Marzieh Kishan Roodbari
Norwegian University of Science and Technology, Norway
Title: Effect of microstructure on the performance of corrosion resistant Al alloys
Biography
Biography: Marzieh Kishan Roodbari
Abstract
In this study, the corrosion behaviour of alloys was explored as a function of time using the salt. Samples from two aluminium alloys from series 5xxx and 6xxx were prepared and tested in a salt spray chamber in the duration of 49 days. At speciffed intervals, two samples of each alloy were taken out from the chamber. The type of corrosion and the corrosion rate were investigated through this test. As pitting is the main corrosion process, the depth of ten deepest pits was measured using optical microscopy. Also, the cross section of the deepest pit was analysed to see if the alloy is susceptible to intergranular corrosion. Statistical analysis was carried out in order to investigate the variation of corrosion rate during exposure and to predict the lifetime of a component. In particular, the Extreme Value theory, the Gumbel distribution, was employed to plot the probability paper of the extreme pit depth occurrence. In addition, the open circuit potential transient technique was utilized to investigate the corrosion potential of alloys under study. The ability of alloys to form the passive layer and the corrosion parameters such as corrosion potential were determined using potentiodynamic polarization measurement. The corrosion behaviour of alloys was found to be linked to the chemical composition and microstructure. The Gumbel extreme value distribution fitted successfully to the data obtained for alloys exposed to acidified seawater solution.