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!