Aluminum alloy cast ingot and preparation method thereof

The invention discloses an aluminum alloy cast ingot and a preparation method thereof.The preparation method comprises the following steps that S1, a raw material formula is sequentially subjected to smelting, alloying, turning down, refining, slagging-off, standing, degassing and filtering, and an aluminum alloy melt is obtained; s2, the aluminum alloy melt is cast through a crystallizer, and an aluminum alloy cast ingot is obtained; and S3, the temperature of the aluminum alloy cast ingot is reduced to the room temperature in a natural cooling mode, and then the cooled aluminum alloy cast ingot is subjected to saw cutting and face milling in sequence. According to the preparation method of the aluminum alloy cast ingot, the casting internal stress at the beginning of casting can be reduced so as to ensure that the head of the cast ingot cannot crack during casting, and meanwhile, the internal stress of the cast ingot can be fully released, so that the cast ingot cannot generate cracks during saw cutting. 本发