Distribution Characteristics of In-Grain Misorientation Axes in Cold-Rolled Commercially Pure Titanium and Their Correla
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INTRODUCTION
MUCH effort has been directed toward deconvoluting the slip and twinning mechanisms of deformation in hcp metals, as is well documented in review articles.[1–3] This work is of prime importance not only for the fundamental understanding of generalized plasticity of hcp metals but also for alloy or process design strategies in the development of lightweight structures based on Ti and Mg. Despite this work, the deformation modes responsible for the accommodation of strain imposed on polycrystals and the formation mechanism of deformation textures have not been entirely described. The trade-off is between accurately identifying the active slip modes while sampling a statistically valid number of grains to sufficiently large strains. For example, surface trace analysis reveals the active slip or twinning modes[4–11] but is applicable only to single crystals (or very coarse-grained polycrystals), which are deformed by uniaxial loading to a limited strain. The Burgers vector determination technique based on transmission electron microscopy (TEM) permits the identification of active slip modes in deformed polycrystals,[12–15] but substantial time is required to analyze a sufficient number of grains, and the technique is restricted to materials deformed to a small strain because of the Y.B. CHUN, Research Fellow, and C.H.J. DAVIES, Associate Professor, are with the ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, Clayton, Victoria 3800, Australia. M. BATTAINI, Materials Engineer, is with the Advanced Materials Group, AECOM, Fortitude Valley, Queensland 4006, Australia. S.K. HWANG, Professor, is with the School of Materials Science and Engineering, Inha University, Nam-gu, Incheon 402-751, South Korea. Contact e-mail: skhwang2@ gmail.com Manuscript submitted March 6, 2010. Article published online October 1, 2010 METALLURGICAL AND MATERIALS TRANSACTIONS A
difficulties in determining the Burgers vector and glide plane of complicated dislocation structure introduced by a large strain. A limitation common to both approaches is that the number of grains accessible is usually quite small, which may introduce an uncertainty in drawing general conclusions on the deformation mechanism in hcp polycrystals. For pure Ti single crystals deformed at room temperature, for example, Paton and Backofen[16] reported hc + ai slip on the f1011g plane, whereas hc + ai slip on the f1122g plane was observed by Minonishi and Morozumi.[17] There have been some attempts to determine statistically-averaged information on the deformation mechanism of hcp metals using the X-ray[18,19] or neutron[20–22] line broadening technique, but this technique is unable to provide information on the plasticity of individual grains. Since the overall plastic behavior of polycrystals can be considered as an integrated plastic response of individual grains composing the material, it is necessary to study how individual grains with different orientations in polycrystals respond to externally imposed s
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