Single crystal shear (original) (raw)
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Single crystal deformation of Aluminium
polymer substrates. The type of conductive filler considerably determines the characteristics of nucleation, growth and the electroforming of the product microstructures.
1999
To bridge length scales in plastic flow of polycrystalline fcc metals, the salient features of 3D polycrystalline elastoviscoplasticity at the crystal level (mesoscale) were studied to determine the relative influences on macroscale behaviour. This 3D study builds upon the 2D planar doubleslip analysis performed by Horstemeyer and McDowell in which the relative influence of the constitutive-law features on macroscale properties in polycrystal plasticity were quantified for oxygen-free, high-conductivity copper. The mesoscale constitutive-law features considered include single-crystal elastic properties, slip-system-level hardening law, latent hardening, slip-systemlevel kinematic hardening, and intergranular constraint relation. Volume-averaged macroscale responses included the effective flow stress, plastic spin, elastic moduli, hardening behaviour, and axial extension (for the free-end torsion case). Each response was evaluated at 10% and 50% effective strain levels under rectilinear shear straining. In the existing literature, only one type of behaviour (e.g. texture or stress-strain response) is typically considered when assessing these various elements of the constitutive framework. In this paper, we develop a more comprehensive understanding of the relative importance of constitutive-law features as deformation proceeds. This study suggests that the design of experiments methodology is a valuable tool to assist in selecting relevant features for polycrystalline simulations and for development of macroscale unified-creepplasticity models. In general, the results indicated that the intergranular constraint and kinematic hardening were more influential overall than the type of constitutive model used, whether isotropic or anisotropic elasticity was used, and whether or not latent hardening was used. Finally, 3D results were similar to the previous 2D planar double-slip study of Horstemeyer and McDowell, except that latent hardening had a stronger influence on the 3D macroscale responses than the 2D macroscale responses.
Texture and largestrain deformation microstructure
… of the Royal …, 1999
Large-strain plastic deformation at low homologous temperature implies, among other things, severe work hardening, strong crystallographic texturing, microstructural refining, and some degree of macroscopic redundant strain. In most cases, the development of texture does not seem to particularly increase grain interactions above their initial level, which is at the origin of the Hall-Petch effect. Continued strain then leads asymptotically towards an absolute maximum of the tensile flow stress below G/50, where G represents the elastic shear modulus. However, it is well known that some simple deformation textures promote an extraordinary enhancement of the plastic grain interactions that need to be accommodated by monotonically increasing mesoscopic (grain-size range) strain gradients. Such behaviour is accompanied by a concomitant high work-hardening rate and by a remarkable extension of the strengthening limit. The [110] body-centred-cubic or [0001] hexagonal close-packed wire drawing textures constitute the paradigmatic case, for which the flow stress limit reaches up to G/20. A quantitative explanation of the phenomenon is given here with the help of a geometrical model of microstructural development.
Advanced Engineering …, 2001
This article reviews continuum-based variational formulations for describing the elastic-plastic deformation of anisotropic heterogeneous crystalline matter. These approaches, commonly referred to as crystal plasticity finite-element models, are important both for basic microstructure-based mechanical predictions as well as for engineering design and performance simulations involving anisotropic media. Besides the discussion of the constitutive laws, kinematics, homogenization schemes and multiscale approaches behind these methods, we also present some examples, including, in particular, comparisons of the predictions with experiments. The applications stem from such diverse fields as orientation stability, microbeam bending, single-crystal and bicrystal deformation, nanoindentation, recrystallization, multiphase steel (TRIP) deformation, and damage prediction for the microscopic and mesoscopic scales and multiscale predictions of rolling textures, cup drawing, Lankfort (r) values and stamping simulations for the macroscopic scale.
Materials Processing and Texture, 2008
Four crystal plasticity codes, the viscoplastic Material Point Simulator (MPS) developed at Cornell and the ViscoPlastic Self-Consistent code (VPSC7b) developed at LANL, and two elastic-viscoplastic codes developed at Drexel University, were employed to calculate deformation textures and mechanical properties of model polycrystalline specimens by simulating isochoric, free upsetting. Uniaxial compression of a model sample with a starting random texture of 5000 grains was carried out at a constant true strain rate of 0.001/s to a true strain of 1.0 with 0.02 strain increments. Material properties simulated a face-centered cubic (FCC) alloy, Type 304 Stainless Steel, and a hexagonal close-packed (HCP) material, unalloyed Ti. Both non-hardening and linear hardening conditions were investigated. Different strain-rate sensitivities simulated deformation conditions appropriate to ambient and elevated temperature conditions. All codes permitted use of the Taylor homogenization hypothesis, resulting in an upper bound for the mechanical properties. All codes produce essentially identical results for the same input material, homogenization hypothesis and deformation conditions. For comparison, one alternative homogenization hypothesis to model grain interactions was examined for each of the MPS and VPSC7b codes.
Modeling of Severe Plastic Deformation: Evolution of Microstructure, Texture, and Strength
Integral Materials Modeling, 2007
Severe plastic deformation processes involve large grain rotations due to the action of different modes of plastic deformation and other microstructural changes which lead to characteristic texture formation. The present review deals with the evolution of texture during the most important severe plastic deformation processes, namely Equal Channel Angular Pressing (ECAP), High Pressure Torsion (HPT), Friction Stir Processing (FSP), Accumulative Roll Bonding (ARB) and Multi-Axial Forging (MAF). First three of the processes are shear based, while the latter two are plane-strain based. The textures formed during ECAP are visually different from simple shear textures due to (i) the inclination of the shear plane, (ii) additional contribution of non-shear based deformation. The relative intensities of texture components are function of deformation micro-mechanisms, amount of straining and configuration of the strain path. The texture evolved during HPT is very similar to simple shear texture, with additional consequences of microstructural changes that occur due to very large deformations. The textures formed in FSP process also resemble shear textures. On the other hand, texture evolution during ARB and MAF can be described using plane strain deformation. The present review deals with texture evolution during severe plastic deformation as a function of nature of processes and type of materials.
Metals, 2018
In this study, for the first time, the effect of large non-monotonic simple shear strains on the uniformity of the tensile properties of pure Cu specimens was studied and justified by means of microstructural and textural investigations. A process called simple shear extrusion, which consists of two forward and two reversed simple shear straining stages on two different slip planes, was designed in order to impose non-monotonic simple shear strains. Although the mechanism of grain refinement is continuous dynamic recrystallization, an exceptional microstructural behavior and texture were observed due to the complicated straining path results from two different slip planes and two pairs of shear directions on two different axes in a cycle of the process. The geometry of the process imposes a distribution of strain results in the inhomogeneous microstructure and texture throughout the plane perpendicular to the slip plane. Although it is expected that the yield strength in the periphe...