Mechanical Properties of Metals

Mechanical Properties of Metals

Those which are preferred with the capacity of the material to oppose mechanical forces and load. The mechanical properties of the metal includes ductility, brittleness, malleability,strength,stiffness, elasticity, plasticity,  toughness, resilience, creep and hardness. We shall now discuss those properties as listed below:

1. Strength.
 The ability of a material to oppose the externally applied forces without breaking. The internal resistance reffered by a part to an externally applied force is called stress.
2. Stiffness.
The ability of  a material to resist deformation over stress. The modulus ofelasticity is a measure of stiffness.
3. Elasticity.
 The  property of a material to regain its original shape after deformation when
the external forces are released. This property is used for materials used in equipments and machinery.
It may be proved that rubber is less elastic than steel.
4. Plasticity.
 The property of a material which retains the deformation developed under load permanently. This property of the material is useful for forgingshop, in stamping picture on coins and in jewelry making.
5. Ductility.
 The property of a material which can be drawn into thin wire with the application of a tensile force. A ductile material must be both strongest and plastic. The ductility is generally calculated by the terms, percentage elongation and percentage reduction in area. The ductile material
commonly used in engineering practice  are aluminium, nickel,steel, copper,zinc, tin and lead.
6. Brittleness.
 The property of a material just opposite to ductility. It is the property of failure of a material with some permanent distortion. Brittle materials when applied to tensile loads, cracks
out without giving  some elongation. Glass is a brittle material.
7. Malleability.
 The property of a material which can be made into thin sheets by applying external forces. A malleable material may be plastic but it is not necessary to be more strong. The malleable materials usually used in engineering practice which are wrought iron, copper ,lead, soft steel and aluminium.
8. Toughness.
 The property of a material to oppose fracture due to higher impact loads . The toughness of the material increases when it is cooled. It is calculated by the
amount of energy that a unit volume of the material has absorbed after being stressed upto the point of failure. This property is necessary
in parts subjected to shock and impact loads.
9. Machinability.
The property of a material which can be machined easily. The machinability
of a material can be calculated in a number of Process such as comparing the tool life for cutting
Various materials or force required to remove the material at some given rate or the energy required to be removed a unit volume of the material. It may be noted that steel can't be easily machined than brass.
10. Resilience.
 The property of a material to absorb energy and to oppose shock
and impact loads. It measures the amount of energy absorbed per unit volume within elastic limit. This property is necessary for
spring materials.
11. Creep.
 When a part is placed to a constant stress at higher temperature for longer
period of time, it would undergo a slower and permanent deformation called creep. This property is necessary in designing internal combustion engines, boilers and turbines.
12. Fatigue.
When a material is subjected to repeated stress, it fail at
stress below the yield point stress. That
type of failure of a material is known as
fatigue. The failure is occurred by means of a progressive crack formation which are fine and of very small size. This property is Used in designing shafts, connecting rods, springs, gears, etc.
13. Hardness.
 It is a very necessary property of the metals and has a various types of meanings.It includes many different properties such as resistance to wear, scratching, deformation and
machinability etc. It also mean the capacity of a metal to cut other metal.

We hope that you have learned about the Mechanical Properties of Metals
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