Non – Ferrous alloys—BRASS

P. MOHAN BHARATHY

BRASS Brass is a metal alloy made of copper and zinc. Brass has a muted yellow colour, somewhat similar to gold.  By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses. It’s melting point is 940OC Brass has higher malleability than bronze or zinc The major constituent of brass is Cu (50-90%) and Zn (20-40%).

Microstructure of rolled and annealed brass

Properties:Higher malleability than zinc or copper. Low melting point (900 c)corrosion resistantGood conductorNot as hard as steel.It is yellow in colour.It’s weight is 380-450/kgRe-cyclable• Yield Strength 250 to 500 MPa

Copper zinc alllloys (brasses)Copper and zinc form solid solution up to ~39%

zinc at 456c, giving a wide rage of properties.Sn, Al, Si, Mg, Ni, and Pb are added elements,

called ‘alloy brasses’.Commercially used brasses can be divided into

two important groups:1) α brasses (hypo-peritectic)- with α structure

containing upto ~35% Zn.2) α+β brasses (hyperperitectic)- with α+β two

phase structure, based on 60:40 ratio of Cu and Zn

Phase diagram of Cu-Zn system

α- BRASSESα phase – FCC structureα–brass-with less than 35% zinc, are

malleable, can be worked cold, and are used in pressing, forging, or similar applications.

They have fairly good corrosion resistance.The α-brasses are divided into two groups: 1) Red α- brassses (5-20% zinc) 2) Yellow α-brasses (20-30 % zinc)

Red α- brasssesAlloy name Copper

(%)Zinc (%)

Other Notes

Gilding metal

95 5 Softest type of brass commonly available. Gilding metal used for "jackets", making coins, medals, jewlllery base for gold plating. Almost red in color.

Commercial bronze

90 10 It has excellent cold and hot working properties and used for costume jewellery, lipstick cases and grill work.

Red brass 85 5 5% tin, 5% lead

Both an American term for the copper-zinc-tin alloy known as gunmetal

Low brass 80 20 Light golden color, very ductile and musicial instruments.

Yellow α-brassesAlloy name Copper (%) Zinc

(%)Other Notes

Cartridge brass

70 30 Good cold working properties. It is used for cartridge cases, radiator cores and tanks and lamp fixtures.

Yellow brass 67 33 It is used in fasteners and springs.

Admiralty brass

69 30 1% tin It is used for condenser tubes and heat exchangers in steam power plant.

Aluminum brass

77.5 20.5 2% aluminium

Aluminum improves corrosion resistance. It is used for heat exchanger and condenser tubes,marine application.

α+β brasses40% Zn addition provides a complex

structure of α and β phases.α+β brasses also called duplex brass, is

35-45% zinc and is suited for hot working. It contains both α and β' phase; the β'-phase is body -centered cubic and is harder and stronger than α. α-β brasses are usually worked hot.

Pipes

Microstructure of α+β brasses

Cast structure shows dendritesof alpha (dark) in a matrix of beta(white)

Hot rolled Muntz metal sheetstructure of beta phase (dark) andalpha phase (light)

α-β brassesAlloy name Coppe

r (%)Zinc (%)

Other Notes

Muntz metal

60 40 traces of iron

It cannot be rolled, extruded or forged. It is used in valve stem, brazing rods and architectural work.

Naval brass59 40 1% tin It is used in marine

environment and used in propeller shafts, piston rods and valve stems.

Leaded brass

62 35 3% Lead It is used for improved machinability and automatic screw machine stock, lock parts and gears.

High tensile brass

58.5 39 1%Fe,0.3% Mn,

It has a tensile strength of 400N/mm2 and an elongation of 33%. It is used to make pump rods, stampings and forgingfor automomobile fittings.

BrassesAlloy Name

Copper%

Zinc% others Notes

Abyssinian gold

90 10

Lead-free brass

85 14.5 <0.25% lead

Manganese brass

70 29 1.3% manganese

Most notably used in making golden dollar coins.

Nickel brass70 24.5 5.5%

nickelUsed to make pound coins in the pound sterling currency

Nordic gold89 5 5%

aluminium, 1% tin

Used in 10, 20, and 50 cents euro coins.

• Superb colour and texture• Will accept a mirror-like polish• Will not corrode• Can be manufactured as rod, profile, tube, plate,

sheet, foil and wire• Good strength and ductility• Easily processed by casting, extruding, rolling,

drawing and hot stamping• Excellent machining qualities• No degradation in sunlight• Will not soften in high temperatures (up to 200oC)Brass is cost-effectiveNo plating or painting required

Advantages:

DISADVANTAGESBrass requires a good deal of maintenance since

it is prone to a blackish tarnish. 

Disadvantages of Brass DoorsThese doors can be scratched or dented which

gives bad look.Brass doors are suitable for only interiors as

they fade away in harsh weather conditions.They require polishing to protect their surface.Color of brass doors fades with the passage of

time.These doors have warm feeling in summer and

cold in winter when they are touched.

Applications of Brass:

Because of its gold like appearance it is used in decoration purposes and for making coins.

Due to its acoustic properties, it is used in musical instruments such as horns and bells.

Due to its softness than other metals it is also used in zippers.And it is also used for fittings and tools around explosive gases.It is easy to shape, and resistant to corrosion.Polished brass was used as mirror in antiquity.In every industry, hot sampling are used for example pipe

fittings, domestic taps, radiator valves, gas appliances, windows and door furniture are manufactured by this process.

It is used in electrical applications.

THANKYOU!