Page 127 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

Tungsten (W)

The melting temperature of tungsten is 3380° C. This can be drawn into thin wires.
Due to this reason it is used to make filaments of electric lamps.
Tungsten is used as an alloying metal for the production of high speed cutting tools. High speed steel is an alloy
of 18% tungsten, 4% chromium and 1% vanadium.
Stellite is an alloy of 30% chromium, 20% tungsten, 1 to 4% carbon and the balance cobalt.
Vanadium (Va)
This improves the toughness of steel. Vanadium steel is used in the manufacture of gears, tools etc. Vanadium
helps in providing a fine grain structure in tool steels.
Chrome-vanadium steel contains 0.5% to 1.5% chromium, 0.15% to 0.3% vanadium, 0.13% to 1.10% carbon.
This alloy has high tensile strength, elastic limit and ductility. It is used in the manufacture of springs, gears,
shafts and drop forged components.
Vanadium high speed steel contains 0.70% carbon and about 10% vanadium. This is considered as a superior
high speed steel.

Cobalt (Co)
The melting point of cobalt is 1495°C. This can retain magnetic properties and wear- resistance at very high
temperatures. Cobalt is used in the manufacture of magnets, ball bearings, cutting tools etc. Cobalt high speed
steel (sometimes known as super H.S.S.) contains about 5 to 8% cobalt. This has better hardness and wear
resistance properties than the 18% tungsten H.S.S.
Molybdenum (Mo)

The melting point of molybdenum is 2620°C. This gives high resistance against softening when heated.
Molybdenum high speed steel contains 6% of molybdenum, 6% tungsten, 4% chromium and 2% vanadium. This
high speed steel is very tough and has good cutting ability.
Cadmium (cd)
The melting point of cadmium is 320°C. This is used for coating steel components.
Alloying Metals and Non Ferrous Alloys
Non-ferrous Metals And Alloys

Copper and its alloys
Metals without iron are called non-ferrous metals. Eg. Copper, Aluminium, Zinc, Lead and Tin.
Copper
This is extracted from its ores ‘MALACHITE’ which contains about 55% copper and ‘PYRITES’ which contains
about 32% copper.
Properties
Reddish in colour. Copper is easily distinguishable because of its colour.
The structure when fractured is granular, but when forged or rolled it is fibrous.

It is very malleable and ductile and can be made into sheets or wires.
It is a good conductor of electricity. Copper is extensively used as electrical cables and parts of electrical
apparatus which conduct electric current.

Copper is a good conductor of heat and also highly resistant to corrosion. For this reason it is used for boiler fire
boxes, water heating apparatus, water pipes and vessels in brewery and chemical plants. Also used for making
soldering iron.

The melting temperature of copper is 1083o C.
The tensile strength of copper can be increased by hammering or rolling.

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CITS : WCS - Electrical - Exercise 11