Aluminum alloy for die castings and production process of aluminum alloy castings

Abstract

The present invention provides an aluminum alloy for die castings that has superior castability and corrosion resistance. The amounts of Mn, Fe and Cu contained in the aluminum alloy components for die castings were determined to have a considerable effect on the corrosion resistance of the aluminum alloy. Therefore, the aluminum alloy for die castings of the present invention contains 9.0 to 12.0% by weight of Si, 0.20 to 0.80% by weight of Mg, and 0.7 to 1.1% by weight of Mn+Fe, the Mn/Fe ratio is 1.5 or more, the amount of Cu as impurity is controlled to 0.5% by weight or less, and the remainder is composed of aluminum and unavoidable impurities.

1 . A die casting process comprising:
 providing a mold defining a mold cavity;   closing the mold;   decompressing the mold cavity to a pressure lower than atmospheric pressure;   providing an aluminum alloy comprising 9.0 to 12.0% by weight of Si, 0.20 to 0.80% by weight of Mg, and 0.7 to 1.1% by weight of Mn+Fe wherein the Mn/Fe ration is from 1.5 to 2.43, the amount of Cu as impurity is controlled to 0.5% by weight, the amount of Fe is at least 0.28% by weight and the remainder is aluminum and unavoidable impurities;   filling the mold cavity with a melt of the aluminum alloy after the decompression step.   
   
   
       2 . A die casting process comprising:
 providing a mold defining a mold cavity;   closing the mold;   venting the air inside the mold cavity;   creating an oxygen atmosphere in the mold cavity after the venting step by supplying oxygen to the mold cavity;   providing an aluminum alloy comprising 9.0 to 12.0% by weight of Si, 0.20 to 0.80% by weight of Mg, and 0.7 to 1.1% by weight of Mn+Fe wherein the Mn/Fe ration is from 1.5 to 2.43, weight, the amount of Fe is at least 0.28% by weight and the remainder is aluminum and unavoidable impurities;   filling the mold cavity with a melt of the aluminum alloy after the decompression step.