Low-cycle fatigue crack initiation and propagation from controlled surface imperfections in nuclear steels

Abstract The impact of a controlled surface imperfection on the low-cycle fatigue life in two different steels is investigated. After introduction of a single imperfection with a depth varying from 50 to 350 µm in cylindrical samples, fatigue tests were conducted under fully-reversed total axial strain control in air at ambient temperature. It is shown that the fatigue life is significantly reduced, even in presence of small imperfections. In addition, the use of the potential drop methods provided an assesment of the initiation life and the determination of crack growth rates. Two characteristic crack growth domains were thus identified.