Certain failures of stainless steels interpreted purely in terms of fracture mechanisms may in
fact be closely associated with previous damage caused by localized corrosion. The closeness of the
link between fatigue and corrosion is documented by the case history of compressor blades made of
grade 14Cr17Ni2 (X14CrNi17-2) stainless steel. Fatigue fracturing observed in areas near the blade
root tended to follow intergranular pathways, indicating that some additional mechanism other than
fatigue might be involved. This suspicion was confirmed by electrochemical potentiokinetic
reactivation (EPR) measurements in situ, which revealed sensitization to intergranular corrosion. It
has been found that at the transition between the blade root and the blade proper the surfaces had
been ground and polished too vigorously, heating the subcutaneous layers to within the danger zone
of 400-600°C. Preferential integranular attack in these locations was the initiation mechanism that
provoked a subsequent failure of the blades by fatigue fracture.