Texture development of BCC metals processed by equal channel angular extrusion /
The objectives of this research were to characterize the texture, quantify microhardness, characterize microstructure, praise mechanism for texture development, and compare texture type and intensity to conventional processes of four BCC metals (iron, iron-3%silicon, tungsten, and tungsten heavy a...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728408471&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The objectives of this research were to characterize the texture, quantify microhardness, characterize microstructure, praise mechanism for texture development, and compare texture type and intensity to conventional processes of four BCC metals (iron, iron-3%silicon, tungsten, and tungsten heavy alloy) processed using equal channel angular extrusion routes A,B,C, and C'. Route A processing yielded an elongated grain structure and increased hardness with each subsequent pass. Texture development along the longitudinal plane produced orientations similar to rolling with intensity levels lower than rolled samples at equivalent strain. Route B processing yielded an elongated grain structure through two passes; grain structure was undetectable by optical microscopy at higher passes. Microhardness increased with each subsequent extrusion pass. Texture development along the transverse plane produced an incomplete tuber texture similar to wire drawn materials. Comparison of texture intensity to drawn samples at equivalent strain yielded lower intensities in the Route B processed material. Route C processing produced an equiaxed grain structure after an even number of extrusion passes, and microhardness increased as the number of extrusion passes increased. Texture development along the flow plane yielded components of torsional or shear textures. Route C' processing produced an undetectable microstructure by optical microscopy after four and eight extrusion passes with an increase in microhardness with the number of extrusion passes. Texture development along the transverse plane yielded components of an incomplete tuber texture with intensities lower than drawn wire at equivalent strain. Simple shear deformation via ECAE produces two-fold rotational symmetry about the flow plane nodal and a mirror plane within the flow plane. Simple shear textures developed by ECAE processing are rotated 15° about the longitudinal plane as compared to conventional simple shear textures. This rotation is a result of strain path change associated with multiple extrusion passes of ECAE not present in conventional simple shear deformation. Texture intensities of ECAE processed samples versus conventional processed samples (rolling and drawing) are lower due to rigid body rotations associated with simple shear deformation. The ability to alter shear plane and shear direction with multiple passes of ECAE yields several textures depending on the processing route. |
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| Item Description: | Vita. "Major Subject: Mechanical Engineering". |
| Physical Description: | xx, 188 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 182-185). |