Q:
I need a salt water corrosion resistant screw that will work well to fasten an aluminum housing for deep sea equipment. I am concerned about galvanic corrosion. What material should I consider?
A:
Since you are using fasteners in an ocean environment and in contact with aluminum you have two concerns: first salt water corrosion and second is galvanic corrosion. To solve both issues, I’d suggest titanium screws. Titanium is excellent in preventing seawater corrosion, in both moving and stagnant water, even a mile deep. Titanium screws will also solve the second issue of galvanic corrosion prevention as they have a low galvanic potential with Aluminum and are the more noble metal, which is what you want your fasteners to be as the bulk housing will generally distribute the galvanic charge over a large mass. Another fastener to consider is Monel. This chart may be helpful to demonstrate this. https://www.extreme-bolt.com/a