Q: I have an application in which I require a 1/2in-13 Hex bolt that will be in an inert gaseous environment at 500C. The bolt will be fastened to a Titanium Grade 5 nut. What material bolt would work best?
A: I would suggest either Inconel 625 or Inconel 718 for your application. It just depends on how much strength you need. The Inconel 718 is very strong with a min Tensile of 180KSI while Inconel 625 has a min or 120KSI. As long as you stay below 700C you should be OK with the Inconel 718 and the Inconel 625 can go to almost 1000C.