Difference between Incoloy 825 and 925 bolts

Q: What is the difference between Incoloy 825 and 925 bolts?

A: Bolts made from Incoloy 925 are precipitation hardened version of Incoloy 825 bolts. What this means is it is put through a heat treatment process which hardens the alloy at the atomic level. Basically Incoloy 925 bolts offers similar corrosion resistance but are much stronger. Comparing tensile strength, Incoloy 925 has a tensile strength of 167 ksi where that of Incoloy 825 is only 100 ksi.