Brass is an alloy of copper and zinc. Varying the proportions of zinc and copper changes the properties of brass, allowing for both hard and soft varieties. Brass has been widely used since ancient times for decoration, utensils, and applications requiring low friction and corrosion resistance like locks and valves. The three types of brass crystal structures are alpha, beta, and alpha-beta brasses, which are distinguished by their zinc content and properties.

1. BRASS

2. INTRODUCTION
• Brass is an alloy of copper and zinc.
• The proportions of zinc and copper can be varied to create a range of brasses with
varying properties.
• It is used for decoration for its bright gold like appearance.
• It has also been widely used for all sorts of utensils due to many properties, such as
low melting point, workability (both with hand tools and with
modern turning and milling machines), durability, electrical and thermal
conductivity. It is still commonly used in applications where low friction and
corrosion resistance is required, such
as locks, hinges, gears, bearings, ammunition casings, zippers, plumbing, hose
couplings, valves, and electrical plugs and sockets.

3. HISTORY
• First produced by ancient metalworkers in the area now known as Syria or
eastern Turkey as early as 3000 B.C.
• By Roman period brass was being deliberately produced from metallic
copper and zinc minerals using the cementation process and variations on
this method continued until the mid-19th century.
• The process for combining metallic copper and zinc to make brass was
patented in England in 1781.

4. PROPERTIES
• Brass has higher malleability than bronze or zinc. The relatively low melting point of brass (900
to 940 °C, 1,650 to 1,720 °F, depending on composition) and its flow characteristics make it a
relatively easy material to cast.
• By varying the proportions of copper and zinc, the properties of the brass can be changed,
allowing hard and soft brasses.
• The density of brass is 8.4 to 8.73 g/cm3 (0.303 to 0.315 lb/cu in)
• Although copper and zinc have a large difference in electrical potential, the resulting brass alloy
does not experience internalized galvanic corrosion because of the absence of a corrosive
environment within the mixture. However, if brass is placed in contact with a more noble metal
such as silver or gold in such an environment, the brass will corrode galvanically; conversely, if
brass is in contact with a less-noble metal such as zinc or iron, the less noble metal will corrode
and the brass will be protected.

5. PROPERTIES(CONT…)
• As brass is not ferromagnetic, it can be separated from ferrous scrap by
passing the scrap near a powerful magnet. Brass scrap is collected and
transported to the foundry, where it is melted and recast into billets.
• Billets are heated and extruded into the desired form and size. The general
softness of brass means that it can often be machined without the use
of cutting fluid, though there are exceptions to this.
• Also, almost 90% of brass is recyclable.

6. PROPERTIES(CONT…)
• Brass will corrode in the presence of moisture, chlorides, acetates, ammonia,
and certain acids. This often happens when the copper reacts with sulfur to
form a brown and eventually black surface layer of copper sulfide which, if
regularly exposed to slightly acidic water such as urban rainwater, can then
oxidize in air to form a patina of green-blue copper sulfate. Depending on
how the sulfide/ sulfate layer was formed, this layer may protect the
underlying brass from further damage.

7. Types of Brass
The essential distinction between different types of brasses is
determined by their crystal structures.
Three different types of crystal structure can form:
• Alpha Brasses
• Alpha-Beta Brasses
• Beta Brasses

8. Alpha Brasses
• Alpha brasses contain less than 37% zinc melted into copper and are named for their
formation of a homogenous (alpha) crystal structure.
• Such brasses are softer and more ductile than their counterparts and, therefore, more
easily cold worked, welded, rolled, drawn, bent, or brazed.
• Alpha brass is used in common items such as:
• Pins
• Bolts
• Screws
• Ammunition Cartridge Cases

9. Beta Brasses
• Although much more rarely used than alpha or alpha-beta brasses, beta brasses
make up a third group of the alloy that contains greater than 45% zinc content.
• As such, they can only be hot worked or cast.
• Beta brass is used in common items such as:
• Taps
• Sprinkler heads
• Window fittings
• Door fittings

10. Alpha-Beta Brasses
• Alpha-beta brasses - also known as 'duplex brasses' or 'hot-working brasses' - contain between
37-45% zinc and are made-up of both the alpha grain structure and a beta grain structure.
• More common than alpha brass, alpha-beta brass is both harder and stronger and has a lower
cold ductility, than alpha brass.
• Alpha-beta brass is used in common items such as:
• Engraved nameplates
• Appliance trim
• Clock components
• Gear meters
• Builders hardware