抄録
Synchrotron radiation computed laminography (SRCL) was carried out at SPring-8 to visualize a fatigue crack inside a friction stir welded plate and to investigate the propagation behavior. The surface fatigue crack shape and its size reproduced by SRCL agree well with the observation by an optical microscope. A fatigue crack propagation curve obtained by SRCL corresponded with that obtained by replication technique. There are two inflection points on a curve describing the relation between the crack propagation rate and the surface crack length. The cause of the inflection was discussed.
