Behavior of fatigue crack growth of welded specimens is investigated for SA508 CL. la(nuclear reactor pressure vessel forging steel). Tests are performed for three kinds of CCT specimens; unwelded, longitudinally butt welded and transversely butt welded specimens. During this work, a controller is constructed to controll hydraulic fatigue testing system. All the parts used are obtained in domestic markets.
From the tests on the unwelded specimens, longitudinal-welded specimens, it is found that the effective range of stress intensity factor Δ$K_{eff}$ can successfully describe the fatigue crack growth in the base metal regardless of the residual stress. The tests on the transverse-welded specimens show that the fatigue crack growth in the weld metal is also described by the effective stress intensity factor range Δ$K_{eff}$. In clusion, the fatigue crack growth of the welded specimens depends upon Δ$K_{eff}$ only.
