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Analiza wad powierzchniowych na anodowanych profilach aluminiowych ze stopu 6xxx

Boczkal S., Motyka M., Oprychał M.

Rudy i Metale Nieżelazne

2010

R. 55, nr 9

627-631

W artykule omówiono problematykę związaną z wadami powierzchni profili aluminiowych zarówno przed, jak i po procesie anodowania. Szczególnie zwrócono uwagę na jakość powierzchni przed procesem anodowania, gdyż wystąpienie wżerów korozyjnych na powierzchni profilu, zwłaszcza kiedy jest on stosowany jako element konstrukcyjny pracujący w zewnętrznych warunkach atmosferycznych, może doprowadzić do postępu korozji. Wszystkie wady powierzchniowe na profilu mogą również prowadzić do zmniejszenia walorów estetycznych gotowego wyrobu.

In this paper the problems connected with the surface defects of aluminium profiles before and after anodizing process are presented. Particularly the quality of surface of profiles before anodizing was discussed because occurrence of pitting corrosion on the profile surface may lead to the progression of corrosion, especially when it is used as the construction element working on the external weather conditions. All surface defects on the profile may also cause reduction in the attractive design of the final products.

Corrosion resistance of high-manganese austenitic steels

Grajcar A., Kołodziej S., Krukiewicz W.

Archives of Materials Science and Engineering

2010

Vol. 41, nr 2

77-84

Purpose: The aim of the paper is to compare the corrosion resistance of two new-developed high-manganese austenitic steels in 1N H2SO4 and 3.5% NaCl solutions. Design/methodology/approach: The steels used for the investigation were thermo-mechanically rolled and then solution heat-treated from a temperature of 850°C. Corrosion resistance of investigated steels was examined using the immersion test. The specimens were weighed and dipped in the prepared solutions for 100 h. After the test, the percentage weight loss was calculated. The metallographic investigations of corrosion damages included light and scanning electron microscope observations both in the polished and etched states. Findings: It was found that after the thermo-mechanical processing one steel is characterized by an austenitic structure with numerous annealing twins, whereas in the second steel ε and α' martensite plates in an austenitic matrix were observed. According to the results of the immersion tests it was found that the examined steels exhibit a comparable corrosion resistance. They show very poor corrosion resistance in H2SO4 solution and low corrosion resistance in NaCl medium. The weight loss in chloride solution is much lower, what is explained by different corrosion mechanisms. In both the solutions, the intensive general corrosion and corrosion pitting were observed. In acidic medium they are created in a way of hydrogen depolarization and in NaCl in the way of oxygen depolarization. Research limitations/implications: To investigate in more detail the corrosion behaviour of high-manganese austenitic steels, the investigations should include polarization tests and an analysis of corrosion products. Practical implications: The obtained results can be used to search for the appropriate way of improving the corrosion resistance of high-manganese steels with a single-phase austenitic structure as well as the austenite structure containing ε and α' martensite. Originality/value: The corrosion resistance of two types of advanced high-strength high-manganese austenitic steels with different initial structures was compared in acidic and chloride solutions.