6. Conclusions

The purpose of surface treatments for prestressing is to introduce compressive stresses into the surface layers of metal parts over thicknesses of up to several millimeters. Their main aim is to improve the resistance of parts subjected in service to mechanical stresses that vary over time, or to corrosion under static stress.

They are based on deformation heterogeneity arising from the location of a primary source of deformation in the surface zones of the part. The core of the part, which represents the largest mass, opposes the "free" dimensional variation of the skin, thus generating a self-balancing field of residual macrostresses. The primary sources of deformation are obtained by two types of treatment.

Mechanical treatments act by plastic deformation of surface layers and are applicable to all materials exhibiting elastoplastic behavior....