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, e.g. B2 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 B-3® alloy minimizes the problems associated with
fabrication of B2 alloy components. This is due to the reduced tendency to precipitate
deleterious intermetallic phases in B-3® alloy, thereby, affording it greater
ductility than B2 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 B-3® alloy 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. B-3® alloy is suitable for use in all applications previously
requiring the use of B2 alloy. Like B2 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 B-3® alloy over B2 alloy 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 B2 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 B-3® alloy (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.
|Element||Avg. Nominal % |
|Nickel||65.0 Min. |
| ( Ni + Mo makes up 94.0 - 98.0 ) |
|Cobalt||3.0 Max. |
|Tungsten||3.0 Max. |
|Silicon||0.10 Max. |
|Manganese||3.0 Max. |
|Carbon||0.01 Max. |
|Aluminium||0.50 Max. |
|Copper||0.20 Max. |