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Brass
What Is
Brass? Composition and Properties
Brass Composition, Properties,
and Comparison With Bronze
by Anne Marie
Helmenstine, Ph.D.
Brass is an alloy made
primarily of copper and zinc.
The proportions of the
copper and zinc are varied to yield many different kinds of brass.
Basic modern brass is 67%
copper and 33% zinc. However, the amount of copper may range from 55% to 95% by
weight, with the amount of zinc varying from 5% to 40%.
Lead is
commonly added to brass at a concentration of around 2%. The lead addition
improves the machinability of brass.
However, significant lead
leaching often occurs, even in brass that contains a relatively low overall
concentration of lead.
Uses of brass include
musical instruments, firearm cartridge casing, radiators, architectural trim,
pipes and tubing, screws, and decorative items.
Brass Properties
· Brass
often has a bright gold appearance, however, it can also be
reddish-gold or silvery-white. A higher percentage of copper yields a rosy
tone, while more zinc makes the alloy appear silver.
· Brass
has higher malleability than either bronze or zinc.
· Brass
has desirable acoustic properties appropriate for use in musical instruments.
· The
metal exhibits low friction.
· Brass
is a soft metal that may be used in cases when a low chance of sparking is
necessary.
· The
alloy has a relatively low melting point.
· It's a
good conductor of heat.
· Brass
resists corrosion,
including galvanic corrosion from saltwater.
· Brass
is easy to cast.
· Brass
is not ferromagnetic.
Among other things, this makes it easier to separate from other metals for
recycling.
Brass vs. Bronze
Brass and bronze may
appear similar, yet they are two distinct alloys. Here's a comparison between
them:
Identifying Brass Composition
by Name
Brass
|
Bronze
|
|
Composition
|
Alloy
of copper and zinc. Commonly contains lead. May include iron, manganese,
aluminum, silicon, or other elements.
|
Alloy
of copper, usually with tin, but sometimes other elements, including
manganese, phosphorus, silicon, and aluminum.
|
Color
|
Golden
yellow, reddish gold, or silver.
|
Usually
reddish brown and not as bright as brass.
|
Properties
|
More
malleable than copper or zinc. Not as hard as steel. Corrosion resistant.
Exposure to ammonia may produce stress cracking. Low melting point.
|
Better
conductor of heat and electricity than many steels. Corrosion resistant.
Brittle, hard, resists fatigue. Usually a slightly higher melting point than
brass.
|
Uses
|
Musical
instruments, plumbing, decoration, low-friction applications (e.g., valves,
locks), tools and fittings used around explosives.
|
Bronze
sculpture, bells and cymbals, mirrors and reflectors, ship fittings,
submerged parts, springs, electrical connectors.
|
History
|
Brass
dates back to around 500 B.C.E.
|
Bronze
is an older alloy, dating back to about 3500 B.C.E.
|
Common names for brass alloys may
be misleading, so the Unified Numbering System for metals and alloys is the
best way to know the composition of the metal and predict its applications.
The letter C indicates
brass is a copper alloy. The letter is followed by five digits.
Wrought brasses — which
are suitable for mechanical forming — begin with 1 through 7.
Cast brasses, which may
be formed from molded molten metal, are indicated using an 8 or 9.
Anne Marie Helmenstine,
Ph.D.
Introduction
Ph.D. in biomedical sciences
from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.
Science educator with
experience teaching chemistry, biology, astronomy, and physics at the high school,
college, and graduate levels.
ThoughtCo and About Education
chemistry expert since 2001.
Widely-published graphic
artist, responsible for printable periodic tables and other illustrations used
in science.
Experience
Anne Helmenstine,
Ph.D. has covered chemistry for ThoughtCo and About Education since 2001,
and other sciences since 2013. She taught chemistry, biology, astronomy, and
physics at the high school, college, and graduate levels. She has worked
as a research scientist and also abstracting and indexing diverse scientific
literature for the Department of Energy.
In addition to her work as a
science writer, Dr. Helmenstine currently serves as a scientific consultant,
specializing in problems requiring an interdisciplinary
approach. Previously, she worked as a research scientist and college
professor.
Education
Dr. Helmenstine holds a Ph.D.
in biomedical sciences from the University of Tennessee at Knoxville and a
B.A. in physics and mathematics with a minor in chemistry from Hastings
College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive
chemical detection and medical diagnostic tests.
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