Samples of AA 6022 were deformed at different temperatures, strain and strain rates through channel die compression. Deformed samples, though quenched immediately after deformation, had both deformed grains/bands and recrystallized grains. Using a simple criterion of grain size and in-grain misorientation developments, respective deformed and recrystallized regions could be distinguished. Deformation temperature/strain rate, or the so-called Zener-Holloman (Z) parameter, had clear effects on the deformed microstructure in terms of orientation stability or textural changes and in terms of in-grain misorientation developments. These, in turn, strongly affected the associated recrystallization behavior including relative contributions from particle stimulated nucleation and contributions from deformed grains/bands of different ideal orientations.

The von Neumann-Mullins relation has been extended to higher dimensions by MacPherson and Srolovitz. Their exact solution relates the rate of volume change of ail individual grain in a 3-dimensional isotropic polycrystal to its mean width and total length of triple lines (assuming isotropic boundaries). The objective of this study is to verify that grains in a moving finite element grain growth model obey this law. Algorithms have been developed in order to calculate mean width of individual grains ill digital microstructures for which the grain structure is discretized with both volumetric and surface meshes. Theoretical rate predictions were obtained from the measured mean widths and triple line lengths. Good agreement was found between growth rates measured in the simulations and the predictions of MacPherson-Srolovitz theory for the cases of an isolated shrinking sphere, individual grains in a digitally generated coarse polycrystal, and individual grains in a microstructure reconstructed from serial sectioning of stabilized cubic zirconia. Departures front this relationship appeared to be related to the grain shape.

Three-dimensional finite element analysis of a bicrystal using a crystal plasticity constitutive theory was performed to compute the maximum plastic shear strain range Delta gamma(p)(max) in the matrix, at the particle/matrix interface, and at the bicrystal boundary. Using the finite element analysis results, a design of experiments (DOE) technique was employed to understand and quantify the effects of seven parameters on fatigue crack incubation: applied displacement, load ratio, particle modulus, the number of initially active slip systems, the relative crystallographic misorientation at the grain boundary, the particle aspect ratio, and the normalized particle size. The simulations clearly showed that the applied displacement is the most influential parameter. In most cases, particles were found to be more significant than bicrystal boundaries for incubation. The number of initially active slip systems, the particle aspect ratio, and the normalized particle size showed some influences on fatigue incubation. The particle modulus was the least influential parameter.

Three-dimensional finite element analysis using a crystal plasticity constitutive theory was performed to understand and quantify various parametric effects on microstructurally small fatigue crack growth in a AA7075 aluminum alloy. Plasticity-induced crack opening stresses (S-o/S-max) were computed, and from these results the crack propagation life N was obtained. A design of experiments (DOE) technique was used to study the influences of seven parameters (maximum load, load ratio, particle modulus, the number of initially active slip systems, misorientation angle, particle aspect ratio, and the normalized particle size) on fatigue crack growth. The simulations clearly showed that the load ratio is the most influential parameter on crack growth. The next most influential parameters are maximum load and the number of initially active slip systems. The particle modulus, misorientation angle, particle aspect ratio, and the normalized particle size showed less influence on crack growth. Another important discovery in this study revealed that the particles were more important than the grain boundaries for inducing resistance for microstructurally small fatigue crack growth.

Three-dimensional finite element analysis of a bicrystal using a crystal plasticity constitutive theory was performed to compute the maximum plastic shear strain range Delta gamma(p)(max) in the matrix, at the particle/matrix interface, and at the bicrystal boundary. Using the finite element analysis results, a design of experiments (DOE) technique was employed to understand and quantify the effects of seven parameters on fatigue crack incubation: applied displacement, load ratio, particle modulus, the number of initially active slip systems, the relative crystallographic misorientation at the grain boundary, the particle aspect ratio, and the normalized particle size. The simulations clearly showed that the applied displacement is the most influential parameter. In most cases, particles were found to be more significant than bicrystal boundaries for incubation. The number of initially active slip systems, the particle aspect ratio, and the normalized particle size showed some influences on fatigue incubation. The particle modulus was the least influential parameter.

The main aim of this work was to develop a model with predictive capability for microstructural evolution during recrystallization and to identify factors that exert the greatest effect on the development of texture. To achieve this aim, geometric and crystallographic observations from two orthogonal sections through a polycrystal were used as input to the computer simulations, to create a statistically representative three-dimensional model. Assignment of orientations to the grains was performed so as to optimize agreement between the orientation and misorientation distributions of assigned and observed orientations. The microstructures thus created were allowed to evolve using a Monte Carlo simulation. As a demonstration of the model the effects of anisotropy, both in energy and in mobility, stored energy and oriented nucleation (ON) on overall texture development were studied. The results were analyzed with reference to the various established competing theories of ON and oriented growth. The results suggested that all of ON, mobility anisotropy, stored energy and energy anisotropy (listed in order of their relative importance) influence texture development. It was also determined that comparison of simulated and measured textures throughout the recrystallization process is a more severe test of a model than the typical comparison of textures only at the end of the process.

This paper is based on the comparison of the cold-rolling and subsequent annealing behavior of two hcp metals (cp-Ti and Zr702). A special attention is paid to the consequences of deformation twinning on texture and microstructure evolutions. The Ti sheet develops an important amount of twins in the first stages of deformation, whereas the Zr702 sheet deforms by slip only. Twinning is a very efficient grain fragmentation mechanism. It generates specific texture components at medium strains which smear out after 80\% thickness reduction. Recrystallization mechanisms and kinetics are sensitive to the deformation substructure types and therefore to the occurrence of twinning. However the texture evolves quite few during recrystallization after 80\% cold-rolling in both materials. Twinning orientation relationships are promoted in the misorientation distributions of the deformed microstructures but also slightly show up in the grain boundary populations of recrystallized materials.

An efficient full-field formulation based on Fast Fourier Transforms (FFT) for the prediction of the viscoplastic deformation of polycrystals is applied to the study of the subgrain texture and microstructure evolution in polycrystalline copper deformed under tension. Direct input from Orientation Imaging Microscopy (OIM) images is used in the construction of the initial unit cell. Average orientations and misorientations predicted after 11\% tensile strain are directly compared with OIM measurements, showing good agreement. The differences between misorientations of surface grains compared with bulk grains are estimated, and the orientation dependence of intragranular misorientations is studied. Measurements and simulations agree in that grains with initial orientation near <110> tend to develop higher misorientations. This behavior can be explained in terms of attraction towards the two stable orientations and grain interaction. Only models that account explicitly for interaction between individual grains, like the FFT-based formulation, are able to capture these effects

Microstructure sensitive design was used in this study to design a textured soft magnet material to meet a range of magnetic properties. The evolution of microstructure and magnetic properties during mechanical processing was simulated and presented in a spectral representation for microstructure (texture hull) and magnetic property (property hull). The set of properties for a single path (or multiple processing paths) is represented in the property hull with a direct link to the range of desired microstructures. A methodology is proposed to achieve microstructures satisfying the requirement of multiple properties.