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Duplex stainless steels are widely used in industry. This is due to their higher strength compared to austenitic steels and to their higher toughness than ferritic steels. They also have good weldability and high resistance to stress corrosion cracking. These steels are characterized by two-phase microstructures composed by almost the same level of ferrite and austenite. Duplex steel 2205 samples evaluated are: as received, cold rolled (33%) and heat-treated at 800°C for 10 hours. A metallographic etching with 10% oxalic acid has been carried out to highlight the phases morphology. Some photos have been taken by SEM microscope and submitted to image analysis. The analysis carried out is based on the determination of co-occurrence matrix and on the following interpretation of appropriate indicators. Through these indicators is possible to estimate the features of images objectively.

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Adding titanium to a hot-dip galvanising bath, a coloured oxide film due to interference effect was obtained on iron samples; different colours were achieved varying the bath temperature in the range of 520-600°C. In this paper, the resistance of three colours (yellow, purple and light blue) to four corrosive environments (urban, marine, industrial and rural) has been investigated by means of an experimental approach: two specimens of each colour with titanium percentage of 0.2% were exposed for 1 year in each environment and colour measurements in CIE Lab coordinates have been recorded at fixed time intervals. Modification of colours on samples due to corrosion effects of different chemical agents was evaluated calculating CIE colour difference. Results demonstrated that the colour of the coatings have a good resistance to all kinds of atmospheres tested; so the performance of this galvanising bath resulted adequate for architectural application.