Table 1-3.Surface Colors of Some Common Metals
One of the first of the strong structural aluminum
alloys developed is called Duralumin. With the devel-
opment of a variety of different wrought-aluminum
alloys, a numbering system was adopted. The digits
indicate the major alloying element and the cold-worked
or heat-treated condition of the metal. The alloy, origi-
nally called Duralumin, is now classified in the metal
working industries as 2017-T. The letter T indicates that
the metal is heat-treated.
This is a protective covering that consists of a thin
sheet of pure aluminum rolled onto the surface of an
aluminum alloy during manufacture. Zinc chromate is
a protective covering that can be applied to an aluminum
surface as needed. Zinc chromate is also used as a primer
on steel surfaces for a protective coating.
Monel is an alloy in which nickel is the major
element. It contains from 64% to 68% nickel, about 30%
copper, and small percentages of iron, manganese, and
cobalt. Monel is harder and stronger than either nickel
or copper and has high ductility. It resembles stainless
steel in appearance and has many of its qualities. The
strength, combined with a high resistance to corrosion,
make Monel an acceptable substitute for steel in systems
where corrosion resistance is the primary concern. Nuts,
bolts, screws, and various fittings are made of Monel.
This alloy can be worked cold and can be forged and
welded. If worked in the temperature range between
1200°F and 1600°F, it becomes hot short or brittle.
This is a special type of alloy developed for greater
strength and hardness than Monel. In strength, it is