Important Mechanical Properties of Metals

MECHANICAL PROPERTIES OF MATERIALS

Property of Metals

1. STRENGTH

                  It is the ability of  a material to resist the externally applied forces without breaking or yielding. 

2. STIFFNESS

              It is the ability of a material to resist deformation under stress. The modulus of elasticity is the measure of stiffness.

3. ELASTICITY

                 It is the property of a material to regain its original shape after deformation, when the external forces are removed. This property is desirable for materials used in tool and machines. It may be noted that steel is more elastic than rubber.

4. PLASTICITY

                     It is the property of a material which retains the deformation under load permanently. This property of a material is necessary for forging, in stamping images on coin, and in ornamental work.

5. DUCTILITY  

                     It is the property of a material enabling in to be drawn into wire with the application of a tensile force. A ductile material commonly used in engineering practices are mild steel, copper, aluminium, nickel, zinc, tin and lead.

6. BRITTLENESS

                   It is the property of a material opposite to ductility. It is the property of breaking of a material with little permanent distortion. Cast iron is a brittle material.

7. MALLEABILITY

             It is the special case of ductility which permits material to be rolled or hammered into thin sheet. It use in engineering practice are lead, soft steel, wrought iron, copper and aluminium.

8. TOUGHNESS

                   It is the property of a material to resist fracture dueto high impact loads like hammer blows. The toughness of a material is decriges when it is heated. This property is desirable in parts subjected to shock and imppact loads.

9. RESILIENCE

                  It is the property of a material to avsorb energy and to resist shock and impact loads. This property is essential for spring material.

10. CREEP

                  When a part is subjected to a constant stress at high temperature for a long period of time, it will undergo a slow and permanent deformation called creep. 

Consider to design:- Internal combustion engine, boilers and turbines.

11. FATIGUE

            When a material is subjected to a repeated stresses, it fails at stresses below the yield point stresses. Such type of failure is known as fatigue.

Consider to design:- shaft, connecting rods, spring, gear etc.

12. HARDNESS

                  It is very important property of a metals and has a wide verity of meaning. It has many different type of properties such as resistance to wear, stretching, deformation and machinability etc. It also means the ability of material to cut another material.