The heat treatment process you tried, which involves exposing the material to 540°C for 50 hours, is a typical homogenization treatment for aluminum alloys. This process is designed to dissolve and redistribute any inhomogeneities in the material, resulting in a more uniform microstructure. However, this treatment may not promote significant grain growth, especially for materials with a fine-grained microstructure.

To promote grain growth in Al 7075, you can try a high-temperature annealing treatment. This involves heating the material to a temperature above its recrystallization temperature and holding it at that temperature for a certain period to allow the grains to grow. The exact temperature and time required for grain growth depend on the specific alloy and microstructure.

In general, the temperature required for grain growth in aluminum alloys is around 550-600°C. The holding time can vary depending on the initial grain size and the desired grain size, but it typically ranges from a few hours to several days. However, it's important to note that high-temperature annealing can also lead to significant changes in the material properties, such as reduced strength and ductility.

It's also worth noting that obtaining centimeter-sized grains in Al 7075 may be challenging due to the fine-grained microstructure of the material.

Mahmoud Elaraby Thank you very much for your insights, I believe that the precipitates are impeding grain growth.

The heat treatment process that can be used to obtain centimeter-sized crystals in hot rolled Al 7075 is called "homogenization" or "annealing".

The homogenization process involves heating the material to a temperature of around 480°C for several hours, followed by a controlled cooling process. This process helps to eliminate any inhomogeneity in the material that may have been caused during the hot rolling process, resulting in a more uniform structure.

After homogenization, the material can be annealed by heating it to a temperature of around 400°C for several hours and then slowly cooling it down to room temperature. This annealing process helps to further refine the structure of the material, which can lead to the formation of larger crystals.

It is important to note that the specific temperature and time parameters for the homogenization and annealing processes may vary depending on the specific properties and characteristics of the Al 7075 alloy being used. Therefore, it is recommended to consult with a materials expert or manufacturer to determine the most appropriate heat treatment process for your specific application.

regards

raghd