Introduction Hot Forging
- Introduction Hot Forging Cold Forging
Hot forging and cold forging are two different metal forming processes that deliver similar results. Forging is the process of deforming metal into a predetermined shape using certain tools and equipment—deformation is accomplished using hot, cold, or even warm forging processes. Ultimately, the manufacturer will look at a number of criteria before choosing which type of forging is best for a particular application.
- The Hot Forging Process
- When a piece of metal is hot forged it must be heated significantly. The average forging temperature necessary for hotforging of different metals is:
- Up to 1150 degrees Celsius for Steel
- 360 to 520 degrees Celsius for Al-Alloys
- 700 to 800 degrees Celsius for Cu-Alloys
During hot forging, the temperature reaches above the recrystallization point of the metal. This kind of extreme heat is necessary in avoiding strain hardening of the metal during deformation. In order to prevent the oxidation of certain metals, like super alloys, a type of hot forging called isothermal forging is a good choice.
In isothermal forging, the metal deformation occurs within a highly controlled atmosphere, similar to that of a vacuum.
- Hot Forging Considerations
Traditionally, manufacturers choose hot forging for the fabrication of parts that have a greater influence in the technical arena. Hot forging is also recommended for the deformation of metal that features a high formability ratio.
- Other considerations for hot forging include:
- 1. Production of discrete parts
- 2. Low to medium accuracy
- 3. Scale Formation
- 4. Low stresses or low work hardening
- 5. Homorgenized grain structure
- 6. Increased ductility
- 7. Eliminiation of chemical incongruities
- Possible disadvantages of hot forging include:
- Less precise tolerances
- Possible warping of the material during the cooling process
- Varying metal grain structure
- Possible reactions between the surrounding atmosphere and the metal