Q: I’m looking for a high temperature, strong fastener. I noticed that Hastelloy C276 bolts can be used to 1500F where A286 screws can only be used to 1300F. Does that make Hastelloy a better choice?
A: Typically not. Hastelloy screws are most often used for high temperature corrosion. For example hot sulfuric acid. In terms of high temperature strength they are not a good choice. They only offer 100 ksi of tensile strength compared to A286 which offers 120-160 ksi. A286 bolts are known for their high temperature strength and would be a much better choice in your situation. A286 is an age hardened alloy which offers strength, as well as oxidation and creep resistance at high temperatures.