Preparation method of casting aluminum-coated magnesium alloy composite cast ingot

The invention relates to a preparation method of casting an aluminum-coated magnesium alloy composite cast ingot, and belongs to the field of material process engineering. The method comprises the following steps: (1) continuously welding an aluminum or aluminum alloy plate with thickness of 1-3mm by virtue of an argon-arc welding method to form a precast aluminum plate box with on opening on oneside, wherein the thickness of a clad layer of the aluminum plate accounts for 10 to 20 percent of the total thickness of the aluminum-coated magnesium alloy composite cast ingot; (2) performing mechanical grinding and chemical cleaning on the cavity of the precast aluminum plate box, removing oil stains and oxides from the surface, and placing the precast aluminum plate box in a resistor oven ina protective atmosphere to perform preheating treatment at 200 DEG C; (3) smelting the aluminum alloy core material under gas protection, and controlling the pouring temperature to be between 660 and720 DEG C; and (4) clamping the preheated aluminum plate box in a home-made mould, pouring molten aluminum alloy into the cavity of the aluminum box, and cooling to finally obtain the composite cast ingot. The prepared aluminum coated magnesium alloy composite cast ingot can form a multilayer complicated metallurgical combined interface structure, so that high-quality ingots are provided to subsequent hot rolled aluminum-coated magnesium alloy composite plate band.