Abstract
In order to examine SCC of SUS 304 in industrial usage, the double bend-beam tests (four point bending) were carried out in low concentrated MgCl2 solutions under O2 flow, and the relation between SCC and crevice corrosion was examined. The results obtained are summarized as follow:
In the double bend-beam test, cracks appeared on both of the sensitized SUS 304 and the solution-treated one under low MgCl2 concentration and low temperature conditions. The concentration and temperature in these experiments were low enough to be comparable to the SCC initiation condition in industries. The inter-crystalline cracks was observed on the sensitized SUS 304.
Corrosion took place within the crevice between the double bend-beams. The initiation points of SCC were concentrated near the boundary between the crevice corrosion area and the non-corrosion area, where the passive state film seems to be very unstable. The crevice corrosion is considered to induce SCC initiation by concentration of chlorides and destabilization of passive state film in the crevice.
