INFLUENCE OF ECAP ROUTES ON MECHANICAL PROPERTIES OF A NANOCRYSTALLINE ALUMINIUM ALLOY

Equal-Channel Angular Pressing (ECAP) is an effective tool for producing ultra fine grained materials. In repeated application of ECAP, the rotation of the sample along the longitudinal axis of the billet allows to carry out different routes of deformation. The applied route has a strong influence on the texture, microstructure and mechanical behaviour of ECAP processed metals. In the present study ECAP was successfully applied to produce ultra fine-grained microstructure in a commercial Al-Mg-Si alloy (Al 6082). The mechanical investigations of the ECAP deformed specimens revealed that after 4 ECAP passes the material had a very high strength but a significantly decreased ductility. Further ECAP processing to 8 passes by route C increased ductility dramatically and strength slightly. The diameter ratio of the ellipse shaped cross-section of the compressed specimens was the highest for the sample deformed by route C for eight passes. This indicates that the anisotropy of the structure of ECAP deformed materials may play an important role in achieving good ductility. The quality of the ultra-precision finished surface of the processed sample improved dramatically after eight passes