Zirconium-strontium composite micro-alloyed high-toughness corrosion-resistant low-silicon-content aluminum-silicon-copper cast aluminum alloy and preparation method

The invention relates to a Zr-Sr composite micro-alloyed high-toughness corrosion-resistant low-Si-content Al-Si-Cu cast aluminum alloy and a preparation method thereof. The aluminum alloy is characterized by being mainly prepared from the ingredients in percentage by mass: 3.55% to 3.65% of silicon, 1.39% to 1.43% of copper, 0.397% to 0.403% of zinc, 0.271% to 0.272% of zirconium, 0.0083% to 0.0085% of strontium (Sr) and the balance of aluminum and a small amount of impurity elements. The preparation method sequentially comprises the steps: (1) melting pure Al and Al-Si intermediate alloy, then, heating the temperature of the melt to 850 DEG C, then, sequentially adding intermediate alloys, carrying out melting, and then, adding pure Zn; (2) regulating the temperature to 750 DEG C after all the intermediate alloys and metals are melted, not escaping gas, carrying out standing, carrying out heat preservation, then, removing slag, and pouring the melt in a metallic die, which is preheated to the temperature of 300 DEG C, for ingot casting. According to the aluminum alloy and the preparation method thereof, the aluminum alloy is dense in cast structure, and proven by actual measurement, the cast alloy has the room-temperature notch-free impact toughness average value of 35.95J/cm .