Equal channel angular extrusion
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In industrial metalworking, Equal channel angular extrusion (ECAE) is an extrusion process, developed in 1973 in the Soviet Union. The technique is able to refine the microstructure of metals and alloys, thereby improving their strength according to the Hall-Petch relationship.
ECAE is unique because significant cold work can be accomplished without reduction in the cross sectional area of the deformed workpiece. In conventional deformation processes like rolling, forging, extrusion, and drawing, strain is introduced by reduction in the cross sectional area. ECAE produces significant deformation strain without reducing the cross sectional area. This is accomplished by extruding the work piece around a corner. For example, a square cross section bar of metal is forced through a channel with a 90 degree angle. The cross section of the channel is equal on entry and exit. The complex deformation of the metal as it flows around the corner produces very high strain. Because the cross section remains the same, a work piece can be extruded multiple times with each pass introducing additional strain.
Die design is critical because of the large forces required.
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