5 Dry Laser Peening: Ultrashort Pulsed Laser Peening …
173
Fig. 5.9 Schematic illustrations of the experimental procedures. a Full-penetration bead-on-plate
laser welding and preparation of fatigue test specimens cut from the laser-welded plate. b Dry laser
peening (DryLP) process using femtosecond laser pulses. c Geometry of the fatigue test specimens
with the weld bead located in the center. DryLP was performed using an x–y automatic stage which
sequentially moved the specimen in a serpentine pattern, as indicated by the red arrows [55]
[105], using the strain scanning method [106] with monochromatic X-rays with a
photon energy of 30.013 keV, as shown in Fig. 5.10. A CdTe detector was used for
the measurements. The residual stress σ was estimated using σ = E(d − d 0 )
d 0 ,
where E is the Young’s modulus of 61.7 GPa, d is the d-spacing of the (311) plane of
aluminum in the welded or DryLPed specimens, and d 0 is the d-spacing of the (311)
plane in the BM of 0.12196 nm. The d-spacing of the (311) plane parallel to the weld
173
Fig. 5.9 Schematic illustrations of the experimental procedures. a Full-penetration bead-on-plate
laser welding and preparation of fatigue test specimens cut from the laser-welded plate. b Dry laser
peening (DryLP) process using femtosecond laser pulses. c Geometry of the fatigue test specimens
with the weld bead located in the center. DryLP was performed using an x–y automatic stage which
sequentially moved the specimen in a serpentine pattern, as indicated by the red arrows [55]
[105], using the strain scanning method [106] with monochromatic X-rays with a
photon energy of 30.013 keV, as shown in Fig. 5.10. A CdTe detector was used for
the measurements. The residual stress σ was estimated using σ = E(d − d 0 )
d 0 ,
where E is the Young’s modulus of 61.7 GPa, d is the d-spacing of the (311) plane of
aluminum in the welded or DryLPed specimens, and d 0 is the d-spacing of the (311)
plane in the BM of 0.12196 nm. The d-spacing of the (311) plane parallel to the weld