抄録
62 level block fatigue loadings approximating to the Rayleigh distribution of peak were applied on center cracked transverse butt welded joint specimens in which tensile residual stress was always induced at the crack tips. The test environment was periodically changed between synthetic sea water and ambient air. The fatigue crack propagation rate, da/dn, obtained in this environment became low compared with da/dn in synthetic sea water by increasing the period in the ambient air. The decrease of da/dn occurred from the crack closure due to oxide debris in spite of the high stress ratio condition around the crack tips.
