Effect of rolling ratio on localized corrosion, especially stress corrosion cracking, crevice corrosion and pitting corrosion of austenitic SUS304 and SUS316 stainless steels in chloride solution was electrochemically studied. The susceptibility of stress corrosion cracking was evaluated by observing crack after holding at constant potential in 0.1wt.% sodium chloride solution at 353K. Electrode potential of stainless steels in which stress corrosion cracking was observed under microscope was shifted toward less noble direction by rolling. Time to failure for rolled steels was more shorter than that for steels without working. The cracks observed propagate along grain boundaries. Type of cracks was intergranular stress corrosion cracking (I.G.S.C.C.) in all cases. Repassivation potential, E_{R, CREV} for crevice corrosion and pitting potential of two steels in 0.1wt.% sodium chloride solution at 353K were moved toward less noble direction with increasing the rolling ratio.

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We studied on deterioration process of urushi films by accelerated weathering test. Three kinds of samples were prepared, each sample had different dispersion state of water-soluble component with laccase and polysaccharide. Ki-urushi (as a bad dispersion state of water-soluble component), Sugurome-urushi made from that Ki-urushi by usual bowl in urushi purification factory (H-urushi : as a normal dispersion state of water-soluble component) and other Sugurome-urushi made from that Ki-urushi by three-roll mill (R-urushi : as a good dispersion state of water-soluble component) were prepared. As a result, film thickness decreased with the increase of testing time by weather-meter-test. Consequently, we considered that the deterioration was proceeded such as deleting from surface layer by UV and shower. Further, in deteriorating, it is proved that dispersion state of water-soluble component influenced gloss very much, but had no effect on the decreasing velocity of film thickness. From the results presented above and surface analyses by ATR method of FT-IR and observation by SEM, in deterioration process of urushi film, urushiol at the thin surface layer was decomposed and changed to low molecular weight by UV radiation. Further, this deteriorated urushiol layer and water-soluble polysaccharide were swept by shower, in result the film thickness decreased.

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