Q: I have a high strength application that requires resistance to damp salt air and occasional sea splash, I’m using Monel 400 but it’s not holding up the the 75ksi of yield I need. Lots of broken bolts? Is is corrosion or strength? Thoughts?
A: Your issue isn’t the corrosion. Monel bolts offer superior salt water protection even in deep sea environments. This is a strength issue. Monel 400 only offers about 45ksi of yield so 75ksi would definitely cause breakage. You could try Monel K500 which has a yield up to 110ksi and is excellent in salt water, but In terms of both corrosion and strength it would probably be overkill. The most economic bolt for your application would be Duplex 2507. Duplex bolts are known for their high yield strength twice that of austenitic stainless steels. In addition, Duplex 2507 bolts contain nickel, molybdenum and chromium providing good resistance to chlorides and salt water environments.