**4. Techniques for controlling or reducing residual stresses and distortions**

The relief of residual stress in welding has as premise the production of a rearrangement of atoms or molecules from their position of momentary equilibrium, from where the material leaves from a larger state to another of lower tension (lower potential energy), a more stable position. The analysis of residual stress and welding distortion, seen from a historical perspective, developed largely independently of each other, although, from the physical point of view, they are closely related [11].

To design and manufacture a structure with the least number of defects it is essential to have: an appropriate design; an appropriate selection of materials; suitable welding equipment and procedures; good manpower; and strict quality control [1]. The authors [64] showed that the procedures for reducing RS's are directly linked to the reduction of deformations generated during the joining process. There are several examples of methodologies that can be used to perform the relief of RS's, classified into three major categories: Thermal, Mechanical and Chemical, which can be performed before, during and after welding. There are many stress relief techniques that can be classified as conventional, due to their extensive use and the most varied applications in welded components, such as: hammering, heat treatment (pre- and post-heating), shot peening, mechanical tensioning, among others. However, nonconventional alternative techniques will be approached.
