THE EFFECT OF SPECIMEN’S GEOMETRY ONTHE UPSETTING TEST OF THE NANOSTRUCTURAL AL-6086 ALLOYMATERIAL PRODUCED BY EQUAL- CHANNEL ANGULAR PRESSING

الملخص

The increasing interest in bulk nanostructured materials (NSM), processed by severe plastic deformation technique (SPD), comes as a result of their physical and mechanical properties. The most common plastic deformation technology used in producing the bulk ultra-fine- grained (UFG) materialsis known as the equal-channel angular pressing (ECAP), typically in the sub micrometer or nanometer range by applying a very high plastic strain to the material. The large plastic shear deformation could be achieved by forcing the material to change its direction by 90º (intersection angel between two channels). A commercial Al- Mg-Si alloy (6082) is deformed by ECAP in order to producing bulk nanostructured materials with a high length to diameter ratio as 15-16 using route C technique up to eight passes. During the upsetting of ECAP products (one, four and eight passes), the anisotropy phenomenon induced by the ECAP technology has led to an asymmetrical bulging/buckling of the specimen. In this work, three sets of the upsetting specimen's geometry (height / diameter ratio) of three ECAP passes specimens are usedin the investigation of the anisotropy phenomenon and in the comparison with a conventionalone. The results show that the number of ECAP passes and the height/diameter ratio of the upsetting specimens have significant effect on the anisotropy of the ECAP material. Thisanisotropy is reduced by controlling the height/diameter ratio of the upsetting specimens.