Upper-Bound Analysis for Change-Channel Angular Extrusion

Deformation of the material during 90° change-channel angular extrusion (CCAE) process is analyzed using upper-bound theorem. The mathematical model was established which includes the effect of friction between the sample and inner surface of the die, radius of inner and outer corner of the die, and the dead metal zone on the deformation patterns during change-channel angular extrusion deformation process. The model of parameters is explored in relation to the deformation of the material during the change-channel angular extrusion process. Results showed that the extrusion force increased with the increase of extrusion ratio (a2/b2), friction factor m, out corner and the reduce of inner corner. Further directions for progress in upper-bound analysis in change-channel angular extrusion deformation process are outlined.