Chromium-bearing Al-Mg-Si aluminum alloy and preparing technology thereof

The invention discloses a chromium-bearing Al-Mg-Si aluminum alloy and a preparing technology thereof. The content of the main elements of Mg, Cu and Si of the alloy is the same as those of 6463 alloy; the content of the element Cr is changed; and the function of the element Cr in the homogenization process is mainly studied. Intermediate alloy with 99.99 weight percent of high-purity aluminum, 99.99 weight percent of high-purity copper, 99.97 weight percent of industrial pure magnesium, 20 percent of aluminum-silicate and 5 percent of aluminum-chromium is adopted as the alloy. According to the nominal composition of the alloy, three kinds of alloy with the content of the element Cr being 0.1 percent, 0.2 percent and 0.3 percent is prepared. A medium-frequency induction furnace is used for smelting the alloy; zinc oxide is used as a covering agent; hexachloroethane is used for degassing and refining; the casting temperature is 720 DEG C; and a round bar with the diameter of 38.5 mm and the length of 25 mm in size is molded. The tensile strength of the alloy is 187.4-232.8 MPa; the hardness of the alloy is 40.8-57.6 HBW; and the electric resistivity of the alloy is 0.17-0.25 ohmm.