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M. H. Goodarzy, H. Arabi, M. A. Boutorabi, S. H. Seyedein, H. Shahrokhi,
Volume 11, Issue 1 (3-2014)

Variation in microstructural features of 2024 aluminum alloy plastically deformed by equal channel angular pressing (ECAP) at room temperature, was investigated by X-Ray diffraction in this work. These include dislocation density dislocation characteristic and the cell size of crystalline domains. Dislocations contrast factor was calculated using elastic constants of the alloy such as C 11, C 22 and C 44 . The effect of dislocations contrast factor on the anisotropic strain broadening of diffraction profiles was considered for measuring the microstructural features on the base of the modified Williamson-Hall and Warren-Averbach methods. Results showed that the dislocations density of the solution annealed sample increased from 4.28×10 12m-2 to 2.41×10 14m-2 after one pass of cold ECAP and the fraction of edge dislocations in the solution annealed sample increased from 43% to 74% after deformation. This means that deformation changed the overall dislocations characteristic more to edge dislocations. Also the crystalline cell size of the solution annealed sample decreased from 0.83μm to about 210nm after one pass of ECAP process at room temperature
J Gholami, M Pourbashiri, M Sedighi,
Volume 12, Issue 4 (12-2015)

Equal-channel angular pressing (ECAP) combined with the Conform process provides a solution for the continuous production of ultrafine-grained materials. In the present study finite element method was executed to investigate the effects of die channel angle and friction on the strain homogeneity and the required torque in ECAP-Conform process. Deformation behaviour of Al 6061 wires was analyzed by using the ABAQUS/Explicit software. Finite element analyses by considering different channel angles (90ᵒ, 100ᵒ and 110ᵒ) and various friction conditions of 0.2, 0.3 and 0.4 were surveyed. The results revealed two distinct trends in which by increasing the channel angle among 90ᵒ to 110ᵒ, the amount of induced plastic strain through the wire reduced about 40%. Also required processing torque was decreased about50%. In addition more homogeneity was observed in higher angle values. The results regarding to equivalent strain, obtained from FE analyses, showed a good agreement with previous studies. Eventually plastic strains and required torque were increased about 8% and 12% when friction coefficient raised between (0.2-0.4).

Bahram Azad, Ali Reza Eivani, Mohammad Taghi Salehi,
Volume 20, Issue 4 (12-2023)

Microstructure evolution and mechanical properties of Zn-22Al alloy after post-ECAP natural/artificial aging were investigated. A homogenization treatment was applied to the casting samples. In addition, after preparing the samples for the ECAP, secondary homogenization treatment was done and then the samples quenched in the water to form a fine grain structure. After 8 passes of ECAP, some ECAPed samples were naturally aged and some ECAPed samples were artificially aged. Natural aging after 8 passes of ECAP showed that Zn-22Al alloy has a quasi-stable microstructure because limited grain growth occurred. Two-phase structure of Zn-22Al alloy prevented excessive grain growth after natural aging. On the other hand, artificial aging after 8 passes of ECAP caused a relatively much grain growth took place. In shorter times of artificial aging, the grain growth rate is faster due to the high surface energy of grain boundaries. On the contrary, as the time of artificial aging increased, the surface energy of grain boundaries decreased, which leads to a decrease in the grain growth rate. In addition, texture evolution was studied after aging artificial. Therefore, the main texture of α and η phases was determined.

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