**4.3 Vibratory stress relief (VSR)**

The VSR process has achieved great prominence in the relief of RS's induced by thermal processes, such as welding, casting, but not those induced by cold work, being applied in several materials, low and medium carbon steels, stainless steels and aluminum alloys, not having an expected effect on copper alloys. VSR offers several advantages compared to the PWHT (Post Weld Heat Treatment) process: low time and energy spent, low thermal deformation and no change in the mechanical or metallurgical properties of the material [11, 65]. However, there are numerous conditions that must be considered when using the VSR and PWHT processes. Within the conditions employed by the authors, a lower RS value was obtained for the use of both processes.

The basic premise of this method is the relief of the workpiece RS with a region where the natural stress has been changed. When the part is subjected to vibrations below its new frequency, the metal absorbs energy, gradually redistributing the stresses and the resonant frequency returns to the point corresponding to a residual, or almost free, state [20]. The search for greater productivity for the arc welding process has generated efforts by researchers to develop the VSR process, to act during the welding process, that is, Vibration assisted welding (VAW), which can reduce most expenses related to post-weld vibrations or heat treatments [74].
