Ships have special requirements for the strength, corrosion resistance and weldability of aluminum alloys, so when choosing marine aluminum sheet, Al-Mg alloy, Al-Mg-Si or Al-Zn-Mg alloy is often used.
The strength of Al-Zn-Mg and Al-Mg-Si decreases significantly after welding. Among them, the corrosion resistance of aluminum-zinc-magnesium alloys after welding is relatively poor, therefore they are subject to certain restrictions as a welding material. But Al-Mg aluminum alloy don’t have such shortcomings.
5086 Aluminum belongs to 5xxx Al-Mg alloy. Its Mg content is generally does not exceed 7%. With the increase of the magnesium content, the alloy strength will increase, while the plasticity will decrease. 5086 aluminum plate is usually used in annealed, cold work hardened or semi-cold work hardened state.
Due to the effect of magnesium, the density of 5086 aluminum sheet is larger than other aluminum plates, and it has very good corrosion resistance. It is also a well known rust-proof aluminum sheet.
According to the content of magnesium, the anti-rust aluminum plate can be divided into three categories: low magnesium content, medium magnesium content and high magnesium content. The aluminum sheet with low magnesium content is non-heat treatment strengthening. It also has relatively low strength, good weldability and good welding performance.
The aluminum plate with medium magnesium content is generally used for pipes and containers with high plasticity and medium corrosion resistance, while the anti-rust aluminum plate with high magnesium content is generally used for ordinary welded pipes, liquid containers and other parts.
5086 aluminum plate is of low magnesium content. Its application field has relatively high requirements for product performance. Therefore, its processing fee is higher than other 5xxx aluminum. Its tensile strength σb (MPa): ≥240, conditional yield strength σ0.2 (MPa): ≥95.
From 1966 to 1971, the United States built the first batch of 14 "Acivil"-class high-speed gunboats. The main deck and bottom of the ship were made of 12.7mm thick 5086-H32 aluminum alloy. The entire boat shared 71 tons of aluminum and all were welded by argon arc welding. It perfectly prevent rivets from loosening, water seepage and contact corrosion.
Original Source:https://www.marinealu.com/a/5086-rust-proof-aluminum.html
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