The invention discloses a high-Zn, high-Mg and low-Cu ultrahigh-strength
corrosion-resisting aluminum
alloy and a heat treatment method. The
alloy comprises the following components by
mass percentage: 6.5-8.3% of Zn, 2.3-3.0% of Mg, 0.8-1.2% of Cu, 0.1-0.2% of Zr, less than 0.15% of Fe, less than 0.1% of Si, and the balance of Al. A preparation method of the
alloy comprises the steps of blending,
smelting, semi-
continuous casting, homogenizing,
thermoplastic deformation, short time
solid solution, and
ageing heat treatment. For the high-Zn, high-Mg and low-Cu ultrahigh-strength
corrosion-resisting aluminum alloy prepared with the method, the
hardness (HV) is 185-209, the tensile strength sigma b is greater than or equal to 650Mpa, the percentage elongation
delta is greater than or equal to 7%, the pitting resistance is high, the cast
ingot yield is high, and the stress
corrosion resistance is further improved while the
mechanical property is kept after multiple regression reageing treatment. The alloy and the heat treatment method solve the problems that the cast
ingot yield in the existing high-
copper Al-Zn-Mg-Cu ultrahigh-strength
aluminium alloy is low, and the strength,
toughness and corrosion resistance cannot be compromised. The heat treatment method is simple to operate, and the industrial production is facilitated.