Advantages of Open Die Forging

1. Higher cross section, and higher length jobs can be forged.
2. Dies are flat mostly, so no die-sinking is needed. Thus, die cost is low.
3. High rate of deformation at impact blow or high pressure.
4. Fibrous structure is obtained. Uniform properties than rolled product.
5. High strength, good ductility and good fatigue strength is obtained.
6. Refinement of coarse grain and structure of ingot.
7. Flaws, e.g., slag inclusions, porosity, etc., gets welded due to heavy working.

Difference between Hot Working and Cold Working

HOT WORKING

1. It is carried out above re-crystallization temperature.
2. Refined and equiaxed structure is obtained.
3. Surface finish is not good as Cold Working because of oxidation and decarburisation.
4. Blow holes , porosity get welded during hot working.
5. Probability of cracking is negligible.
6. Diffusion occurs due to high temperature.
7. It increases ductility and toughness.
8. Dimensional tolerance is high.
9. Oxidation and Decarburisation may occur.
10. High loss of metal due to scaling.
11. Isotropic properties.
12. Less power is required.
13. Severe embrittlement of reactive metals unless protected by protective atmospheres.

COLD WORKING

1. It is carried out below re-crystallization temperature.
2. Distorted grain structure is obtained.
3. Surface finish is good.
4. No chance of welding the blow holes and porosity.
5. Probability of cracking is high.
6. Diffusion does not occur due to low temperature.
7. It increases strength.
8. Dimensional tolerance is low.
9. Oxidation and Decarburisation does not occur.
10. Insignificant loss of metal.
11. An-isotropic properties.
12. More power is needed.
13. No embrittlement.