Bending may or may not strengthen the aluminum alloy. In other cases, the reverse is true. Bending can also lead to the weakening of aluminum alloys. This is dependent on conditions to which the metal is exposed to. If they’re extreme, you can be certain the metal will be weakened.
On the flipside, the right conditions will make the aluminum stronger if exposed to bending. Therefore, the question of strengthening or weakening aluminum is subject to the environment you expose the metal to.