Corrosion of X2CrNiMoSi18-5-3 duplex stainless steel
2016
Lipinski, T., University of Warmia and Mazury in Olsztyn (Poland)
Duplex stainless steels offer economical properties of strength and corrosion resistance. There are ferritic-austenitic stainless steels popular as construction materials used in industrial applications. The fraction of each phase is approximately 50 %. These steels present excellent corrosion resistance of austenite steel, and high mechanical behaviour of ferrite steel. General important corrosion problems in duplex stainless steels at 475 ºC have already been detected. Although the worst temperature is 475 ºC, corrosion can still form at temperatures lower or higher. The corrosion resistance depends on increasing the chromium content and morphology of the microstructure, the percentage of each phase, so the properties depend on the composition, technological processes and heat treatments. However, the performance presented by duplex stainless steels can be drastically reduced if undesirable phases, such as the sigma phase, chi phase, secondary austenite and a lot of rich chromium and carbides precipitates. The purpose of this work was to ascertain how 30-minutes isothermal heat treatments at 530 ºC and corrosion time affect the relative mass loss and profile roughness parameters of X2CrNiMoSi18-5-3 duplex stainless steel. The influence of boiling nitric acid on the steel corrosion resistance was investigated using weight loss and profile roughness parameters.
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