2024 marine grade aluminum alloy
Durability of ductile aluminum is relatively low, mainly due to Cu. Someone had a very serious pitting corrosion after 16 days of testing coupons on a hard aluminum hull. The Soviet Union scholars D16AT alloy to the aluminum layer after the sample test 45 days, the loss of strength in Table 1, yield strength service Rp0.2 become significant.
As can be seen from the data in the table, the D16AT alloy plate without clad aluminum layer is severely corroded in seawater, however, the clad aluminum layer is much less corroded. Because the clad aluminum layer not only plays the role of protecting the alloy, but also plays an electrochemical protective role. For the 2XXX alloy, the 1XXX alloy clad aluminum layer is anodic, which ensures that the 2XXX alloy is protected from corrosion damage. Sometimes, even if the local aluminum layer is peeled off or suffered mechanical damage, it will not cause alloy corrosion because the clad aluminum layer in other parts still functions as a chemi-protection. This means that aluminum and aluminum superplastic corrosion resistance of the inherent deficiencies can be improved by conditioning the day after tomorrow.
5754 marine grade aluminum alloy
The most resistant to seawater corrosion in aluminum alloy is 5XXX series of alloys, the corrosion rate in seawater is very slow, and their corrosion resistance and magnesium content. Alloys with Mg ≤ 5% have good corrosion resistance; alloys containing> 5% Mg tend to have intergranular corrosion and stress corrosion cracking tendency if they are not heat treated (annealed).
5754 marine grade aluminum alloy
, 2024 marine grade aluminum alloy
and shipbuilding steel immersed in 3% NaCl solution 9 months after the change in mechanical properties in Table 2, the corrosion resistance of aluminum-magnesium alloy than 2024 marine grade aluminum alloy
and shipbuilding steel It is much stronger, not only the mass loss is small, but also the loss of mechanical properties is small, which shows that there are obvious superiorities in making the hull of aluminum-magnesium alloy.
The study by American scholar CW Civio pointed out that the 5754 marine grade aluminum alloy
(containing 4.0% -4.9% Mg, one American alloy, stereotyped in the late 1930s) and 5086 alloy (containing 3.5% -4.5% Mg, also one American alloy, stereotyped in the early 40s of the last century, then grade 86S) and some other alloys were immersed in sea water without any protective measures. The maximum depth of corrosion pits in 5086-H34 alloy samples after 6 years was 0.86 mm, but no A large loss of strength; another test was to partially and totally dip unsplit and welded 5086 and 5083 marine aluminum sheets into Tonoconian water in Florida for 5 and 7 years. After 5 years, the strength loss of 5086 and 8083 samples of fully immersed unprotected welds was negligible. There was almost no corrosion pits found, and the maximum depth of corrosion pits was only 0.38 mm. In partially impregnated specimens, the 5086 and the 5083 alloy, which are not welded at 3.2 mm thick, have negligible strength loss regardless of immersion conditions, demonstrating that the 5086 and 5083 alloys retain intrinsic resistance to seawater stress corrosion.