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Li X.,Central South University | Duan Y.L.,Central South University | Xu G.F.,Central South University | Xu G.F.,State Key Laboratory of Powder Metallurgy | And 4 more authors.
Materials Characterization | Year: 2013

This work presents the use of a mechanical testing system and the electron backscatter diffraction technique to study the mechanical properties and twinning systems of cold-rolled commercial purity titanium, respectively. The dependence of twinning on the matrix orientation is analyzed by the distribution map of Schmid factor. The results showed that the commercial purity titanium experienced strong strain hardening and had excellent formability during rolling. Both the 112̄2 <112̄3̄> compressive twins and 101̄2 <101̄1̄> tensile twins were dependent on the matrix orientation. The Schmid factor of a grain influenced the activation of a particular twinning system. The specific rolling deformation of commercial purity titanium controlled the number and species of twinning systems and further changed the mechanical properties. © 2013 Elsevier Inc. Source


Li X.,Central South University | Xu G.F.,Central South University | Xu G.F.,State Key Laboratory of Powder Metallurgy | Peng X.Y.,Central South University | And 5 more authors.
Materials Science and Technology (United Kingdom) | Year: 2013

In this work, twinning systems of tensile deformed commercial purity titanium were studied using the electron backscatter diffraction technique and Schmid factor analysis. The dependence of twinning on the matrix orientation was determined by the distribution map of the Schmid factor. The results showed that both {112̄2} 〉112̄3̄〈 compressive twins and {101̄2} 〉101̄1̄〈 tensile twins are dependent on the matrix orientation. Twins were activated in the grains with large values of twinning Schmid factor. The critical shear stress and Schmid factor of a grain determined the activation of a particular twinning system. © 2013 Institute of Materials, Minerals and Mining Published by Maney on behalf of the Institute. Source


Li X.,Central South University | Peng X.-Y.,Central South University | Duan Y.-L.,Central South University | Zhang L.-G.,Zunyi Titanium Industry Co. | And 3 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2013

The morphologies, roughness and phase structure of hardened layer of commercial purity titanium (CP-titanium) after thermal oxidation at 600, 700 and 800°C were investigated by AFM, SEM and XRD. The diffusion mechanism, formation of oxygen-diffusion zone and stratification during the thermal oxidation treatment were analyzed. The results show that the roughnesses of hardened layer increase and the oxide particles grow up continually with the increase of oxidation time and temperature, and the main phases are TiO2, Ti2O, Ti3O and Ti6O. The oxidation process of CP-titanium is that oxygen atom passes the gaseous phase/oxidation film and oxidation film/metallic matrix. The structure and property of oxidation film change and lead to stratification due to the acceleration of oxidation reaction and the decomposition of oxidation film. Source


Xu G.,Central South University | Xu G.,State Key Laboratory of Powder Metallurgy | Cui X.,Central South University | Peng X.,Central South University | And 4 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2013

The annealing heat treatment of commercial-purity titanium (CP-Ti) was investigated by scanning electron microcopy (SEM), electron backscatter diffraction (EBSD) technique and orientation distribution function (ODF). It is concluded that two stages can be depicted during the primary recrystallization. The first stage is completed at 500°C in about 60 min, when about 25% of the material recrystallizes with an orientation change. The second stage is completed from 60 to 360 min, when a large part of the material (about 75% of the material) recrystallizes without any orientation change, suggesting in situ recrystallization. The changes in texture are more pronounced at the beginning of the grain growth process. Over long-term heat treatments, the texture evolves much more slowly. The wide peak area centered by {0°, 30°, 30°} is enhanced, while the orientation near {0°, 40°, 50°} is decreased. Copyright © 2013 Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved. Source

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