Reverse bend, constant deflection fatigue experiments
were conducted in natural sea water at 1850 cycles per minute
(cpm) to investigate the response of 1018 notched steel to
concurrent cyclic loading and cathodic polarization. For
comparison purposes S-log N curves were also determined in
air and high purity argon. These indicate that the endurance
limit established in sea water by cathodic polarization at
-0.85 volts, Saturated Calomel Electrode (SCE), is greater
than in either air or argon. Two mechanisms are considered as
responsible for this behavior.
1. Presence of carbonate and hydroxide deposits
coupled with increased alkalinity at non-propagating
crack tips.
2. Adsorbed OH- layer at non-propagating crack tips.