Mechanical Properties of Metals

Mechanical Properties of Metals.

It associated with behavior of materiel under mechanical load.

1. Strength
2. Stiffness
3. Elasticity
4. Plasticity
5. Ductility
6. Malleability
7. Toughness
8. Brittleness
9. Creep
10. Fatigue
11. Hardness

1.Strength:Strength is the ability of material to resist loads without failure . Its unit is N/m2  or Pa ( pascal) Strength usually expressed as maximum stress or ultimate tensile strength (UTS) ( maximum load per unite area ) 

2.Stiffness:Ability to resist deformation or deflection under a load. Generally with in the elastic limit stiffness is measured by Modulus of Elasticity.

3.Elasticity:Ability to regain its original shape after removal of load.

4.Plasticity:Ability to retain the deformation permanently even after removal of  load.

5.Ductility:Ability to be deformed plastically ( without rapture) under a tensile load is measured in terms of percentage of elongation

6.Malleability:Ability to be deformed plastically ( without rapture) under a compressive  load

7.Toughness:Ability to be absorb energy up-to fracture during the plastic deformation. definition of material toughness is the amount of energy per unit volume that a material can absorb before rupturing. Toughness independent from nature of load hence related with strength and Ductility. 

          Higher the toughness of material, the more is its resistance to shock loads is called impact strength and is usually expressed as

            Impact strenght = E/Ao   k-gm/mm square 

           where E = Energy stored to fracture the specimen in kg-m

                     Ao = Cross-sectional area of the specimen at a notch mm square  

Resilience: The amount of energy absorbed by a material upto the elastic limit is called the Resilience and energy per unit volume is called Modulus of Resilience.

8.Brittleness: Property of sudden fracture without any visible permanent deformation

9.Creep: The slow and progressive deformation of a material with time and temperature under constant stress is called creep. High temperature causes permanent deformation even below the elastic limit. 

10.Fatigue: Failure of material under repeated or reversal stresses is called fatigue. The stress at which the material will operated without failure under infinite cycles of load is know as Endurance limit of Fatigue limit which is below the ultimate strength

11.Hardness: Ability to resist scratching, abrasion, cutting ( or Machining) and indentation ( or penetration).