Generation of intergranular strain on laser peened surface

Suzuki, Hiroshi  ; Sano, Kenji*; Tanaka, Hirotomo*; Akita, Koichi*

In this study, the intergranular effect generated in a laser peened surface of a ferritic steel was evaluated using neutron diffraction. The residual stress distribution from the surface to 1 mm depth was obtained by the strain distributions measured using the 110, 200 and 211 reflections. The residual stress distributions derived from the strains of the 110 and 211 reflections were good agreement, while that of the 200 reflection, which is sensitive to the intergranular effect, indicated larger compressive stress by 100 MPa to 200 MPa in the surface layer until 0.8 mm depth from the surface. It is probably intergranular effect, so that the residual stress measurement with consideration of the intergranular effect may be required to evaluate the residual stress generated in the surface layer of the surface treated sample such as the laser peening, the shot peening and so on.