The impact crack closure retrofit treatment (called ICR treatment) is a technique to delay or arrest fatigue crack growth and enhance residual fatigue life of weld joints including a crack. The treatment is carried out with an air tool to peen plate near the crack and to produce plastic deformation of the steel surface in order to close crack opening. In this study, several fatigue tests on weld joints were conducted under tensile or bending loads in order to verify the life extension effect by ICR treatment. Besides, the effect of the loading types to the life extension was analytically investigated.
