Materials Science Forum Vols. 702-703

Abstract: Texture of Al alloy is affected to the formability and mechanical properties. In this paper, it was studied that the change of texture and formability of AA 1050 Al alloy sheets which were asymmetrically rolled. Asymmetrically rolled Al sheets showed that the distorted rotated cube texture, {001}, γ-fiber, ND// and {120} and {120} components were increased. The change of texture components after the asymmetrical rolling could be affected to the variation of plastic strain ratios of the asymmetrically rolled AA 1050 Al alloy sheets.

Abstract: Uniaxial compression tests were conducted on Al-2.3mass%Cu and Al-4.6mass%Cu alloys under strain rates and temperatures ranging from 1.0×10^-4s^-1 to 5.0×10^-2s^-1 and 723K to 803K, respectively. Texture measurements reveal that main component of the fiber texture changes from {001} + {011} to {001} depending on the deformation conditions. EBSD measurements reveal that grain structure separates into large grains without subgrains and small and large grains with subgrains after the deformation at 803K under a strain rate of 5.0×10^-2s^-1 up to a strain of -1.0 in Al-4.6massCu alloy.

Abstract: Formation process of textures in AZ80 is investigated on polycrystal specimens with different initial textures by plane strain compression deformation at 673 K and 723 K with strain rates between 5.0×10^-4s^-1 and 5.0×10^-2s^-1. Three kinds of specimens were taken out from the extruded bars with (direction of the extrusion) fiber texture by changing the geometrical relationship with the extrusion direction. In the case of the specimen having parallel to the compression direction before deformation, the initial fiber texture gradually transformed into several orientations with increasing strain at 723K with a strain rate of 5.0×10^-2s^-1. oriented grains, which was not seen in the pole figures before deformation appeared after the deformation up to -1.0 in true strain. The other two kinds of specimens have compression directions perpendicular to direction. The textures after deformation of these two kinds of specimens also consisted of several components. Some of them are common among the three kinds of specimens and the others are retained components of the initial texture.

Abstract: Magnetically hard Fe-Cr-Co-based alloys are distinguished by their good ductility, excellent magnetic properties and low cost. Their superior magnetic properties are obtained by magnetic treatment and multistage tempering, which results in spinodal decomposition of the solid solution into the isomorphous α1 and α2 phases. However, the α1+α2 microstructure causes a reduction in the plasticity and strength of the material. It can often be advantageous for permanent magnets to maintain fine magnetic properties throughout their volume along while retaining good mechanical properties only in the subsurface layer. To improve the mechanical properties of the latter, FeCr30Co8 samples were deformed in tension combined with torsion. Loading was applied at 750°C, which ensured that the conditions for superplastic deformation were fulfilled. Here, we present the results of microstructure investigations of the samples treated in the aforementioned manner. Observations of the longitudinal section of the samples showed the formation of a gradient microstructure with the maximum grain refinement in the surface layer and the characteristic rotation of the elongated α phase grains from positions nearly perpendicular to the tension axis at the surface to positions tilted at approximately 45º to the tension axis inside the material. Deformation at superplastic conditions also activated precipitation of the σ intermetallic phase, particularly in the areas of highest deformation. The refinement of the microstructure and precipitation of the σ-phase resulted in a significant increase in hardness at the surface of the FeCr30Co8 samples.

Abstract: In the present work, 5086 Al alloy is subjected to single and multi pass friction stir processing (FSP) to modify microstructure and mechanical anisotropy. The processing is carried out at constant rotation speed of 1025 rpm and different traverse speeds of 30 mm/min and 50 mm/min with and without cooling. Mechanical anisotropy is evaluated in terms of normal and planar anisotropy by performing tensile test in 0, 45 and 90o direction to processing direction. Material processed using multi pass FSP at 30 mm/min is showing lower planar anisotropy as compared to base material. The mechanical anisotropy property is correlated with the development of micro texture.

Abstract: A Ni-5.7%Cr-25.2%W (wt%) alloy was deformed by cold rolling in different reduction conditions (50%, 70%, and 90%) and then annealed under hydrogen atmosphere. Microstructure and texture evolutions were analyzed using Electron BackScattered Diffraction (EBSD). Orientation Distribution Functions (ODFs) and stored energy were calculated from neutron diffraction measurements. A strengthening of the α-fiber texture was observed after 90% cold rolling and a homogenous microstructure was obtained after annealing at 900°C.

Abstract: The texture, microstructure, plastic strain ratio r value, elongation, strain hardening index n, the value of cupping test I_E, and the correlation between r value and the other formability indices of two automotive aluminum alloys sheet 6016 and 6181, and commercial pure aluminum sheet were investigated. The results showed that the recrystallization textures of three aluminum alloys sheet are similar to each other, which mainly contain cube component. However, the r and n value, elongation, and I_E of three aluminum alloys sheet are different from each other evidently, and there is no correlation between texture and r value, and the other formability indices except the n value. The large quantity of second-phase particles in the aluminum alloy matrix has very important effect on both the r value and the formability of aluminum alloy sheet.

Abstract: Even anisotropic superplastic flow, which is a result of an elongated grain shape and texture, can lead to extreme elongations to fracture (superplasticity). Therefore, to identify the mechanisms of deformation present during superplastic flow alone, the effects of the microstructure should be eliminated first. Using an Al 5083 alloy, in which an equi-axed microstructure is present from the beginning, it is shown that grain boundary sliding, accompanied by grain rotations, is the rate controlling mechanism.

Abstract: The changes in texture and microstructure that occur during superplastic deformation (SPD) of a suitably thermo-mechanically processed (TMP) Al alloy AA7010 containing Sc at a temperature and strain rate combination of 475°C, 1.9x10^-2s^-1 have been examined. It is observed that during the early stages of SPD, there is a significant increase in the Brass {110}<112> component as well as a considerable increase in the S {123}<634> component. Whilst, these components gradually decrease leading to the randomization of texture as the SPD process progresses to larger strains. These results are discussed in terms of the nature of the TMP together with significant variations in the number density of Al₃Sc_xZr_1-x dispersoids and percentage recrystallization with strain.

Abstract: Disks of copper samples were produced by High Pressure Torsion (HPT). Specimens for tensile creep experiments were cut from the disks and subjected to creep deformation at 348 K to obtain elongations greater than 30%. Electron backscatter diffraction (EBSD) was used to analyze the texture after HPT deformation and after additional tensile elongation.