EVOLUTION OF STATISTICAL DISTRIBUTION OF PIT GEOMETRIC PARAMETERS UNDER FATIGUE LOADING

The pits and pit-associated fatigue crack initiation of the offshore structure steel A537cLlhave been investigated under salt water spray condition.The tests were interrupted on sched-ule to make plastic replica of corroded specimen surface on which many randomly distributedpits can be found.The development of the geometric parameters of pits was obtained and thestatistical distributions of these parameters were determined.Instead of depth,the ratio ofdepth to width is the most dominant parameter in relation to crack initiation.Also,the pittingwas enhanced when low frequency or high stress range was applied and although stress rangehas no effect on the nucleation of pits,it can accelerate the initiation of cracks from pits.

EVOLUTION OF STATISTICAL DISTRIBUTION OF PIT GEOMETRIC PARAMETERS UNDER FATIGUE LOADING

The pits and pit-associated fatigue crack initiation of the offshore structure steel A537cLl have been investigated under salt water spray condition.The tests were interrupted on sched- ule to make plastic replica of corroded specimen surface on which many randomly distributed pits can be found.The development of the geometric parameters of pits was obtained and the statistical distributions of these parameters were determined.Instead of depth,the ratio of depth to width is the most dominant parameter in relation to crack initiation.Also,the pitting was enhanced when low frequency or high stress range was applied and although stress range has no effect on the nucleation of pits,it can accelerate the initiation of cracks from pits.