The effects of pulsating stress on the resistance to stress corrosion cracking of AISI 304 stainless steel were investigated.
The results are summarized as follows;
(1) In the range of very slower cyclic speed for pulsating stress such as 0.03c.p.m., the effect of stress pulsation is negligibly small, and the time to failure can be obtained by the calculation based on the accumulation of only the static damage which is produced by each instantaneous value of pulsating stress. Namely, Miner's cumulative damage law is applicable.
(2) In the range of cyclic speed between 0.03c.p.m. and 30c.p.m., the faster the cyclic speed is, the shorter the time to failure becomes than the time calculated by Miner's law. This fact means that the dynamic damage also appears besides the static damage described above. So, assuming that the failure occurs at the time when the sum total of both static and dynamic damage ratios is equal to one, we calculated each ratio of static and dynamic damage to the total damage. As a result of this calculation, it becomes clear that the static damage rate decreases and the dynamic damage rate increases with the increase of cyclic speed.

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The corrosion survey of steel sheet piles at Toyama, Etomo and Yasuki Harbors have been carried out, and the following results were obtained.
(1) Corrosion tendencies of steel sheet piles could be roughly divided into the following three types:
(a) Corrosion was concentrated only on the flat portion of outward facing steel piles within the range of about 30cm under mean low water level, and their corrosion rates were 0.5 to 1.0mm/yr.
(b) In sea water, corrosion rate of the flat portion of outward facing steel piles was greater than that of inward facing steel piles. This tendency was most conspicuous directly under mean low water level, and corrosion rates of the flat portion of convex steel piles were 0.1 to 0.2mm/yr.
(c) Corrosion rate of steel sheet piles did almost not depend on their shape and elevation.
(2) Since, at structures with steel sheet piles, tie rods had been connected generally with the flat portions of inward facing steel sheet piles, the structures didn't collapse at all even in the case of corrosion of type (a) mentioned above.

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