Hastelloy B2 is a nickel-molybdenum alloy with significant resistance to reducing environments, such as hydrogen chloride gas and sulfuric, acetic and phosphoric acids. Hastelloy B2 provides resistance to pure sulfuric acid and a number of non-oxidizing acids. The alloy should not be used in oxidizing media or where oxidizing contaminants are available in reducing media. Premature failure may occur if alloy B2 is used where iron or copper is present in a system containing hydrochloric acid.
Industry users like the resistance to a wide range of organic acids and the resistance to chloride-induced stress-corrosion cracking.
Hastelloy B2 resists the formation of grain boundary carbide precipitates in the weld heat-affected zone, making it suitable for most chemical process applications in the as-welded condition. The heat-affected weld zones have reduced precipitation of carbides and other phases to ensure uniform corrosion resistance.
Alloy B2 also has excellent resistance to pitting and stress corrosion cracking.