Machining process of marine aluminum alloy frame keel

The invention discloses a machining process of a marine aluminum alloy frame keel. The machining process is characterized in that the aluminum alloy frame keel is formed by a 5383 aluminum alloy through extrusion; the machining process specifically includes the following steps that firstly, a 5383 aluminum alloy cast ingot is prepared, wherein a 5383 aluminum alloy raw material is prepared from, by weight, smaller than or equal to 0.1% of Si, smaller than or equal to 0.2% of Fe, smaller than or equal to 0.1% of Cu, 0.72%-0.85% of Mn, 4.20%-4.65% of Mg, smaller than or equal to 0.15% of Zn, smaller than or equal to 0.05% of Ti, smaller than or equal to 0.05% of each single impurity and the balance Al, the total weight percentage of the impurities is smaller than or equal to 0.15%, the prepared 5383 aluminum alloy raw material is added in a smelting furnace to be molten into aluminum liquid, and then the aluminum liquid is cast into the aluminum alloy cast ingot; secondly, homogenizing is conducted; thirdly, ex