MEDIUM STRENGTH 7xxx SERIES REGENERATED ALUMINUM ALLOY AND METHOD FOR PREPARING THE SAME

A method for preparing a medium strength 7xxx series regenerated aluminum alloy, comprising:

• a raw material selection and composition design step of providing a primary pure aluminum ingot, a first recycled aluminum alloy, a second recycled aluminum alloy, and a third recycled aluminum alloy, each of the first recycled aluminum alloy and the second recycled aluminum alloy being selected from the group consisting of a 5xxx series recycled aluminum alloy and a 6xxx series recycled aluminum alloy, the third recycled aluminum alloy being selected from the group consisting of a 5xxx series recycled aluminum alloy, a 6xxx series recycled aluminum alloy, a 1xxx series recycled aluminum alloy, a 7xxx series recycled aluminum alloy, and a combination thereof,
• wherein each of the first recycled aluminum alloy, the second recycled aluminum alloy, and the third recycled aluminum alloy contains target alloying elements, and
• wherein amounts of the first recycled aluminum alloy, the second recycled aluminum alloy, the third recycled aluminum alloy, and the primary pure aluminum ingot are calculated based on a predetermined amount of a respective one of the target alloying elements in a medium strength 7xxx series aluminum alloy which has a grade same as a grade of the medium strength 7xxx series regenerated aluminum alloy;
• a purification and refining step of purifying and refining at least one of the first recycled aluminum alloy, the second recycled aluminum alloy, and the third recycled aluminum alloy containing the target alloying elements provided in the raw material selection and composition design step to remove a portion of at least one of the target alloying elements from the at least one of the first recycled aluminum alloy, the second recycled aluminum alloy, and the third recycled aluminum alloy based on the predetermined amount of the respective one of the target alloying elements in the medium strength 7xxx series aluminum alloy, so as to obtain a refined recycled aluminum material containing the target alloying elements, a remaining portion of the first recycled aluminum alloy, the second recycled aluminum alloy, and the third recycled aluminum alloy being an unrefined recycled aluminum material that contains the target alloying elements after the at least one of the first recycled aluminum alloy, the second recycled aluminum alloy, and the third recycled aluminum alloy has undergone the purification and refining step;
• a melting step of melting the primary pure aluminum ingot provided in the raw material selection and composition design step, the unrefined recycled aluminum material, and the refined recycled aluminum material obtained in the purification and refining step into an aluminum alloy melt containing the target alloying elements, an amount of a respective one of the target alloying elements in the aluminum alloy melt being not greater than the predetermined amount of the respective one of the target alloying elements in the medium strength 7xxx series aluminum alloy;
• an alloy composition conditioning step of adjusting the amount of the respective one of the target alloying elements in the aluminum alloy melt obtained in the melting step to fall within the predetermined amount of the respective one of the target alloying elements in the medium strength 7xxx series aluminum alloy, so as to obtain a conditioned aluminum alloy melt, the first recycled aluminum alloy, the second recycled aluminum alloy, and the third recycled aluminum alloy in the conditioned aluminum alloy melt being present in an amount not lower than 75 wt %, based on a total weight of the conditioned aluminum alloy melt as 100 wt %;
• and
• a casting step of subjecting the conditioned aluminum alloy melt obtained in the alloy composition conditioning step to a casting treatment, so as to obtain the medium strength 7xxx series regenerated aluminum alloy containing the predetermined amount of the respective one of the target alloying elements.