MECHANICAL PROPERTIES AND MICROSTRUCTURE OF AA 1050 PROCESSED BY ECAP CORRELATED TO THE STRAIN TENSOR

Flow pattern during ECAP was investigated by pressing two halves samples with marked grid through the ECAP die. Further experiments were conducted by pressing AA 1050 samples up to 12 passes using two different processing routes, with each route has its distinct succession of sample rotations between consecutive passes. Evaluation of the mechanical properties was done through tensile testing and Vickers hardness. The results ascertained the achievement of ultra-fine grain size after ECAP with average grain size of 0.68 microns after .12 passes, with 60% of the examined grain structure exhibited high angle grain boundaries. Consequently, a great strengthening was achieved with an increase in the 0.2% proof strength with a factor of more than 6, and the UTS with a factor of more than 3 after 12 passes compared to the annealed state. The accumulated strain tensors were also established to examine the correlation between the strain values in the tensors and the shape of a deformed cubic element The tensors were also calculated in correlation with the evolution of strength. Theoretical calculation of the plunger forces needed for the ECAP process was also derived and compared to the experimental values.