Study of visual inspection and control methods of effectiveness of laser shock-processing

Visual inspection and control methods for the effectiveness of laser shock-processing (LSP) are described first. The surface qualities of LSP areas can be controlled by adjusting the laser parameters and process details by which the difficult technical problems in LSP engineering applications are also solved. The effects of LSP can be evaluated according to surface qualities after LSP, which are quantitatively characterized by three parameters: surface roughness, hollow depth and surface residual stress. The best surface qualities of the samples are achieved when the surface roughness is one to two grades less than or equal to those of an unprocessed area, a very bright shallow hollow is formed and the hollow depth is 6-18 mu m, and high surface residual stresses are produced in the LP area. Only under these conditions can the best LSP effect or fatigue life increment be obtained. The LSP effect can be controlled effectively be means of controlling the surface qualities of LSP zones. The three different control methods are presented and analysed.