Because plastic deformation properties are normally enhanced by increasing workpiece temperature, forming operations are sometimes performed at temperatures somewhat above room temperature but below the recrystallization temperature. The term warm working is applied to this second temperature range. The dividing line between cold working and warm working is often expressed in terms of the melting point for the metal. The dividing line is usually taken to be 0.3Tm, where Tm is the melting point (absolute temperature) for the particular metal.
The lower strength and strain hardening, as well as higher ductility of the metal at the intermediate temperatures, provide warm working with the following advantages over cold working:
- lower forces and power;
- more intricate work geometries possible, and
- need for annealing may be reduced or eliminated.