Manufacturing method of aluminum magnesium alloy

The invention relates to a manufacturing method of plates and particularly relates to a manufacturing method of an aluminum magnesium alloy thick plate, which can be used for solving the problems that a process for processing a plate made of aluminum alloy 5083 which is in the H321 state and is 12.5-75mm in thickness, and the aluminum alloy 5083 being in the H321 state and being 12.5-75mm in thickness, which is prepared by the existing casting method, is poor in strength and percentage elongation. The method comprises the steps of firstly, melting; secondly, casting; thirdly, evening fire; fourthly, rolling and fifthly, annealing. According to the method disclosed by the invention, the blank of the manufacturing method of an alloy thick plate 5083H321 being 12.5-75mm in thickness is filled; and according to the method, a reasonable technological process is selected, so that the yield strength of the plate is 275-293MPa, the tensile strength of the plate is 350-365MPa, and the percentage elongation of the plate is 10.8-11.9%. The aluminum magnesium alloy thick plate manufactured by the method can be used for the industrial fields of armored vehicles, ships, automobile industries, and canning.