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Hi Frederik, You're on the right path with Type III hard anodizing for your submersible components. The 25-50 μm thickness is generally good for balancing wear resistance and minimizing cracking risk under stress. However, considering your concerns about high-cycle fatigue, you might explore a thinner layer or use a post-anodizing sealing process like nickel acetate or hot water sealing to enhance corrosion resistance. Also, consider duplex coatings or other protective measures suited for marine environments. Regular stress tests and inspections will also be crucial to detect any early signs of failure. Best of luck with your project! Cheers!

[FrederikH.]

Hi all, I’m currently working on a marine application focusing on submersible components that require 6061-T6 aluminium. The part must undergo anodizing to ensure its wear and corrosion resistance when exposed to seawater.
At the moment I’m considering type III hard anodizing. However, I have some concerns regarding the possibility of fatigue cracks in the anodized layer due to the part experiencing tensile stresses up to 40,000 psi and compressive stresses up to 35,000 psi and high cycle fatigue (with stress cycles expected to exceed 10^5 cycles). I’m afraid that further cracks could not only lead to corrosion but also cause the part to crack.
Considering the need for both corrosion resistance and wear resistance, I’m determining the most suitable type and thickness for the anodized layer. Initial recommendations suggest a thickness of 25-50 μm for type III anodizing to provide a good balance between wear resistance and the ability to withstand mechanical stresses without significant risk of cracking.

However, I’m interested in hearing if there are alternative recommendations or insights based on practical experiences or additional research. Thank you!

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[Attila Szucs]

Hi Frederik,

You’re on the right path with Type III hard anodizing for your submersible components. The 25-50 μm thickness is generally good for balancing wear resistance and minimizing cracking risk under stress.

However, considering your concerns about high-cycle fatigue, you might explore a thinner layer or use a post-anodizing sealing process like nickel acetate or hot water sealing to enhance corrosion resistance. Also, consider duplex coatings or other protective measures suited for marine environments.

Regular stress tests and inspections will also be crucial to detect any early signs of failure.

Best of luck with your project!

Cheers!

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