Q. State difference between elastic and plastic deformation.
Ans. Elastic deformation: Elastic deformation is that the part of the deformed material, when the applied load is removed, would spring to its normal shape. The elastic deformation takes place of low stress and having following characteristic:
(b) Usually very small
(c) Obeys the hook's law i.e. stress is proportional to strain
Plastic deformation: In the plastic deformation, the material will not obeys the hook's law. This deformatio9n is set generally 40% melting temperature of that material and depends on applied load, rate of strain; temperature etc. during the plastic deformation, the metal follows the following relation i.e.
P=k e η
Where p=stresses; k=strength coefficient; η=power factor
1. It is first stage of deformation.
It is second stage of deformation i.e. after the elastic deformation.
2. It disappears after the removal of load.
Not disappear even the load is removed.
3. It is temporary.
It is permanent.
4. It is reversible.
It is irreversible.
5. Elastic deformation is practically small and produced strain in the order of 0.5% only.
Plastic deformation is high and the strain produced is also quite high.
6. Stress-strain relationship is given by a constant.
There is no such well defined constant in plastic deformation.
7. After this next stage is plastic deformation.
After this next stage is plastic fracture.