Investigation of Microstructural and Hardness Changes of AA7075 Alloy Processed by ECAP

This study aims to examine the change in microstructural and hardness values AA7075 aluminum alloy, which is frequently preferred in the aviation industry by applying the Equal Channel Angular Pressing (ECAP) method. ECAP method, one of the plastic deformation methods, has been successfully carried out by applying 0.025mm/sec pressing speed and 200°C temperature for a different route (A, Bc, C) and the different number of passes (2, 4, 8). The characterization of the aluminum alloy obtained by applying ECAP process was carried out by optical microscope (OM), X-ray diffraction (XRD), and scanning electron microscope (SEM) analysis. Hardness tests have been applied to examine the mechanical properties of the material. The microstructures of the materials obtained as a result of the application were examined. It was observed that precipitation occurred in the AA7075 alloy depending on the applied temperature, pressing, and grain breakage. Moreover, it is seen that the grain size of the materials produced by the ECAP method has been reduced, and consequently the strength of the material increases. As a result of the ECAP process, it was seen that the existing phases were α-Al, n-MgZn2, S-Al2CuMg, and Al7Cu2Fe. The grain size of 288.4 nm obtained after 8 repeated passes using the Bc route was the smallest grain size obtained.