uses
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uses
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uses
properties
composition
uses
properties
composition
example
definition
overcome by adding
properties
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example
Cast alloy
wrought alloys.
based on
importance
properties
definition

Alloys

combining two or more metallic elements to give a greater strength

Harder,less malleable,low melting point.
Low electrical conductivity.
Resists corrosion and action of acids.

Increases hardness of a metal,
Modify the colour of the metal,
Good casting of the metal,good
Greater strength,
Modify the chemical activity,
Low melting point,

Micro structure

presence or absense of iron.

Principal metals

alloys of Cu+Zn = brasses
alloys of Cu+Sn = bronzes
alloys of Al =duralium

ferrous alloy
non-ferrous alloy.

Alloys that are amenable mechanical deformation

Alloys that are so brittle that forming or shaping by appreciable deformation is not possible

steel

Plain carbon steel

Hypoeutectoid steel

Soft/low Carbon steel

0.08% to 0.2%
carbon

making boiler tubes, plates, sheet steel, bolts, nails, wires, screws, gear, wheels etc

Soft, ductile, weldable, Dark bluish with fibrous structure, Low tensile strength, Shock resistant
Not susceptible to heat treatment

High/Hard Carbon steel

0.5% to 0.8%

making wheels for railway bogies, cushion spring, dies, screws etc

Welded with care
Can be tailored to desired hardness

Medium Carbon Steel

0.2% to 0.5%
carbon.

machine parts, turbine motors, railway angle, wheels, gears, hydraulic fitting, connecting rods, automobile engine parts

Tougher and harder than mild steel
Good machinability and less weldability
Good strength
Can be hardened by heat treatment

Hypereutectoid steel

Very High Carbon/Hard Steel

0.8% to 2.0%

for manufacturing various types of tools such as; hammers, drills, etc;

High strength
Can be hardened, toughened and tempered easily
Possess wear resistance
Welded easily

↑ brittleness
↑ carbon content
↓ductility
no proper corrosion resistance
not deeply hardened.

Ni,Cr,Co,Mn,Mo,V

alloy steel/special steel

Steel containing specified amounts of alloying elements other than carbon is known as alloy steel

Chromium
Copper
Manganese
Nickel
Tungsten
Molybdenum

Ferrous alloy

Stainless steel

Heat treatable
stainless steel

C=1.2%
Cr=>12-16%

Magnetic, tough & can be worked in cold condition
Possess less strength at high temperature
Resistant to corrosion

1. Can be used up to 800⁰C
2. Good resistant towards weather & water
3. In making surgical instruments, scissors, blades,etc.

Non-heat treatable
stainless steel

Magnetic type

C=1.2%
Cr=>12-16%

1. Can be forged, rolled & machined
2. Resist corrosion

Used in making chemical equipments
and automobile parts.

Non--magnetic type

Cr=18-26%
Ni=8.21%
c=0.15%
total%Cr&Ni>=23%

1. Resistance to corrosion.
2. Corrosion resistance is increased by adding molybdenum

In making household utensils, sinks, dental & surgical instrument

Nichrome

Ni=60%
Cr=12%
Fe=26%
Mn=2%

1. Good resistance to oxidation & heat
2. High melting point & electrical resistance
3. Withstand heat up to 1000-1100⁰C

1. Used for making resistance coils, heating elements in stoves & electric irons
2. Used in making parts of boilers, steam lines stills, gas turbines, aero engine valves, retorts, annealing boxes.