Residual stress measurements in laser shock processed materials

Author:  P.Muñoz, J. Ruiz-Hervias, J.A. Porro and J.L. Ocaña
Source:  Conf Proc 2014: ICSP-12 Goslar, Germany (pgs.250-255)
Doc ID:  2014084
Year of Publication:  2014
Abstract:  
Laser Shock Processing (LSP) is employed to produce compressive residual stresses in the subsurface region of the material by using high-intensity laser impulses to increase the durability of machinery or structural components subjected to fatigue or stress corrosion cracking. By using this technique it is intended to increase the maximum depth at which compressive residual stresses are present in the material with respect to the values obtained with traditional shot peening. In addition, as the supplied energy can be accurately controlled, it is expected that the repeatability of the residual stress field would be improved. However, sometimes tensile residual stresses have been found at the surface of LSP samples. Consequently, it is important to understand the generation of residual stresses during LSP in order to explain this behavior. In this work, residual stresses were measured by X-ray diffraction both at the surface and at the subsurface region (using electro-polishing up to 400 micron depth) of several metallic materials subjected to LSP. The effect of the pulse density on the residual stress field is discussed for all tested materials.