Q: Looking at options to increase the tensile strength for a socket head cap screw. We
are currently using grade 8. Would Waspaloy be a good option?
A: If you are looking for a fastener with higher strength than Grade 8 Alloy Steel (150 KSI Tensile, 130 KSI Yield), and are only interested in strength (not corrosion resistance or high temperature stability etc.) you should consider 17-4 PH. This is a precipitation hardened stainless steel that lets you fine tune the strength depending on the heat treatment. 17-4PH bolts can deliver strength of 160-220ksi UTS.
Beyond this you are getting into some very special alloys that do more than just offer high strength, like Inconel 718, Waspaloy and MP35N. These materials relative to alloy steel are very expensive and typically used for high strength applications that have other requirements such as corrosion resistance or high temperature usage.