The effects of homogenization process after heat treatment properties in AA 7075 aluminum alloy

In this study, the changes in the hardness and microstructures of the non-homogenized and homogenized AA7075 alloy after T6 heat treatment were investigated. The disc removed from the cast AA7075 ingots within the scope of the study was divided into two parts and one of these parts was homogenized at 480 ° C for 5 hours, and the other was not. Subsequently, solution treated and quenching processes (T4) were applied to both sample groups at 530ºC 90 min. A total of 22 samples, 20mmx20mm in size, were prepared from non-homogenized, homogenized and T4 treated. Sample 1 is the sample that has undergone no treatment (as-cast alloy, homogenized) and we use as the reference sample. There are 11 samples from one group and 3 samples with different temperatures and 3 different ages in this solution. There are also 11 samples from the homogenized group. Aging was applied at three different temperatures (160ºC, 170ºC and 180ºC) and at different times (4 h, 6 h and 8 h). Metallographic surface preparation process was applied to the samples and the prepared samples were examined by microscope and their images were recorded. Afterwards, these samples were examined by optical microscope (OM) and scanning electron microscope (SEM) and chemical analysis of the phases were done by energy dispersive x-ray spectral analysis (EDS, x-ray energy dispersive spectroscopy). Finally, Vickers hardness values were measured on polished samples. By examining these findings, the microstructure and hardness of non-homogenized and homogenized samples after aging were evaluated and the effects of the homogenization process were revealed. As a result; with the homogenization process, the microstructure was changed significantly and the dendritic structure was eliminated. Accordingly, there was a decrease in hardness value. Since the subsequent solutionizing process also acts as a kind of homogenization process, microstructure differences and accordingly hardness differences disappeared as a result of water quenching and aging processes. Samples that non-homogenized and homogenized have similar microstructural and hardness properties. For this reason, it is determined that homogenization process does not have a significant effect on microstructure and hardness properties after heat treatment.