[7p-S45-1~14] 3.7 Laser processing

△ [7p-S45-5] Laser peening effect on various plasma confinement layers

〇Miho Tsuyama¹, Naoya Ehara¹, Kazuma Yamashita¹, Manabu Heya², Hitoshi Nakano¹ (1.Kindai Univ., 2.Osaka-sangyo Univ.)

Keywords:Laser peening, Plasma confinement layer, Laser ablation

Laser peening is a surface treatment technique that improves the mechanical performance of metals. It has been widely used to enhance wear and fatigue resistance in several applications. Laser peening is superior to conventional shot peening since it produces deeper compressive residual stresses and smoother processed surfaces; it is also more suitable for localized processing. These effects are imparted by shock waves that result from the expansion of plasma produced by intense pulsed laser irradiation. At laser intensities exceeding 10⁹ W/cm², a shock wave is generated by the ignition and explosive expansion of plasma. The plastic deformation caused by this shock wave as it propagates through the metal hardens the metal surface and generates residual compressive stresses in the surface region. The effects of the shock wave can be enhanced by coating the surface of the target material with a confining layer that is transparent to the laser light. Such a layer increases the shock wave intensity because it prevents the laser-produced plasma from rapidly expanding away from the surface, thus creating a high-amplitude, short-duration pressure pulse. In this study, effect of control of plasma confinement layer on the laser peening have been investigated.