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Talks and Poster Presentations (with Proceedings-Entry):

D. Canelo Yubero, G. Requena, C. Poletti, F. Warchomicka, H.P. Degischer:
"Load partition and microstructural evolution during hot deformation of Ti-alloys";
Talk: Euromat 2011, Montpellier; 09-12-2011 - 09-15-2011; in: "European Congress on Advanced Materials and Processes", (2011), Paper ID D11-O-2-4, 1 pages.



English abstract:
Synchrotron X-Ray Diffraction (SXRD) has become an essential tool to study either the averaged internal stresses in the bulk or the microstructural changes with time of multiphase materials. Its high penetration, high flux and short acquisition times in comparison with laboratory X-ray diffraction allow to characterize the phase evolution in short time tests. The present work shows in situ investigations using this technique to follow the evolution of both internal strains and microstructure during tensile tests of Ti6Al6V2Sn (Ti662) at different temperatures in argon atmosphere. A monochromatic beam with a 2D-Detector was used for this purpose. Ti662 alloys were produced by means of two different processing routes, i.e., powder metallurgy (PM) and ingot (ING). PM material exhibits lamellar microstructure and the ING material has globular microstructure provoked by the pre-forging process. Analyzing the different crystallographic planes in the load direction, strains in α-phase are always higher compared with those in the β-phase. For the PM material, α-phase shows maximum strains at the maximum tensile stress and subsequently softens due to damage in the samples, while the ING material exhibits plastification once the maximum tensile stress is reached. The orthogonal direction exhibits the Poisson´s effect with negative strain values for all the materials and tests. The evolution of the microstructure is analyzed by processing the Debye Scherrer rings for different crystallographic planes of the α and β phases. The PM material exhibits subgrain formation in the β-phase, observed as a spreading of the spots. Rotation of α-phase can be determined by a splitting of the spots. In ING samples this effect is not observable due to the fine microstructure. Electron BackScatter Diffraction (EBSD) before and after the tensile tests confirm these microstructural changes showing the subgrain formation in the β-phase and the lattice rotation of α grains with increasing strain.

Keywords:
Synchrotron Diffraction, Ti-alloys, Internal strains, Hot deformations, In situ tensile test

Created from the Publication Database of the Vienna University of Technology.