Discoloration resistance of architectural titanium sheets in long-term atmospheric exposure tests

The discoloration resistance of three types of titanium sheets-vacuum-annealed, pickled, and anodized gold-was evaluated by atmospheric exposure over several years in Okinawa and Kagoshema, Japan, and Beijing, China. Okinawa was the most severe site; of the sheets exposed there, those having low titanium cathide (TiC) precipitates had excellent resistance, those with high TiC precipitates had poor resistance, and the pickled sheets had a resistance level between the other two.