Plasticity: The characteristic of the material by virtue of
which it undergoes inelastic strain beyond the strain at
elastic limit is called plasticity.
Ductility: The property of a material by which a material
can be drawn out in tension before it fracture. Ductility
measurement can be done by using tension test.
Elasticity: It is that property of material by virtue of
which it returns to its original dimensions during
unloading.
Malleability: It is a physical property of metals that
defines their ability to be hammered, pressed or rolled
into thin sheets without breaking.
Ductility: The % of elongation of the piece under
nsion indicates its ductility.
The property of a material by which a material can
be drain out in tension before it fracture. Ductility
measurement can be done by using tension test.
Tendency of a material to fracture or fail at relatively
small strain under the application of force, impact
or shock, is called brittleness.
Stiffness is the resistance of an elastic body to
deflection or deformation by an applied force.
Static friction a acts because the body tends to move
when a force is applied on it (i.e., the bodies are
not moving relative to each other).
Dynamic friction (kinetic friction) is the friction
between surfaces which the body moves relative
to one another.
Generally, the order of friction forces are
Limiting friction force > Maximum static friction
force > Dynamic friction force
Coefficient of friction is the ratio of friction force
to the normal force which is acting to the norma
of frictional force surface
Malleability is the property of a materialwhich it
can be beaten or rolled into plates.
It is the ability of a material to be deformed or
spread in different directions.
This is usually caused by compressive forces
during rolling, pressing and hammering action.
Example :
Note :
Copper is both ductile and malleable.
Lead is extremely malleable but not ductile.
The property of a material by virtue of which it
returns to its original dimension during unloading
is called elasticity and the material is called
elastic.
When material is unloaded before elastic limit the
original dimension of the member is regained
instantly and unloading curve will follow the original
Curve.
Ductility is the property of the material that enables
it to be drawn out or elongated to an appreciable
extent before rupture occurs.
The percentage elongation or percentage reduction
in area before rupture of a test specimen is the
measure of ductility.
Normally if percentage elongation exceeds 5%
the material is ductile and if it is less than 5%
the material is brittle.
Example : Lead, Copper, Aluminium, Mild steel
are typical ductile materials.
Mild steel has low carbon content (0.15-0.46% c).
As carbon content increase:
() Ductility decreases
(ii) Ultimate strength of steel increases
(ii) Corrosion resistance reduces.
Stress-Strain Curve for Mild Steel [Low Carbon
Steel-Ductile Steel]
Toughness
The ability of the material to absorb energy till
breaking / rupture / failure takes place is known as
toughness.
It represents the ability to resist fracture.
Area under stress-strain curve upto fracture is called
modulus of toughness.
Modulus of toughness = Strain energy stored upto
fracture per unit Volume of material
Toughness is desirable against impact loading
As failure strain is more in ductile material. Mil
steel is more tough than cast iron.
Note : Hardness
Ability to resist scratch or abrasion.
Surface hardness is measured by carrying out
nondestructive indentation test.
The higher the yield stress, higher is the hardness.
Brittleness
In brittle materials, strain at rupture is much smaller
as compared to ductile material (rupture strain is
elastic).
There is no plastic zone for brittle material.
In brittle materials, rupture occurs without any
noticeable prior change in the rate of elongation.
Brittleness is not an absolute property of material.
A material which is brittle at room temperature is
ductile at elevated temperature.
Properties of Materials
Elasticity
The property of a material by virtue of which, it
returns to its original dimension during unloading
is called elasticity and the material is called elastie
If material is unloaded before elastic limit (B) is
reached, the unloading curve will follow the original
curve. When material is unloaded before elastic
limit, the original dimension of the member is
regained instantly.
Plasticity
The characteristic of a material by which it
undergoes inelastic strain beyond the strain at the
elastic limit is known as plasticity.
Resilience
lIt is the property of a material to absorb energy
when it is deformed elastically and then, upon
unloading to have this energy recovered. Hence
greater the resilience more desirable is the material
for spring action.
The area under stress strain curve with in elastic
limit is called modulus of resilience.
Toughness
Ability to absorb mechanical energy upto failure is
called toughness. It represents the ability to resist
fracture.
Area under stress strain curve upto fracture is
called modulus of toughness.
Hardness
Ability to resist scratch or abration. Surface
hardness is measured by carrying out non-
destructive indentation test. The higher the yield
stress, the higher is the hardness.
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