Textures of Materials - ICOTOM 14

Paper Title Page

Authors: Chris H.J. Davies, Sang Bong Yi, Jan Bohlen, Karl Ulrich Kainer, Heinz Günter Brokmeier
Abstract: The crystallographic response to deformation – texture evolution, internal elastic strain, and twin evolution – was measured for three load/orientation variants for AZ31 magnesium alloy extrudate tested in-situ in a synchrotron beamline. Specimens were loaded in tension parallel to the extrudate transverse direction, in compression along the same axis, and in compression parallel to the extrudate normal direction. The crystallographic responses are correlated with the mechanical behaviour of the extrudate.
Authors: Laurent Delannay, M. Béringhier, Yvan Chastel, Roland E. Logé
Abstract: This paper presents a means of reducing the computational cost of finite element (FE) simulations coupled to polycrystal plasticity theory. One typically assumes that a polycrystal with a large number of grains underlies every integration point of the FE mesh. Instead, it is suggested here using reduced samplings of grains which differ from one integration point to another. On average, every set of 5 to 25 finite elements contains a variety of lattice orientations that is representative of the macroscopic texture. The model is applied to deep-drawing of a cylindrical cup made of steel. In a first set of simulations, grains are assigned orientations representative of a cold rolling texture and the “earing” profile is compared to experiment. In a second set of simulations, lattice orientations are random and an isotropic deep-drawing result is expected. It is demonstrated that using a minimum of 20 grains per integration point allows properly predicting the final shape of the cup and the texture development.
Authors: K. Linga Murty, R. Kishore, J. Yan, Ron O. Scattergood, A.W. Helsel
Abstract: Effect of annealing temperature is investigated on texture and creep anisotropy in a thinwalled tubing of titanium alloy. Creep anisotropy is studied under equibiaxial loading using internally pressurized tubing superimposed with axial load while monitoring in-situ the time variations of both hoop and axial strains. Relatively weak hoop direction in the cold-worked material became stronger following complete recrystallization. The analyses of the data reveal that the anisotropy parameter, P which is the contractile strain ratio for testing along hoop direction increases from around 0.6 for the cold-worked material to around 1.5 following complete recrystallization. Results indicate that planar isotropy should occur following annealing at around 800K. Work on the effects of annealing on the textures and deformation microstructures is in progress. We summarize here results from some of our earlier work on a different lot of Ti3Al2.5V tubing in the recrystallized states where the ODFs were used in conjunction with crystal slip models to predict creep anisotropy.
Authors: Qiu Lin Wu, Wei Fang, Xiao Jun Hu, Zuming Fu, Limin Li
Abstract: For multi crystal materials, particularly multi-crystal metallic materials, it is unavoidable to make its crystal orientation change during the process. For instance, improving the property of soft magnetic materials should rely on the Cubic texture {100} <001>, but the property of the deep-draw sheet materials is closely related to its texture. Besides the material's composition, the crystal and the microstructure, the texture also takes a very important role in the properties of the materials [1, 2]. The positive pole figure analytic method is comparatively simple and intuitional. This is unquestionable in the texture analysis of cold-rolled samples, as in drawing sheet materials. It shows that the material orientation of isotropy or multiple weak textured materials is coexistent. The ODF analysis can be a good method for resolving this. In the study, the serial ODF analysis is used to analyze the property of nickel based alloys of drawing sheet materials considering different deformation amount, annealing temperature and annealing time in layers. In practice, it can be applied to production techniques.
Authors: L. Neumann, R. Kopp, H. Aretz, Mischa Crumbach, Matthias Goerdeler, Günter Gottstein
Authors: Dierk Raabe, A. Al-Sawalmih, P. Romano, C. Sachs, Heinz Günter Brokmeier, Sang Bong Yi, G. Servos, H.G. Hartwig
