HASTELLOY B-3 alloy is an additional member of the nickel-molybdenum family of alloys with excellent resistance to hydrochloric acid at all concentrations and temperatures. It also withstands sulfuric, acetic, formic and phosphoric acids, and other nonoxidizing media. B-3 alloy has a special chemistry designed to achieve a level of thermal stability greatly superior to that of its predecessors, e.g. HASTELLOY B-2 alloy. B-3 alloy has excellent resistance to pitting corrosion, to stress-corrosion cracking and to knife-line and heat-affected zone attack.
The improved thermal stability of HASTELLOY B-3 alloy minimizes the problems associated with fabrication of B-2 alloy components. This is due to the reduced tendency to precipitate deleterious intermetallic phases in B-3 alloy, thereby, affording it greater ductility than B-2 alloy during and following various thermal cycling conditions. HASTELLOY B-3 alloy has good overall forming and welding characteristics. It may be forged or otherwise hotworked, providing that it isheld at 2250°F (1230°C) for a time sufficient to bring the entire piece to temperature. Since it is a low carbon alloy, the use of lower hot finishing temperatures may be necessary to achieve grain size control. B-3 alloy may also be formed by cold working. Although it does work-harden somewhat rapidly, B-3 alloy components can be made using all common cold forming techniques. Limited tests in boiling 20 percent hydrochloric acid indicate that the uniform corrosion resistance of B-3 alloy is not affected by cold reductions up to 50 percent as compared to that of the alloy in the solution heat-treated condition. B-3 alloy can be welded by all common welding techniques, although oxyacetylene and submerged arc welding processes are not recommended when the fabricated item is to be used in corrosive service. Special precautions should be taken to avoid excessive heat input.
