Corrosion-fatigue initiation processes in a maraging steel

The fatigue-crack initiation behaviour of an 18% Ni maraging steel has been examined in both air and 3·5% sodium chloride solution. Cracks were found to initiate almost exclusively at iron silicate inclusions, in both air and sodium chloride solution, although cracks initiated considerably more easily in the corrosive environment. The crack-initiation behaviour in air is conslstent wah debondlng mechanisms, and it isproposed that debonding of inclusions by selective corrosion of the metal/inclusion interface could be responsible, at least in part, for the deleterious effect of the sodium chloride solution.