About Monel
What exactly is Monel you might be asking right about now. You
have heard that WWII dog tags were made of it, but don't quite know what it
is.
Monel or Alloy 4000, is a nickel alloy containing 65-70 percent nickel,
20-29 percent copper, and small amounts of iron, manganese, silicon and
carbon discovered due to the efforts of Robert Crooks Stanley, who worked
for the International Nickel Company (INCO) in 1901. The new alloy which
was named in honor of the president of the company, Ambrose Monell, was
said to be:
- Stronger than steel
- Malleable
- Resistant to corrosion
- Low coefficient of thermal expansion
- Highly resistant to alkalis
- Improved sanitation (??)
- Fairly inexpensive
- Can be welded, brazed and soldered
In the 1920s and 30s, Monel was available in both hot-rolled and
cold-rolled sheets typical finishes included brightly polished,
"hand-forged" black, and two-toned in outdoor applications, Monel develops
a patina ranging from light gray-green to medium brown.
Currently, Monel is a trademark of Special Metals
Corporation
Typical Uses
- Popular between 1909 and the mid 1950s
- Available in sheet form for architectural applications
- Installed as a sheet roofing membrane in 1908
- In the late 1920s, Monel was began to be used for grocery coolers,
countertops, sinks, laundry and food preparation appliances, roofing and
flashing
- Other uses for sheet and plate Monel were ductwork, flashing, gutters
and downspouts, mail chutes, laundry chutes, elevator fittings, lighting
fixtures, and skylights
- Monel castings were also popular and included grilles, rosettes,
plaques, handrail fittings, molding, pilasters, mullions, and door jambs
- Monel forgings were used for hardware
- Monel bar and rod stock were used for window screens, gates, public
directory boards, railings, and divider strips in terrazzo floors
- Other common applications for Monel included tie wire for securing
lath in plaster walls and suspended ceilings, fasteners for tile roofs
and anchors for stone cladding
- Monel began to be displaced by stainless steel in the 1950s, as
stainless steel could produce the same forms at a lower cost (due to use
of less nickel)
- A modified, less expensive use of Monel included laminating a thin
sheet of Monel to an inexpensive backing material; two examples include
Monel-clad steel and Monel-laminated plywood
- Monel is still manufactured by INCO, primarily in the form of sheet
goods; cast and rolled forms are also available, but are extremely
expensive
Natural or Inherent Problems
- Surface discoloration: Can occur
from exposure to atmospheric condition
- Pitting: Can occur if exposed to
stagnant salt water.
- Galvanic corrosion: Metals, such
as aluminum, zinc and iron will corrode when in contact with Monel and
exposed to severe weather conditions. Therefore, use of these metals as
fasteners for Monel should be avoided.
- Stress corrosion cracking:
Exposure to aerated hydrofluoric acid in moist conditions can cause this
to occur.
- Corrosion resistance:
- Nitric oxides and sulfur dioxides, combined with water, are very
corrosive to Monel.
- Nitric and nitrous acids can be very corrosive to Monel at room
temperature
- Hypochlorites are severely corrosive to Monel if not diluted
- Acid and alkaline oxidizing salts, ferric chloride, ferric sulfate,
cupric chloride, stannic chloride, mercuric chloride and silver nitrate
are all corrosive to Monel.
- Resistance to sulfurous acid varies depending on climatic
conditions
- Organic acids (acetic and fatty acids) have little to no effect on
Monel
More dog tag information:
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