LASER GENERATION OF STRESS WAVES IN METAL

Today surface treatments are very important in the mechanical industry to increase the fatigue life of metal components. In addition to clas sical treatments such as shot peening, a new process is being develope d. The laser shock surface treatment permits the creation of plastic s trains and induction of compressive residual stresses in metals. It co nsists in irradiating a metallic sample with a short but intense laser pulse. As a consequence a high temperature high pressure plasma is cr eated at the sample surface. An elastic-plastic wave propagates in the sample, creating plastic strains. The present study deals with the ef fects of laser-induced stress waves on residual stresses, microhardnes s and surface quality of a standard steel (0.55% C). The residual stre sses generated are compressive for a depth of up to 1 mm. With optimum conditions, we can produce homogeneous cover strips without surface d eterioration.