Difference between hot forging,warm forging and cold forging

Forging is a metal shaping process by application of compressive forces.According to the temperature at which is performed, forging is classified in “hot”,”warm” and “cold”.  Hammers or presses are used to deform the metal/alloy into high strength parts. Mechanical properties of the metal/alloy are improved by forging as it refines its grain structure, making it tougher and stronger.The most common configurations use hammers or presses to squeeze and deform the material into high strength parts. Following is a comparison of cold forging,warm forging and hot forging process.

Hot Forging:

The deformation temperature is higher than the recrystallization temperature.In the process of deformation, softening and work hardening coexist at the same time, but softening can completely overcome the influence of strain hardening, and after deformation,the metal will produce axial fine grain structure such as recrystallization, this deformation is called thermal deformation.Such as open die forging,hot die forging,hot rolling,thermal impact, hot extrusion and so on are thermal deformation.This is one of the most widely used forging processes.

Warm Forging:

Warm forging has a number of cost-saving advantages which underscore its increasing use as a manufacturing method. The temperature range for warm forging of steel extends from above room temperature to below the recrystallization temperature, which is about 800 to 1,800 degrees Fahrenheit, depending upon the alloy. However, the narrower range of from 1,000 to 1,330 degrees Fahrenheit is emerging as the range of perhaps the greatest commercial potential for warm forging of steel alloys. Compared with cold forging, warm forging has the potential advantages of reduced tooling loads, reduced forging press loads, increased steel ductility, elimination of need to anneal prior to forging, and favorable as-forged properties that can eliminate heat treatment.

Cold Forging:

The cold forging manufacturing process is performed at room temperature. The workpiece is squeezed between two dies until it has assumed their shape. To deliver a finished, ready to fit component, the technique includes rolling, drawing, pressing, spinning, extruding and heading.