Q: I’m dealing with a brackish marine environment where fresh and salt water combine. I need a strong bolt around 120ksi of tensile strength and have been using Titanium Grade 5, but they are quite expensive. I was wondering if there is a more economic alternative that can handle this environment.
A: For your situation I would suggest you try a Super Duplex bolt. Super Duplex 2507 offers twice that of annealed austenitic stainless steels with about 125 ksi of tensile strength so they should be able to handle the strength of your application. In regards to the corrosion situation, a Super Duplex screw will be a good option since they do well in brackish / low salt content waters like you are dealing with.