Hastelloy B-2 flanges

Alloy B2 is a solid solution strengthened, nickel-molybdenum alloy, typically used in extreme reducing conditions. B2 has significantly lower carbon, silicon and iron compared to its’ predecessor, Alloy B (UNS N10001), making the alloy less susceptible to decreased corrosion resistance in the weld zone, in the as-welded condition. Controlling other alloying elements such as iron and chromium solved other issues concerning fabricability. Stringent chemistry control along with years of development has resulted in the alloy used today, both in Alloy B2 and Alloy B-3 Today, Alloy B2 with restricted chemistry can be used in the welded condition and is less susceptible to SCC under many conditions. As always, care must taken in selecting the right alloy for the desired application.
Alloy B2 should not be used at temperatures between 1000°F and 1600°F as the alloy forms secondary phases that could decrease the ductility of the material.