Analysis of residual stress state of spring steel wire induced by laser shock processing

The SWOSC-V spring steel wires manufactured by different treatment processes were treated by laser shock processing (LSP) with high power Nd：YAG laser. Residual stresses on inner surface, outer surface and lateral surface were measured by X-ray diffraction (XRD) and principal stresses were calculated. The generation model of laser shock waves in springs was established, and reasons of residual stress generation on spring surface were explained. Residual compressive stresses on each surface of springs were obtained. The changes of residual stress are different between LSP on the annealed spring and the shot blasted spring, and the material hardening by shot peening(SP) is the reason for the different changes of residual stress by LSP.