Influence of cold extrusion on the microstructure and mechanical properties of an aluminium alloy previously subjected to equal channel angular pressing

Severe plastic deformation processes like the equal channel angular pressing (ECAP) process are currently the subject of extensive investigation and it has been established that ECAP is capable of producing ultrafine grained microstructures in Al alloys. However, practical applications of ECAP process will depend upon the advantages obtained when this process is combined with conventional forming techniques. In the current study, the advantages of the equal channel angular pressing (ECAP) process, when used as an intermediate processing step prior to conventional forming by cold extrusion, have been investigated. ECAP of Al alloy AA 6101 was carried out using a die with 105° die angle for three passes through two different processing routes and these specimens were subsequently processed through conventional cold extrusion. Mechanical property and microstructure data show that improved properties after cold extrusion are heavily dependent upon prior ECAP processing routes. Implications of the results for the processing of ultrafine grained materials are discussed.