抄録
Corrosion resistance of cold rolled, Zn-Fe and Zn-Ni alloy electrogalvanized steel sheets with and without ED-painting was investigated by means of salt dipping(DIP), saltspraying(SST) and cyclic corrosion test (CCT) including DIP, SST, drying(DRY) and humidifying(WET). From these results, the role of the unit test of CCT in corrosion behaviour of these materials was discussed.The results obtained are summarized as follows ;
(1) In the case of unpainted specimens, SST is very aggressive environments compared with DIP. The combination of DRY or WET with DIP increased both the weight loss and the corrosion depth of the specimen. However when it was combined with SST, the weight loss increased and the corrosion depth decreased
(2) DRY and WET in corrosion behaviour of ED-painted specimens played an inverse role in unpainted specimens. In particular, WET accelerated the paint exfoliation which affected the perforation corrosion.
(3) Zn-Fe and Zn-Ni alloy electroplated steels showed a good corrosion resistance compared with the cold rolled steel in all kinds of tests.
