Describe the various mechanical properties of materials in short. Or Write about the various mechanical properties of metals.Ripunjay Tiwari
Ans. The material properties which are associated with the ability of the
material to resist mechanical forces and loads are known as mechanical
properties. The mechanical properties are a measure of the strength and lasting
characteristics of a material in service. Some important mechanical properties
are described below –
(i) Strength- The resistance offered by a material on application
of external force or load is known as strength. Depending on the type of load
applied, the strength could be compressive, tensile or shear.
Due to load, the material is elastically deformed, which is known as strain.
The resistance offered by the material is also known as stress. Stress can
be defined as
The tensile strength of a material is measured by a tensile test carried out
on a universal testing machine.
(ii) Elasticity- Elasticity of a material is its power of coming back
To its original position after deformation when the stress or load is removed.
In other words, elasticity is that property of a material by virtue of which
deformation caused by applied load disappears upon removal of the load.
Elasticity is a tensile property of the material.
(iii) Plasticity – The plasticity of a material is its ability to undergo
some degree of permanent deformation without rupture or failure. The plastic
deformation takes place beyond the elastic limit. This property of a material is
important in forming, extruding, shaping and many other cold or hot working
processes. Generally, plasticity decreases with decreasing temperature. Material
such as steel is plastic at bright heat and lead, clay etc., are plastic at room
(iv) Stiffness-Stiffness is defined as the resistance of a material to
elastic deformation or deflection. It is also called rigidity. A material which
suffers more deformation under load has a low degree of stiffness or rigidity.
For example, suspended beams of aluminium and steel may both sufficiently
strong to carry the required load but the aluminium beam will bend or deflect
further. In other words, the aluminium beam is less stiffer than steel beam. If
the material follows Hook’s law, its stiffness or rigidity is measured by the
Young’s modulus E. The higher the value of Young’s modulus, the stiffer the
In compressive and tensile stress, it is known as modulus of elasticity or
modulus of stiffness; in volumetric distortion, it is called the bulk modulus.
The term flexibility is sometimes used as the opposite of stiffness.
(v) Ductility – It is the property of a material which enables it to
draw into the shape of wire. Mild steel is an example of ductile material. The
percentage elongation and the reduction in area in tension is often used as
empirical measure of ductility.
A material is generally said to be ductile if the percentage elongation is
more than 5 in a gauge length of 50 mm. Mild steel, copper, aluminium, zinc,
nickel, tin etc., are ductile metals.
(vi) Malleability – This is the property by vil1ue of which a material
may be hammered or rolled into thin sheets without rupture. This property
increases with increase of temperature. Aluminium, copper, tin, lead, steel
etc., are malleable metals.
(vii) Toughness (or Tenacity) – Toughness is the strength with which
the material opposes rupture. It is a measure of the amount of energy, a material
can absorb before actual fracture or failure takes place. Mild steel is tougher
(viii) Brittleness– Brittleness of a material is the property of breaking
without much permanent distortion. In other words, lack of ductility is
brittleness. If a body breaks easily when subjected to shocks it is said to be