The principle of selecting aluminum alloy for ships has the following four points:
One is the high specific strength and specific modulus. The structural strength and size of the ship are closely related to the yield strength and elastic modulus of the material. Since the elastic modulus and density of the aluminum alloy are generally the same, the addition of alloying elements has little effect, so the yield strength is reduced within a certain range. The ship structure is powerful. High-strength aluminum alloys are often difficult to have both excellent corrosion resistance and weldability. Therefore, marine aluminum alloys are generally medium strength, corrosion resistant weldable alloys.
The second is excellent welding performance. At present, the main method used in the ship is the automatic argon arc welding method. Good weldability means that the tendency of the aluminum alloy to form cracks during welding is small, that is, the aluminum alloy has good welding crack resistance. The lost weldability cannot be restored by reheating under shipbuilding conditions.
The third is excellent corrosion resistance. The ship's structure is used in many harsh seawater media and in the marine environment. Therefore, corrosion resistance is one of the main signs of marine alloys.
Fourth, aluminum alloy has good cold and hot forming properties. Because the ship is manufactured by cold processing and hot processing, the marine aluminum alloy must be easy to process, no crack defects, and can still meet the strength and corrosion requirements after processing.
The selection of marine aluminum alloy is more stringent. At present, more aluminum alloy products such as 5083, 5086, 5454, 5754 and 6061 are used. In practical applications, the advantages of marine aluminum alloys are very obvious. The first is the small specific gravity, which can reduce the weight of the ship, save energy and increase the load; secondly, it is good in corrosion resistance, reducing the cost of oiling and extending the service life; thirdly, it has good welding and processing performance, which is good for post-processing; The waste is easy to recycle and can be recycled. At the same time, it does not burn and is safe to fire.