Comparison between hot working and cold working processes can be done in aspects like carried out temperature, stress set up, tolerances, hardening, deformation, surface finish, improved properties, cracks formation.
| S.no |
Hot Working
|
Cold Working
|
|---|---|---|
| 1 | Hot-working is carried out above the recrystallization temperature and below the melting point. Hence the deformation of metal and recovery take place simultaneously. | Cold working is carried out below the recrystallization temperature. As such, there is no appreciable recovery. |
| 2 | No internal or residual stresses are set up in the metal in the hot working process. | In the cold working process, internal or residual stresses are set up in the metal. |
| 3 | If cracks and blow boles are present in the metal, they can be finished through hot working. | In cold working, the existing cracks propagate and new cracks may develop. |
| 4 | Close tolerance can not be maintained. | Better tolerance can be easily maintained. |
| 5 | The surface finish of the hot working process is comparatively not good. | The surface finish of the cold working process is better. |
| 6 | It results in improvements of properties like impact strength and elongation. | It also results in improvements of properties like impact strength and elongation. |
| 7 | If the hot working process is performed properly, it does not affect ultimate tensile strength, hardness, corrosion resistance yield strength and fatigue strength of the metal. | It improves ultimate tensile strength, hardness, yield strength but reduces the corrosion resistance of strength of the metal. |
| 8 | Due to recrystallization very negligible hardening of metal takes place. | Since cold working is done below recrystallization temperature the metal gets work hardened. |
| 9 | Hot-working refines metal grains resulting in improved mechanical properties. | Most of the cold working processes lead to distortion of grains. |
| 10 | Due to higher deformation temperatures, the stress required for deformation is much less. | The stress required to cause deformation is much higher. |