Abstract: In this study we present experimental investigations on the microscopic structure, constituent phases, and crystallographic textures of the exoskeleton of three types of decapod crustaceans, namely, lobster, crab, and horseshoe crab. The carapace of such animals is a biological multiphase nano-composite consisting of an organic matrix (crystalline chitin and non-crystalline proteins) and biominerals (calcite, phosphate). The synchrotron measurements of the crystalline chitin and of the biominerals which are embedded in the chitin-protein matrix (in case of lobster and crab) reveal strong textures. The horseshoe crab does not seem to contain notable amounts of crystalline minerals. The Debye-Scherrer images of the lobster specimen suggest that the biominerals form clusters of crystals with similar crystallographic orientation. TEM images support this suggestion. The crystallographic texture of the chitin is arranged with its longest cell axis parallel to the normal of the surface of the exoskeleton.
Authors: G. Langelaan, S. Deprez, Ignaas Verpoest, Paul van Houtte
Abstract: The orientation distribution of fibres (morphological texture) in a composite is very important in determining the properties of the material. Therefore, methods which can provide quantitative descriptions of the morphological texture are essential. One approach to determining the morphological texture function (MTF) is to measure the orientation distribution of the crystals in the fibres. Since many types of reinforcing fibres are crystalline and textured (i.e. carbon fibres, whiskers, etc.) this approach may be interesting for commercial/industrial applications. For this technique to be applied, the crystallographic texture intrinsic to the fibres must be determined and subsequently measurements of the crystallographic texture should be made in the composite. The morphological texture can then be calculated by a deconvolution of the composite texture with the fibre’s intrinsic texture. In this paper, morphological textures are determined in woven fabrics made from carbon fibres embedded in a polymer matrix. Straight fibres removed from the fabric serve as the reference material for the deconvolution. It is demonstrated that this technique is applicable and can resolve the orientation distribution to an accuracy greater than is needed for determining the elastic properties.
Authors: Jong-Kook Kim, Moo Young Huh, Kwang Koo Jee, Olaf Engler
Abstract: A clad composite of five plies of STS/Al/Al/Al/STS was produced by roll-cladding at 350°C from ferritic stainless steel (STS) and aluminum (Al) sheets. In order to clarify the strain state during roll-cladding, the evolution of textures at different through-thickness layers in the roll-clad composite was investigated. Because the deformation mainly occurred in the Al sheets during roll-cladding, the present investigation was focused on the Al sheets. In the STS/Al/Al/Al/STS composite, the mid Al sheets between STS and center Al displayed pronounced texture gradients with shear textures and plane strain rolling textures, while the center Al sheet depicted a plane strain texture throughout the whole sheet thickness. Simulations with the finite element method (FEM) disclosed that a large variation of shear strain rate during roll-cladding led to the formation of these texture gradients.
Authors: Wen-Hai Ye, Hans Georg Priesmeyer, Heinz Günter Brokmeier
Abstract: Cu-Nb composites are characterized by some special properties, which were discussed since a long time by many different authors [1, 2, 3, and 4]. For manufacturing linear accelerator units it is a great advantage that Cu-Nb don’t form intermetallic compounds. One of the basic questions during application is the influence of the thermal expansion of copper and niobium. Thermal expansion of Cu-Nb was widely discussed by Nadeau and Ferrari [5]. Our research program consists of investigations on Cu50%-Nb50% composites and on Cu-Nb tubes, which on one hand have different textures and on the other hand the grain boundaries are much different in the composite with a curling microstructure and in co-extruded tubes. The present paper will concentrate on thermal stresses and the texture behavior in the temperature range 4K -1273K.
Authors: Vladimir Serebryany, Sergey F. Kurtasov, T.I. Savyolova
Abstract: Influences of an X-ray experimental texture plan and of pole figure primary errors on the accuracy of the ODF coefficients are discussed. A modified harmonic method, which is a statistical method of ridge estimates, has been used for ODF restitution from pole figures. The plan of measurement of the pole figures was analysed on the basis of minimization of the primary experimental errors and the errors of the ODF restitution method. Principles of the optimum texture plan construction for hexagonal metals (magnesium example) and for the URD-6 texture diffractometer are considered.

Showing 251 to 260 of 260 Paper Titles