Today I am going to tell you main difference between hot
working and cold working. They both are the metal forming processes. When plastic
deformation of metal is carried out at temperature above the recrystallization temperature
the process, the process is known as hot working. If this deformation is done
below the recrystallization temperature the process is known as cold working.
There are many other differences between these processes which are described as
below.
Difference between Hot Working and Cold Working:
|
S.No.
|
Cold working
|
Hot working
|
|
1
|
It is done at a temperature
below the recrystallization temperature.
|
Hot working is done at a
temperature above recrystallization temperature.
|
|
2.
|
It is done below
recrystallization temperature so it is accomplished by strain hardening.
|
Hardening due to plastic
deformation is completely eliminated.
|
|
3.
|
Cold working decreases
mechanical properties of metal like elongation, reduction of area and impact
values.
|
It increases mechanical
properties.
|
|
4.
|
Crystallization does not take
place.
|
Crystallization takes place.
|
|
5.
|
Material is not uniform after
this working.
|
Material is uniform thought.
|
|
6.
|
There is more risk of cracks.
|
There is less risk of cracks.
|
|
7.
|
Cold working increases ultimate
tensile strength, yield point hardness and fatigue strength but decreases
resistance to corrosion.
|
In hot working, ultimate
tensile strength, yield point, corrosion resistance are unaffected.
|
|
8.
|
Internal and residual stresses
are produced.
|
Internal and residual stresses
are not produced.
|
|
9.
|
Cold working required more energy for plastic deformation. |
It requires less energy for plastic deformation because at higher temperature metal become more ductile and soft. |
|
10.
|
More stress is required. |
Less stress required. |
|
11.
|
It does not require pickling because no oxidation of metal takes place. |
Heavy oxidation occurs during hot working so pickling is required to remove oxide. |
|
12.
|
Embrittlement does not occur in cold working due to no reaction with oxygen at lower temperature. |
There is chance of embrittlement by oxygen in hot working hence metal working is done at inert atmosphere for reactive metals. |
These are the main difference between hot working and cold working. If you have any query regarding this article, ask by commenting.