Electro-and Hot-dip Galvanized Steel Sheets Having Cr-free Treatment Layer on the Surface and Cr-free Prepainted Electrogalvanized Steel Sheets

摘要

Various types of coated steel sheets, which are among the major products of Nippon Steel's sheet and coil products, have a chromate layer on those surfaces to ensure good white rust resistance and finish-coat adhesion. However, hexa-valent chromium contained in the chromate layer is one of the environmentally un-friendly materials. in reply to our users' requirement of eliminating such materials, we have recently developed a Cr-free electrogalvanized steel sheet "ZINKOAT-21", a Cr-free hot-dip galvanized steel sheet "SILVERZINC-21", and a Cr-free prepainted electrogalvanized steel sheet "VIEWKOAT-21". The performance of those new products have been found to be enough for actual uses in comparison with the conventional coated steel sheets which contain chromium.