Forging is a manufacturing process where metal is modeled by applying pressure after making it ductile through the application of heat. Forging techniques are useful for working metal because they enable the desired shape to be given to the steel and also improve its structure, especially because they refine its grain size.
Types of Forging
- 1. Hot Forging– Forging process carried at a temperature above the recrystallization temperature of the metal is called hot forging. This process is done to prevent strain hardening during deformation
- Cold Forging– Forging process carried at a temperature below the recrystallization temperature of the metal is called cold forging. This is done for simple shaped components preferably softer metals/alloys. Compared to cold forging, components produced by hot forging type are more ductile.
- Press Forging– In press forging, a continuous pressure or force is applied, unlike the near-instantaneous impact of drop-hammer forging. In press forging, deformation of complete work-piece occurs while in drop-hammer forging, usually only the surfaces of the work piece in contact with the hammer and anvil deform; the interior of the work-piece remain relatively undeformed.
- Drop Hammer Forging – It is a forging process where a hammer is lifted and then dropped onto the work-piece to deform it according to the die-shape.
There are two types of drop forging
- open-die drop forging and
- closed-die drop forging
In Open-die forging, the work-piece is not fully enclosed while in Close-die forging, the work-piece is fully enclosed.
Benefits of Forgings
In Casting, molten metal is poured into a mold to produce a component of desired shape and allowed to solidify. This solidified part which is also called casting is ejected/broken out of the mold, thus completing the casting process.
Forged steel is usually stronger and more reliable than castings since forging involves alteration of the grain flow imitating the shape of the part. The thermal cycle and deformation process leads to grain refinement and recrystallization which eventually strengthens the resulting steel product.
Why are forged steel products better than castings?
- Forged steel products are tougher than castings.
- Forged steel has higher impact strength than castings
- Forging eliminates the occurrence of shrinkage, porosity, cavities which are usually encountered in castings.
- High strength is attained by the tight grain structure of forgings. Thereby, reducing need for expensive alloys to achieve high strength components.
- The grain structure of forged components offers high wear resistance.