Product Code: ICAL06_P511

Mechanism of Anisotropic Stress Generation in Laser Peening Process
Authors:
Atsushi Sugihashi, Nippon Steel Corporation; Futtsu-City, Chiba Japan
Koji Hirano, Nippon Steel Corporation; Futtsu-City Chiba Japan
Hirofumi Imai, Nippon Steel Corporation; Futtsu-City, Chiba Japan
Naoya Hamada, Nippon Steel Corporation; Futtsu-City, Chiba Japan
Presented at ICALEO 2006

In laser peening process, several laser pulses are irradiated to cover a certain surface area. It has been reported that when coverage ratio of the beam spots is increased, compressive stress near the surface becomes anisotropic, that is, the two principal stresses in the treated area reach different values. We investigated the mechanism of anisotropic stress generation by basic experiment and by simple model calculation. We measured residual stress on and around a beam spot made by single pulse irradiation. Using the measured residual stress distribution, we simulated residual stress generated after area processing with multiple beam irradiation. Contribution of each beam spot to the stress field was assumed to be additive, and the yielding condition was considered as constraint for the field addition process. The result explains well the generation of anisotropy with increasing the coverage ratio. The model calculation can be applied to control the two principal stresses. This enables us to optimize laser processing conditions, depending on the usage condition of mechanical components.