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Further observation was carried out particularly in an attempt to determine the presence or absence of surface oxide on the intergranular stress corrosion cracks. The results are shown in Fig. 14. There were many small open cracks on the electropolished surface. The detailed observation of the opened cracks is shown in Fig. 14. These observations were consistent with the prior observations. Fig. 14 shows a crack at the oxide film, and that crack was associated with an intergranular crack in the metal underneath, ie the crack in the oxide propagated along the metal grain boundary. This region of IGSCC was not covered by an oxide film, which was visible by SEM. The grains at the crack tip were detached from the tearing region, ie there was often a crack between the IGSCC region and the tearing region. The IGSCC region extended about two or three grains, which means the stress corrosion cracks did not grow to be very long.