抄録
In order to prevent corrosion damage, at present, corrosion inhibitor is added to the engine cooling water, as fatigue cracks appear on the surface of the water side of the cylinder cover in marine diesel engines. In the present study, rotating bending fatigue tests were carried out in fresh water similar to actual environments, and the damage from corrosion fatigue on the surface of the surface of the specimens, as well as the effect of the corrosion inhibitor in preventing corrosion fatigue were examined.
The S-N curves or S-T curves in fresh water levelled off but they began to descend again. It was found that the damage due to corrosion fatigue appeared distinctly over a long period even if the stress amplitude was low, and many corrosion pits and microcracks existed besides the main crack. A linear relation was obtained experimentally between the term (k-1) and the term (1/fp), where k is the corrosion effect and fp is the pitting factor. On the other hand, the corrosion fatigue strength in fresh water became equal to or greater than that in air when a sufficient amount of corrosion inhibitor over the critical concentration required for corrosion inhibition was added.
