On the behaviour of small fatigue cracks emanating from corrosion pits: Part I – The influence of mechanical factors

Abstract The initiation and propagation behaviour of cracks emanating from corrosion pits in a high strength low alloy steel is investigated by testing pre-pitted specimens in the high cycle fatigue regime in an air environment. This was complemented with finite element analysis of electrochemically generated pit profiles. Fatigue cracks were found to initiate from the mouth of pits due likely to strain localisation at this region. Crack initiation lifetime and fatigue endurance decreased with increasing pit depth. Fatigue behaviour of the steel was found to be crack initiation dominated. A fracture mechanics methodology that provides a satisfactory estimation of critical threshold stresses and threshold stress intensity factor required for fatigue failure from corrosion pits is discussed.