CREEP DEFORMATION OF MATERIAL , ITS OCCURANCE AND TYPES

MECHANICAL TIPS AND STUDY MATERIAL

Creep is slow and progressive deformation of material which is temperature dependent and occurs over long period of time. The load applied is under yield strength.


Creep is inelastic deformation which increases as the time passes as because substance experiences sustained load. For constant temperature and constant stress, the rate of deformation due to creep is approximately constant.


How does creep occur?


Basically it is due to deformation of grain boundary. When one layer of grain slides over other micro-structural layer creating voids or gaps. 

There are factors like temperature, material composition, amount of stress & strain, grain size and time duration under stress which decides the material deformation under creep. 


Types of creep


1) Dislocation creep

2) Dissolution creep
3) Diffusion creep
4) Twinning and Kinking
5) Micro-fracture ; Friction sliding deformation. 

Dislocation Creep


In such creep distortion of structure occurs along the slip plane which is result of breaking down of bond along the slip plane.

Twinning and Kinking


Bending of structure without brittle failure which leads to deformation along that plane.
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