Effects of exposed area on corrosion behavior of high strength aluminum alloys in salt water

The corrosion characteristics of high strength aluminum alloys(2A12 and 7B04) with different exposed areas by 3. 5% (mass fraction) NaCl salt water immersion test were investigated. The corrosion damage ratio was calculated through the binary image that obtained from image processing. The results indicate that the size of exposed area of the specimens can affect the pit corrosion of both 2A12 and 7B04 aluminum alloys in salt water immersion condition. No obvious pitting characteristic can be observed when the exposed area is smaller than a certain value, which is termed as the critical area of pitting corrosion. The pitting corrosion damage ratio improves with increase of exposed area. In addition, the difference of the critical areas between 2A12 and 7B04 aluminum alloys shows that the components of the aluminum alloys can affect the critical value.