Brasses: Alpha Phase, Beta Phase, Gamma Phase, Red Brass, Properties, Yellow Brass or Muntz Metal, Cartridge Brass, Admiralty Brass, Naval Brass, Manganese Brass, Iron Brass or Delta Metal, Gilding Brass, Free Cutting Brass, Lead Brass

Brasses

Brasses are widely used alloy of copper (main
constituent) and zinc. They also contain small amounts of lead or tin or aluminium.
The most commonly used copper-zinc alloy is
brass.
There are various types of brasses, depending upon the proportion of
copper and zinc.
The fundamental a
binary alloy comprises 50% copper and 50% zinc. By adding small quantities of
other elements, properties of brass may be greatly changed. For example
addition of lead
  (1 to 2%) improves the
machining quality of brass. It has a greater-strength than that of
copper, but has a lower thermal and
electrical
conductivity. Brasses
alloys are very resistant to
atmospheric corrosion and can be easily soldered. They can be easily fabricated by processes like
spinning and can also be electroplated with metals like nickel and chromium.
Some of common
phases of brass are discussed as under.

Alpha Phase

If the copper crystal structure
is face centered cubic (FCC), there will be up to 36% of zinc. This solid
solution is known as alpha brass. It has good mechanical properties, good
corrosion resistance but it possesses lower electrical conductivity than
copper.

Beta Phase

If the amount of zinc increases
beyond 36%, beta brass will appear in the microstructure of the slowly cooled
brass. This has body centered cubic structure (BCC). This phase is hard but
quite tough at room temperature.

Gamma Phase

When zinc content is increased
in brass beyond 45%, then gamma phase is appeared in its
structure. This structure is extremely brittle,
rendering an alloy which makes
it unsuitable for general
engineering purposes.
The various types of brasses
are discussed as under.

 Red Brass

Red brass is an
important material used for heat conducting purposes. Itcontains Cu = 85% 
Zn = 15%.

Properties

Red brass is having excellent corrosion
resistance and workability. It possesses tensile strength ranging from 27-31
kg/mm 2. Percentage elongation of this brass is 42-48.

Applications

Red brass is mainly utilized for
making, heat exchanger tubes, condenser, radiator cores, plumbing pipes,
sockets, hardware, etc.

Yellow Brass or Muntz Metal

Yellow brass is also known as muntz metal. It contains Cu  
=  60%, Zn 
 40%

Muntz metal is having high strength
and high hot workability. It is having tensile strength 38 Kg/mm
2 (approximately). The percentage elongation of
this brass is 45%.

Applications

Yellow brass or muntz metal is suitable for hot working
by rolling, extrusion and stamping. It is utilized for making small
various components of machine and electrical equipment such as bolts,
rods, tubes, valves
and fuses. This metal is utilized for making for pump parts,
valves, taps, condenser tubes, sheet form for ship sheathing (because
of excellent corrosion
resistance).

Cartridge Brass

It contains 70%
Cu and 30% Zn. It is having good
combination of strength and ductility. It
is having tensile strength between 31-37 kg/mm
2. Percentage elongation of this brass is 55-66%. It is
generally processed into rolled sheets. The metal alloy can be easily cold worked using cold working processes
such as wire drawing, deep drawing and pressing.

Applications

It is utilized for making for making tubes,
automotive radiator cores,
hardware fasteners, rivets, springs,
plumber accessories and in tube manufacture.

Admiralty Brass

It contains Cu= 71%, Zn= 29%, Sn= 1 %

Properties


1.  Admiralty brass is highly
resistant to corrosion.
2.  It is highly
resistant to impingement attack of sea water.
3.  It
is having tensile
strength 30 kg/mm
2 (approx.).
4.  It
can be cold worked
5.  It possesses good corrosion resistance to sea water corrosion.
6. The
percentage elongation of admiralty brass
is 65%.

Applications

Admiralty brass is utilized
for making condenser tubes in marine
and other installations. It is used for making
plates used for ship building. It is utilized also for making bolts, nuts,
washers,
condenser plant and ship fittings parts,
etc.

Naval Brass

Navel brass is commonly used for making marine
components. It contains 
Cu= 59%, Zn= 40%, Sn= 1 %

 

Properties

Properties of naval  brass
are similar to muntz metal. As 1% zinc is replaced by 1% tin in
Muntz metal to make navel brass, corrosion resistance of this material to sea
water is significantly improved. The percentage elongation of navel brass is 47% and its tensile strength is 38 kg/mm
2 (approx.).

Applications

Navel brass is commonly utilized for making
marine hardware casting, piston rods, propeller shafts, welding rods etc. 

Manganese Brass

Manganese brass is sometimes also called manganese
bronze. It contains 
Cu= 60%, Zn= 38%, Sn= 0.5 %, Mn= 0.5%, Fe= 1.0%.

 

Properties

Manganese brass possesses sufficient toughness
and good corrosion resistance. It is very active in reducing the oxides of
other metals.

Applications

Manganese brass is utilized for making
hydraulic rams, valves and cylinders, tubes, pump rods, propellers, bolts, nuts
etc. 

Iron Brass or Delta Metal 

Iron brass or delta brass contains Cu= 60%, Zn= 37%, Fe= 3%

Iron brass or delta metal is
hard, strong, tough, and having good corrosion resistance. 
It can be casted easily.


Applications

If corrosion is to be resisted in mild steel,
then some amount of iron brass or delta metal is added in mild steel. 

 Gilding Brass


Gilding brass is a very cheap metal for making
jewellery, decorative and ornamental products. It generally contains 
Cu   =
 85%, 
Zn   15%

Applications 

Because of better appearance
this metal is commonly used for
jewellery, decorative
and ornamental work. 

Free Cutting Brass


Free cutting
brass contains 
 Cu= 57.5%, Zn= 40%, Pb= 2.5%
Free cutting brass is highly machinable and it does not
allow bending.

Applications

Free cutting brass is used for
making cast, forged or stamped blanks to be used for further machining such as
high speed turning and screwing.

Lead Brass

Lead brass is also known as cloak brass which contains Cu= 65%, Zn= 34%, Pb= 1%

 

Applications

Lead brass or cloak brass is used in making small gears
and pinions for clock work.

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