Method For Manufacturing Billet And Aluminum Alloy Extruded Material

A method for manufacturing a billet comprising,

• melting an aluminum alloy at a temperature within a range of 740° C. to 780° C. and then casting the billet at a solidification rate of 5 ° C./sec or higher, the aluminum alloy including by mass:
• Zn:
• 6.0% to 8.0%, Mg:
• 1.0% to 2.0%, Cu:
• 0.10% to 1.0%, Zr:
• 0.10% to 0.25%, and Ti:
• 0.005% to 0.05%;
• being allowed to further contain Si:
• 0.01% to 0.25% and Fe:
• 0.10% to 0.40%;
• containing Mn:
• 0.004% to 0.4% and Cr:
• 0.05% or less;
• a total of [Fe+Mn+Cr+Zr] being within a range of 0.20% to 1.10%;
• and a balance being Al and inevitable impurities,
• wherein as a raw material, a total of 30 mass% or more of a recycled material including scrap collected from a city and offsets or chips generated in manufacturing a product is contained, and
• homogenizing the billet at a temperature within a range of 470° C. to 540° C. and then cooling the billet at a cooling rate of 50 ° C./hr or higher.