Stress relieving is used as a way of countering the stress induced on a material through previous manufacturing processes such as machining, fabrication and welding. These stresses can lead to deformation or dimension changes if not properly treated.
The stress relieving process involves heating the material to a temperature whereby any stresses 'settle'; however, not high enough that the material is altered on a molecular level. Stress relieving is a common precursor to other finishing processes such as nitrocarburizing, and is performed after all cold working processes have been carried out.
Both ferrous and non-ferrous metals can be stress relieved and the temperature used will depend upon the material. After the stress relieving process has been carried out, the material is usually left to cool at room temperature.
Although stress relieving is both common and necessary, the stresses caused by some manufacturing processes - in particular, welding - can cause the material to warp during or after the stress relieving process. Nonetheless, it is important that weldments are stress-relieved prior to additional secondary operations such as machining.
