Papers by Keyword: Deformation Texture

Abstract: Asymmetrical rolling was performed by rolling AA 1050 sheets with different velocities of upper and lower rolls. In order to study the effect of roll gap geometry on the evolution of strain states and textures during asymmetrical rolling, the reduction per rolling pass was varied. After asymmetrical rolling, the outer thickness layers depicted shear textures and the center thickness layers displayed a random texture. With decreasing reduction per an asymmetrical rolling pass, the thickness layers depicting shear textures increases. The strain states associated with asymmetrical rolling were investigated by simulations with the finite element method (FEM).

Abstract: Multiple forging (MF) can be used to attain large plastic strains in bulk alloys by successive forging along three orthogonal directions to retain the initial sample shape. An original multiple forging technique enabling 3-D cross forging at constant temperature up to 500°C has been applied to two Al alloys (Al-1%Mn and Al-3%Mg-Sc,Zr). Their rheology, texture and microstructure evolution are compared with those obtained in plane strain compression (PSC). The results are interpreted in terms of slip activity behaviour during both deformation modes. They can also be correlated with the contributions of free dislocations and sub-boundaries.

Abstract: Deformation and primary-recrystallization textures in nickel alloys with some metals (Nb, to 5.4%; W, to 7.4; Re, to 4.1%; Mo, to 9.3%; V, to 10.1%; Mn, to 22.1%; Al, to 12.0% and Cr, to 22.0%) has been studied depending on the content of alloying elements and the rolling temperature. The dependence of the type of recrystallization texture on the component composition of the deformation texture has been established.

Abstract: Thermoelectric oxides consisting of Bi, Pb, Sr, Y and Co are produced by usual sintering method. Uniaxial compression deformation is performed on the oxides under various deformation conditions. Melting temperature is determined by thermal analysis and deformation is conducted close to the melting point. After deformation, density, microstructure, texture and thermoelectric characteristics are experimentally examined. It is found that the oxides plastically deforms at high temperatures, resulting in an increase in density as well as the development of textures. The sharpness of the texture varies depending on deformation temperature, strain rate and the amount of strain. Microstructure observation by SEM elucidates that plastic deformation proceeds without generating severe cracks and all the grains are heavily deformed. Simple examination on the crystal structure suggests that perfect dislocation having small Burgers vector can move on {001} which coincides with the texture results.

Abstract: The aim of this work is to discuss a new non linear intermediate model for large viscoplastic deformations that could predict the texture transition and stress-strain behavior in a range that spans from the upper bound (Taylor) to the lower bound (Sachs or static) estimates. In this model, we introduced a single parameter, f , as a weight function to formulate the proposed intermediate approach which combines the Taylor and Sachs estimates. This formulation leads to an interaction law by the minimization of a tensorial function which depends on the parameter f . For the applications, we focus on the uniaxial tension test. The results for texture evolution in an FCC polycrystal show that a transition between the copper type and brass type textures can be obtained by the proposed non-linear intermediate model.

Abstract: Texture evolution in pure Mg and Mg alloy AZ31 during deformation and annealing was investigated. The poor low temperature ductility can be attributed to both, insufficient shear systems and unfavorable deformation geometry. Static recrystallization was shown to proceed discontinuously despite little texture change. High temperature deformation was accompanied by dynamic recrystallization with similar texture development as during static recrystallization.

Abstract: The paper focuses on the multi-level character of existing or currently developed models for polycrystal deformation. A general multilevel frame is presented, which can be applied to models for the simulation of plastic anisotropy to be implemented in FE codes for the simulation of metal forming processes, or to models for the simulation of deformation textures. A short overview is presented of two-level models ranging from the full-constraints Taylor model to the crystalplasticity finite element models, including the description of a few recent and efficient models (GIA and ALAMEL). Validation efforts based on experimental cold rolling textures obtained for steel and aluminium alloys are discussed. Finally a recent three-level model which also takes the microscopic level (dislocation substructure) is discussed.

Abstract: FCC metals with different stacking fault energy (SFE), namely Al, Cu and Ag have been investigated for the evolution of crystallographic texture during ECAE deformation using Route A. Different materials with different SFE result in their characteristic textures. The results have been analysed on the basis of microstructural features and related established concepts on texture evolution in FCC metals during other deformation modes.