tailieunhanh - Handbook of Corrosion Engineering Episode 1 Part 15

Tham khảo tài liệu 'handbook of corrosion engineering episode 1 part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Acceleration and Amplification of Corrosion Damage 511 surfaces with optical and scanning electron microscopy suggested that the correlation between the CPE and the pitting rate involved the number of pits formed in any given area pit density rather than the pit depth. The low pitting rate suggested by EIS for the rolled surface was consistent with visual observation of the long-term-exposure panels. However the approximate equivalence for all three faces was not. If the interpretation of EIS data is correct the corrosion of the rolled surface must occur initially at this high rate. However the corrosion rate would then fall to a much lower value over the longer term. The Rp values for the 2024-T3 alloy showed a pronounced difference in overall corrosion rate between the rolled surface and the edges with the edges having consistently higher rates. After about 50 h a similar trend was observed for the CPE. These results were consistent with observations made on the long-term-exposure panels which were characterized by a higher density of localized corrosion sites on the On the basis of the EIS data the conclusion would be reached that the edges of the 8090-T8 alloy had lower overall corrosion rates and were less prone to pitting than their 2024-T3 counterparts. The edges of the 8090 long-term-exposure panels had substantial areas where no visible corrosion had occurred. This could be consistent with the lower overall corrosion rates and lower pitting density in comparison with the 2024. However the depth of attack within each pit Fig. was as large as or larger than that of a corresponding pit on 2024. Thus the rate of corrosion within a pit was at least as severe for 8090 as for 2024. As was the case for the 8090 alloy the corrosion rate determined with EIS for the rolled surface of the 7075 was approximately equal to that measured for the edges. This was not consistent with the appearance of the long-term panels which suffered more metal loss along .