1. Modification of surface finish. Residual stresses

1.1 Surface modification

After mechanical surface treatments, the surface finish varies according to the initial condition. If we assume that the initial state is normal fine machining and that surface treatment has been carried out correctly, roller burnishing, burnishing and mandrel burnishing will improve surface finish. Laser impact will, in most cases, preserve the initial surface finish. Shot peening or hammering will deteriorate the surface finish. On the other hand, if the initial state is a welded joint, roller burnishing, shot peening and peening will change the local morphology of the weld to improve the associated properties. Laser shock does not significantly alter the geometry of the welded joint.