Microband formation in cyclic extrusion compression of aluminum

Abstract

Abstract The influence of very large deformations on the properties and microstructures of Al99.95 and Al99.992 is investigated. The very large deformations are imposed by the cyclic extrusion-compression (CEC) method, which combines extrusion and compression processes. It is found that above true strains of 4 and 8 respectively, the compression proof stresses of Al99.992 and Al99.95 stabilize. The property stabilization appears to result from the increasing incidence of microbands which leads to the final constancy of the microstructure parameters. The homogeneous chess-board like microstructure forms during the deformation by the CEC method, as the result of rearrangement of microstructure by the mutually crossing microbands leading to the final dominance of persistent macro shear bands. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.Retudiesumetudie- On a etudie linfluence de tres grandes deformations sur les proprietes et la microstructure de lAl 99.95 et de lAl 99.992. De tres grandes deformations sont imposees par la methode dextrusion-compression cyclique (CEC), qui combine des processus dextrusion et de compression. Au-dela de deformations reelles de 4 et 8 respectivement, les limites apparentes delasticite sous compression de lAl 99.992 et de lAl 99.95 se stabilisent. Cette stabilisation de la propriete a lair de resulter de laugmentation de loccurrence de micro-bandes, ce qui mene a la constance finale des parametres de microstructure. La microstructure homogene a apparence dechiquier se forme lors de la deformation par la methode CEC, comme resultat du rearrangement de la microstructure par les micro-bandes qui sentrecroisent mutuellement, menant a la domination finale de bandes persistantes de macro-cisaillement.