Service Life Extension of Metal Materials by Direct Pulse Laser Irradiation

Abstract

The development of laser peening without coating（LPwC） in the recent quarter century is summarized. Experiments showed that water on the laser-irradiated material confines ablation plasma and intensifies the pressure beyond the yield strengths of most metals. Time-dependent elasto-plastic FEM simulation reproduced the experimental results of the residual stress depth profile. LPwC significantly reduced the susceptibility of sensitized SUS304 to stress corrosion cracking（SCC） and improved the fatigue properties of SUS316L. LPwC was attempted using a microchip laser with a pulse energy of 1.7 mJ, which introduced compressive residual stresses and enhanced the fatigue properties of A7075 aluminum alloy.