Users and Staff
M.A. Gibbs, K.T. Hartwig, R.E. Goforth, Department of Mechanical Engineering, Texas A&M University
E.A. Payzant, HTML, Oak Ridge National Laboratory
Equal Channel Angular Extrusion
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- Equal channel angular extrusion (ECAE) is a recently developed process in which the deformation occurs by simple shear
- Multiple pass ECAE allows for large amounts of deformation and corresponding microstructure development without changing the cross sectional area
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Samples Were Prepared Using Different ECAE Processing
- billets 1 inch square by 6 inches long were machined from cast and subsequently hot rolled iron received from Magnetics International, Inc.
- these billets were extruded at room temperature with a ram velocity of 0.02 inch/sec
- a strain intensity of 1.17 was developed per extrusion pass
- four different processing routes were investigated:
- extrusion in same direction for each pass
- alternate rotation of billet between 0oand 90oorientations
- alternate rotations between 0 and 180o orientations
- rotation by 90o for each subsequent pass
Texture was Determined Using X-ray Diffraction
- samples for texture measurement were cut from the center of the planes of each billet and polished to a metallographic finish
- a four axis PTS goniometer permitted the necessary sample rotations to measure pole figures
- Cu radiation yields a high fluorescence with iron samples, and Cr radiation was too sensitive to surface artifacts, consequently Mo Ka radiation was utilized to better assess the bulk texture
- three pole figures (110), (200), and (211) were obtained for each sample
- pole figure results were analyzed using the Preferred Orientation Package - Los Alamos (popLA) software
Route A: Same orientation each pass
2 passes
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7 passes
Processing via Route A develops a texture very similar to a sheet texture.
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Summary
- Multiple pass ECAE allows for large amounts of deformation, microstructure development, and texture development
- Utilizing X-ray diffraction pole figures, it was demonstrated that different ECAE processing routes may be utilized to develop sheet textures, fiber textures, or torsion textures in bcc iron
- These textures are comparable with those produced by conventional rolling, drawing, and twisting processes
- Additional work is in progress to evaluate the effect of these ECAE processing routes on textures in Fe-3Si alloys and on tantalum.
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