Font Size: 

This paper is devoted to the effect of corrosion on the gigacycle fatiguestrength of a martensitic-bainitic hot rolled steel used for manufacturing off-shoremooring chains for petroleum platforms. Smooth specimens were tested under fullyreversed tension between 106 and 1010 cycles in three testing conditions andenvironments: (i) in air, (ii) in air after pre-corrosion, (iii) in air under real timeartificial sea water flow. The fatigue strength at greater than 108 cycles is reduced by afactor more than 5 compared with non corroded specimens. Fatigue cracks initiate atcorrosion pits due to pre-corrosion, if any, or pits resulting from corrosion in real timeduring the cyclic loading. It is shown that under sea water flow, the fatigue life in thegigacycle regime is mainly governed by the corrosion process. Furthermore, thecalculation of the mode I stress intensity factor at hemispherical surface defects (pits)combined with the Paris-Hertzberg-Mc Clintock crack growth rate model shows thatfatigue crack initiation regime represents most of the fatigue life.