponding experimental results. The two-step approximate procedure is shown to work well for the high-symmetry fcc copper formed in closed dies. NOTATION S R. KALID1ND! and L. ANAND
An Experimental and Analytical Study of the Evolution of Crystallographic Texturing in FCC Materials
Textures and Microstructures, 1991
A Taylor type polcrystalline model, together with a new fully implicit time integration scheme have been developed to simulate the evolution of crystallographic texture during the deformation of face centered cubic metals deforming by crystallographic slip. The constitutive equations include a new equation for the evolution of slip system deformation resistance which leads to realistic macroscopic strain hardening behavior. The good predictive capabilities of the constitutive equations and the time integration procedure are demonstrated by comparing numerical simulations against experimental texture measurements and stress-strain results in a series of homogeneous deformation experiments on OFHC copper.
Materialwissenschaft und Werkstofftechnik, 2005
In this paper, we report predicted results for texture evolution in FCC metals under uniaxial compression test. These results are computed using a newly developed nonlinear rigid viscoplastic crystal plasticity model based on an intermediate interaction law. This interaction law is formulated by the minimization of a normalized error function which combines the local fields' deviations, from the macroscopic ones, obtained by the classical upper bound (Taylor) and lower bound (Sachs) models. This interaction law leads to results lying between the upper and lower bound approaches by simply varying a scalar weight function f (0 < f < 1). A simple interaction law based on the linear mixture of the fields from the Taylor and Sachs models is also used. The results from these both the linear and nonlinear intermediate approaches are shown in terms of texture evolution under uniaxial compression. These results are discussed in comparison with the well known experimental textures in compressed FCC metals. Finally, we show that the linear intermediate approach yields fairly acceptable texture predictions under compression and that the fully non-linear approach predicts much better results.
Acta Materialia, 2012
We present crystal plasticity finite element simulations of the texture evolution in a-brass polycrystals under plane strain compression. The novelty is a non-crystallographic shear band mechanism [Anand L, Su C. J Mech Phys Solids 2005;53:1362] that is incorporated into the constitutive model in addition to dislocation and twinning. Non-crystallographic deformation associated with shear banding leads to weaker copper and S texture components and to a stronger brass texture compared to simulations enabling slip and twinning only. The lattice rotation rates are reduced when shear banding occurs. This effect leads to a weaker copper component. Also, the initiation of shear banding promotes brass-type components. In summary the occurrence of non-crystallographic deformation through shear bands shifts face-centered-cubic deformation textures from the copper type to the brass type.
Acta Materialia
"We present crystal plasticity finite element simulations of the texture evolution in a-brass polycrystals under plane strain compression. The novelty is a non-crystallographic shear band mechanism [Anand L, Su C. J Mech Phys Solids 2005;53:1362] that is incorporated into the constitutive model in addition to dislocation and twinning. Non-crystallographic deformation associated with shear banding leads to weaker copper and S texture components and to a stronger brass texture compared to simulations enabling slip and twinning only. The lattice rotation rates are reduced when shear banding occurs. This effect leads to a weaker copper component. Also, the initiation of shear banding promotes brass-type components. In summary the occurrence of non-crystallographic deformation through shear bands shifts face-centered-cubic deformation textures from the copper type to the brass type."
Acta Materialia, 2007
The ability of three different crystal plasticity finite element models to predict deformation textures in face-centered cubic metals observed in experiments is assessed. These methods are: (i) Taylor averaging, in which the interactions of the grains are considered in a homogenized manner; (ii) low-resolution simulation (LRS), in which grain interactions are considered explicitly albeit with low resolution; and (iii) direct numerical simulation (DNS), which provides high-resolution details of the deformation fields inside the grains and of the grain interactions. A quantitative comparison of the numerical results provided by these three methods against experimental plane-strain compression textures is performed via orientation distribution functions and fiber line analysis. It is found that some details of the texture which are inaccessible to either Taylor averaging and LRS approaches are captured by the DNS approach. This can be explained by the ability of the high-resolution DNS method to describe details of the grain interactions, including heterogeneous deformation under homogeneous macroscopic strain and smooth gradients of lattice rotations inside the grains which are missing in low-resolution models.
International Journal of Plasticity, 2001
The main issues and challenges involved in modeling anisotropic strain hardening and deformation textures in the low stacking fault energy (SFE) fcc metals (e.g. brass) are reviewed and summarized in this paper. The objective of these modeling eorts is to capture quantitatively the major dierences between the low SFE fcc metals and the medium (and high) SFE fcc metals (e.g. copper) in the stress±strain response and the deformation textures. While none of the existing models have demonstrated success in capturing the anisotropy in the stress±strain response of the low SFE fcc metals, their apparent success in predicting the right trend in the evolution of deformation texture is also questionable. There is ample experimental evidence indicating that the physical mechanism of the transition from the copper texture to the brass texture is represented wrongly in these models. These experimental observations demonstrate clearly the need for a new approach in modeling the deformation behavior of low SFE fcc metals. This paper reports new approaches for developing crystal plasticity models for the low SFE fcc metals that are consistent with the reported experimental observations in this class of metals. The successes and failures of these models in capturing both the anisotropic strain hardening and the deformation textures in brass are discussed in detail. #
A new intermediate model for polycrystalline viscoplastic deformation and texture evolution
Acta Materialia, 2008
In this paper, we propose a model for large viscoplastic deformation of polycrystalline materials called /-model. The proposed interaction law is based on a new non-linear intermediate approach. In this formulation, we propose to minimize an error function which combines the deviations of the local fields from the corresponding macroscopic ones. A scalar weight parameter was introduced to span the entire solution domain between the upper and lower bound approaches. We applied this approach to predict the stress-strain response and texture evolution in face-centered cubic metals under tension, compression and plane strain compression. We analyzed the effect of the weight parameter in terms of slip activity, stress-strain responses and texture transitions such as copper-type vs. brass-type textures. A comparison between the self-consistent model (VPSC code) and the /-model is also performed in this paper. Some possible links between the / parameter and microstructural features are also discussed.
Archives of Metallurgy and Materials, 2015
Microstructure and texture development in medium-to-high stacking fault energy face centred cubic metals were investigated in order to examine the role of lattice re-orientation on slip propagation across grain boundaries and to characterize the influence of micro- and macro-scale copper-type shear bands on textural changes at large deformations. Polycrystalline pure copper (fine - and coarse - grained) and fine-grained AA1050 alloy were deformed in plane strain compression at room temperature to form two sets of well-defined macroscopic shear bands. The deformation-induced sub-structures and local changes in crystallographic orientations were investigated mostly by scanning electron microscopy equipped with high resolution electron backscattered facility. In all the deformed grains within macro- shear bands a strong tendency to strain-induced re-orientation was observed. The flat, strongly deformed grains exhibited a deflection within narrow areas. The latter increased the layers’ ...