Strain uniformity through equal channel angular extrusion

Abstract

The objective of this work is to characterize the processing effects of equal channel angular extrusion (ECAE) on aluminum 6063, copper I 10, and filamentary Cu/NbTi composite superconductor. The major objective of this study is to measure strain uniformity throughout the workpiece after ECAE processing. Other objectives include the determination of the size and width of the shear zone, determination of the depth of the surface affected zone, and comparison of the magnitude of the experimental strain and the angle of element distortion with first order calculations. Several testing procedures have been used throughout this research project. Hardness measurements were used to measure the level of plastic deformation. Square grids were scribed on a split billet in order to record the flow of the metal throughout an ECAE extrusion. An aluminum billet with brass wire inserts oriented perpendicular to the extrusion direction were used to show the deformation of material through multiple extrusions. Electrical resistivity measurements were used to monitor the level of strain throughout the billet. The angle of shear of a material element after a single extrusion is measured to be 63.63'. This compares well with theory (63.43'). Hardness and resistivity measured across a billet extruded one pass through ECAE vary by less than 1%. The surface affected zone along the bottom of a billet is determined to be less than 12% of the billet width. The width of the shear zone varied from one-tenth to three-tenths of the billet height.