Copper and copper alloys constitute one of the mayor groups
of commercial metals. They are widely used because of their excellent
electrical and thermal conductivities, outstanding resistance to corrosion,
ease of fabrication, and good strength and fatigue resistance...
Copper and copper alloys constitute one of the mayor groups of commercial metals.
They are widely used because of their excellent electrical and thermal
conductivities, outstanding resistance to corrosion, ease of fabrication,
and good strength and fatigue resistance. They are generally nonmagnetic.
They can be readily soldered and brazed, and many coppers and copper alloys
can be welded by various gas, arc, and resistance methods.
For decorative parts, standard alloys having specific colors are readily
available. Copper alloys can be polished and buffed to almost any desired
texture and luster. They can be plated, coated with organic substances,
or chemically colored to further extend to variety of available finishes.
The most common way to catalog copper and copper alloys is to divide
them into six families: coppers, dilute-copper (or high-copper) alloys,
brasses, bronzes, copper-nickels, and nickel silvers. The first family,
the coppers, is essentially commercially pure copper, which ordinarily
is soft and ductile and contains less than about 0,7% total impurities.
The dilute-copper alloys contain small amounts of various alloying elements,
such as beryllium, cadmium, chromium, or iron each having less than 8 at.%
solid solubility; these elements modify one or more of the basic properties
of copper.
A general classification for wrought and cast copper alloys is given in the
following table.
Table of UNS Designations for Copper and Copper alloys
Generic name
|
UNS numbers
|
Composition
|
Wrought alloys
|
Coppers
|
C10100-C15760
|
>99%Cu
|
High-copper alloys
|
C16200-C19600
|
>96%Cu
|
Brasses
|
C20500-C28580
|
Cu-Zn
|
Leaded brasses
|
C31200-C38590
|
Cu-Zn-Pb
|
Tin brasses
|
C40400-C49080
|
Cu-Zn-Sn-Pb
|
Phosphor bronzes
|
C50100-C52400
|
Cu-Sn-P
|
Leaded phosphor bronzes
|
C53200-C54800
|
Cu-Sn-Pb-P
|
Copper-phosphorus and copper-silver phosphorus alloys
|
C55180-C55284
|
Cu-P-Ag
|
Aluminum bronzes
|
C60600-C64400
|
Cu-Al-Ni-Fe-Si-Sn
|
Silicon bronzes
|
C64700-C66100
|
Cu-Si-Sn
|
Other copper-zinc alloys
|
C66400-C69900
|
|
Copper-nickels
|
C70000-C79900
|
Cu-Ni-Fe
|
Nickel silvers
|
C73200-C79900
|
Cu-Ni-Zn
|
Cast alloys
|
Coppers
|
C80100-C81100
|
>99%Cu
|
High-copper alloys
|
C81300-C82800
|
>96%Cu
|
Red and leaded red brasses
|
C83300-C85800
|
Cu-Zn-Sn-Pb(75-89%Cu)
|
Yellow and leaded yellow brasses
|
C85200-C85800
|
Cu-Zn-Sn-Pb(57-74%Cu)
|
Manganese bronzes and leaded manganese bronzes
|
C86100-C86800
|
Cu-Zn-Mn-Fe-Pb
|
Silicon bronzes, silicon brasses
|
C87300-C87900
|
Cu-Zn-Si
|
Tin bronzes and leaded tin bronzes
|
C90200-C94500
|
Cu-Sn-Zn-Pb
|
Nickel-tin bronzes
|
C94700-C94900
|
Cu-Ni-Sn-Zn-Pb
|
Aluminum bronzes
|
C95200-C95810
|
Cu-Al-Fe-Ni
|
Copper-nickels
|
C96200-C96800
|
Cu-Ni-Fe
|
Nickel silvers
|
C97300-C97800
|
Cu-Ni-Zn-Pb-Sn
|
Leaded coppers
|
C98200-C98800
|
Cu-Pb
|
Miscellaneous alloys
|
C99300-C99750
|
|
|
Commercially pure copper is represented by UNS numbers C10100 to
C13000. The various coppers within this group have different degrees
of purity and therefore different characteristics.
Alloy C15100 (copper–zirconium), alloy C15500
(copper–silver–magnesium–phosphorus), alloy C19400
(copper–iron–phosphorus-zinc), and alloy C19500
(copper–iron–cobalt–tin–phosphorus)
are popular for these applications because they have good
conductivity, good strength, and good softening resistance.
Age hardening produces very high strenghts but is limited to those
few copper alloys in which the solubility of the alloying element
decreases sharply with decreasing temperature. The beryllium-coppers
can be precipitation hardened to the highest strength levels
attainable in copper-base alloys. There are two commercially
significant alloy families employing two ranges of beryllium
with additions of cobalt or nickel.
Other age-hardenable alloys include C15000, C15100 (zirconium-copper),
C18200, C18400, and C18500 (chromium-coppers), C19000 and C19100
(copper-nickel-phosphorus alloys). Some age-hardening alloys have
different desirable characteristics, such as high strength combined
with better electrical conductivity than the beryllium-coppers.
Certain aluminum bronzes, most notably those containing more
than about 9 % Al, can be hardened by quenching from above a
critical temperature. The hardening process is martensitic-type
process, similar to the martensitic hardening that occurs when
iron-carbon alloys are quenched.
Mechanical properties of aluminum bronzes can be varied somewhat
by temper annealing after quenching or by using an interrupted
quench instead of a standard quench. Aluminum bronzes alloyed
with nickel or zinc use reversible martensitic transformations
to provide shape memory effects.
Lead, tellurium, and selenium are added to copper and copper
alloys to improve machinability. These elements, along with bismuth,
make hot rolling and hot forming nearly impossible and severely
limit the useful range of cold working. The high-zinc brasses
avoid these limitations, however, because they become fully b
phase at high temperature. The b phase can dissolve lead, thus
avoiding a liquid grain-boundary phase at hot forging or extrusion
temperatures.