HASTELLOY  B-3

UNS Number N010675

Hastelloy B-3 is a nickel-molybdenum alloy with excellent resistance to pitting, corrosion, and stress-corrosion cracking plus, thermal stability superior to that of alloy B-2. In addition, this nickel steel alloy has great resistance to knife-line and heat–affected zone attack. Alloy B-3 also withstands sulfuric, acetic, formic and phosphoric acids, and other non-oxidizing media. Furthermore, this nickel alloy has excellent resistance to hydrochloric acid at all concentrations and temperatures. Hastelloy B-3’s distinguishing feature is its ability to maintain excellent ductility during transient exposures to intermediate temperatures. Such exposures are routinely experienced during heat treatments associated with fabrication.

Limiting Factors of Hastelloy B-3

Alloy B-3 has poor corrosion resistance to oxidizing environments, therefore, it is not recommended for use in oxidizing media or in the presence of ferric or cupric salts because they may cause rapid premature corrosion failure. These salts may develop when hydrochloric acid comes in contact with iron and copper. Therefore, if this nickel steel alloy is used in conjunction with iron or copper piping in a system containing hydrochloric acid, the presence of these salts could cause the alloy to fail prematurely.

In what forms is Hastelloy B-3?

Sheet

Plate

Bar

Pipe (welded & seamless)

Fittings (i.e. flanges, slip-ons, blinds, weld-necks, lapjoints, long welding necks, socket welds, elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples)

What are the characteristics of Hastelloy B-3?

Maintains excellent ductility during transient exposures to intermediate temperatures

Excellent resistance to pitting, corrosion and stress-corrosion cracking

Excellent resistance to knife-line and heat-affected zone attack

Excellent resistance to acetic, formic and phosphoric acids and other non-oxidizing media

Resistance to hydrochloric acid at all concentrations and temperatures

Thermal stability superior to alloy B-2

Chemical Composition(%) 

In what applications is Hastelloy B-3 used?

Chemical processes

Vacuum furnaces

Mechanical components in reducing environments

Fabrication with Hastelloy B-3

Problems associated with fabrication of alloy B-2 components should be minimized with alloy B-3 due to its improved thermal stability. A low carbon content permits alloy B-3 to be used in the as-welded condition. Hastelloy B-3 has good overall forming and welding characteristics. This alloy can be forged or otherwise hot-worked, providing that it is held at 2250° F for a sufficient amount of time 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. It 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. All common welding techniques may be used with alloy B-3, however, oxyacetylene and submerged arc welding processes are not recommended when the fabricated item is to be used in corrosive service.

ASTM Specifications