What Is Hastelloy B3?

Introduction to Hastelloy B3

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 B3’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.

Designated as UNS N10675 or W.Nr. 2.4600, Hastelloy B3 (also known as “Alloy B3”), is a nickel-molybdenum alloy with the addition of chromium, iron and other elements. It has excellent resistance to hydrochloric acid at all concentrations and temperatures. It also has good performance in sulfuric, acetic, formic and phosphoric acids, and other non-oxidizing media. Alloy B3 has excellent resistance to pitting corrosion, stress-corrosion cracking and to knife-line and heat-affected zone attack. Compared to Hastelloy B2, Hastelloy B3 has more superior thermal stability. It’s widely used in chemical processes, vacuum furnaces, and piping components in reducing environments.

Properties of Hastelloy B3

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 non-oxidizing media. B-3 alloy has a special chemistry designed to achieve a level of thermal stability greatly superior to that of it predecessors.

Hastelloy B3 has excellent resistance to pitting corrosion, to stress-corrosion cracking and to knife-line and heat-affected zone attack. The improved thermal stability of 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. B-3 alloy has good overall forming and welding characteristics. It may be forged or otherwise hot-worked, providing that it is held 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 recommended when the fabricated item is to be used in corrosive service. Special precautions should be taken to avoid excessive heat input. All wrought forms of Hastelloy B3 are furnished in the solution heat-treated condition unless otherwise specified. B-3 alloy is solution heat-treated at 1950°F (1065°C) and rapid quenched, except for bright annealed sheet or coil products which are heat-treated at 2100°F (1150°C) and cooled in hydrogen. B-3 alloy is available in form of plate, sheet, strip, billet, bar, wire, pipe and tubing. Hastelloy B3 is suitable for use in all applications previously requiring the use of B-2 alloy. Like B-2 alloy, B-3 is not recommended for use in the presence of ferric or cupric salts as these salts may cause rapid corrosion failure. Ferric or cupric salts may develop when hydrochloric acid comes into contact with iron or copper.

The single greatest advantage for Hastelloy B3 over Hastelloy B2 accrues from its ability to maintain excellent ductility during transient exposures to intermediate temperatures. Such exposures are routinely experienced during heat treatments associated with fabrication. While very short exposures at temperatures such as 1290°F (700°C) can severely embrittle B-2 alloy at temperature, B-3 alloy exhibits a marked resistance to such embrittlement for up to several hours. This provides far greater facility for the alloy to be fabricated into complex components such as formed heads. ASME has published Code Case 2140 for solution annealed Hastelloy B3 (UNS N10675). The alloy is also covered by ASTM specifications B-333 (plate, sheet and strip), B-335 (bar), B-366 (welded fittings), B564 (forgings), B619 (welded pipe), B622 (seamless pipe and tube) and B626 (welded tube). B-3 is a registered trademark of Haynes International Inc.

Chemical Composition Analysis of Hastelloy B3

Hastelloy B3 is high-performance nickel alloys known for their excellent corrosion resistance in various aggressive media. Hastelloy B3 contain nickel, molybdenum, chromium, tungsten, iron, manganese and copper as primary alloying elements.  Hastelloy B3 typically contains higher Niobium levels, improving its corrosion resistance properties in certain oxidizing environments. Hastelloy B3 has been primarily used for their resistance to corrosion in nonoxidizing environments such as HCl.But it is is not recommended for use in the presence of ferric or cupric salts because these salts can cause premature failure.

Hastelloy B3 produced by NiWire is well suited for equipment handling hydrochloric acid in all concentrations and temperatures. Resistant to hydrogen chloride gas and sulfuric, acetic, and phosphoric acids. Principal high-temperature uses are those in which a low coefficient of thermal expansion is required. The following table shows the chemical composition of HASTELLOY B3:

Applications of Hastelloy B3

Oil & Gas Industrires

Chemical Industries

Construction Industries

In Offshore Pipelines, Pipe Works

Petrochemical Industry

Shipbuilding Industries

Hydraulic Applications

Piping Systems