Q: Inconel 625 and Hastelloy C276 bolts seem to have similar Nickel content. Does this mean these fasteners will perform the same in a corrosive environment?

A: Inconel 625 and Hastelloy C276 bolts do offer similar corrosion resistance but Hastelloy C276 has a slight edge in many acidic environements, especially when fasteners are in hydrochloric (HCl) and sulfuric (H2SO4) acids. Though nickel is critical to corrosion resistance, molybdenium and chromium also play a role in this. Chromium provides resistance to oxidizing chemicals, whereas the high nickel and molybdenum contents supply resistance to non-oxidizing environments. Inconel 625 bolts have a higher chromium content than Hastelloy C276 bolts which provides it an edge in oxidizing environments, whereas Hastelloy C276 as a higher Molybdenum content which makes slightly it more resistant to acids than Inconel 625.