Statistical Analysis of the Optical Interferometry of Pitting Process in Aluminum 3003 Sheets Exposed to Saline Environment

摘要

In this study, a statistical evaluation was made of the susceptibility to pitting corrosion, using the pitting factor criteria. Specimens were cut in size of 15 cm x 10 cm of AA3003 aluminium sheet of temper H14, H16 and H18 of national production. Afterwards, they were exposed to a salt spray during 72, 144, 216, 288 and 360 hours continually, according to ASTM B117 standard. After salt spray test was observed pitting attack in all specimens regardless of the exposure time and the degree of deformation (temper) of material. The surfaces of the corroded specimens were analyzed by optical interferometry. The parameters evaluated in each field were: roughness (Rms), peak-valley distance (PV) and the lowest point of all peaks (V). A pitting factor of the order of 4 was calculated, indicating a highly localized corrosion process for this commercial aluminium alloy 3003 in saline environment.