Atmospheric Corrosion of 904L Austenitic Stainless Steel at Different Environments

Thursday, 5 October 2017: 11:40
Camellia 2 (Gaylord National Resort and Convention Center)
A. M. Abdullah (Qatar University), M. H. Sliem (Center for Advanced Materials, Qatar University, Qatar), and A. M. Mohamed (Suez Canal University)
A major concern for metals and alloys in structural applications is susceptibility to atmospheric corrosion. The atmospheric corrosion behavior of 5 mm-thick 904L austenitic stainless steel (904L SS) coupons of dimensions 10 x 10 cm2 was studied as a part of a field exposure program for many alloys under a variety of environmental conditions that are existing in Qatar. Seven locations (stations) were selected to participate in this study representing desert, marine, coastal and industrial areas in Qatar. The study was implemented using image analyzer, scanning electron microscope (SEM) coupled with energy dispersive x-ray (EDAX) and electrochemical characterization techniques. The number of pits and pits’ depths and aspect ratios were calculated. Moreover, the thickness of oxide layer was detected using x-ray photoelectron spectroscopy (XPS). The analysis of the collected coupons revealed the corrosion behavior of 904L SS specimens and fasteners in various exposure conditions after different times of exposure. In addition, a correlation was made between the effects of various environmental conditions e.g. Cl-, and SO2 concentration in air and the extent and forms of corrosion. In general, 904L SS alloy formed several pits in the crevice regions and some pits also appeared on its flat surface, especially at marine and coastal industrial sites. Test coupons at desert test station didn’t form any corrosion products on its surface or around the crevice areas. It is clear that the number, the size and the aspect ratios of pits depend on the aggressiveness of the site’s environment. The pits’ density and aspect ratio were found to follow the following order; North field > Ras Laffan > Seaside Mesaieed > Industrial Mesaieed > Halul > Dukhan > Desert.