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Q. What is an alloy ?
Ans. :
Alloy :
An alloy is a solid mixture of two or more metals or
non-metals. Alloy must have necessarily,
(i) at least one metal (base metal)
(ii) at least one additional metal or non-metal.
Alloy can also be defined as a solid solution where the
solutes are the alloying elements whereas the solvent is
the element in excess proportion (base or main metal)
Purposes of alloying
The purpose of alloying the metal is to improve,
(i) Hardness
(ii) Tensile strength
(iii) Corrosion resistance
(iv) Castability
(v) Colours While to decrease,
(vi) Melting point
Q. What are the drawbacks of plain carbon steels ?
Drawbacks of plain carbon steels:-
(i) With increasing percentage of carbon, the ductility
decreases and brittleness increases.
(ii) Plain carbon steels cannot be deep hardened on heat
treatment, because due to effect of heat, only surface
of steel gets hardened while the inner layers of steel
remains soft.
(iii) During the use, the mechanical properties of plain
carbon steels get deteriorated at higher temperature.
Thus the uses of plain carbon steels to
make/manufacture various machine parts has
limitation of temperature.
(iv) The corrosion resistance of plain carbon steels is very
low. As a result, this steel has limited use in
manufacturing various machine parts, though
strength and welding characteristics may be suitable.
Q. What are plain carbon steels ?
Plain carbon steels:-
The alloys of iron with other metal (s) or/and nonmetal are known as ferrous alloys. The metal iron
generally forms alloys by mixing with carbon, known
as “Plain Carbon Steels”.
Since these steels essentially contain iron and carbon,
are known as plain carbon steels. The percentage of
carbon in steels ranges from 0.008% to 2%.
