Abstract
In recent years, aluminum alloys are attracting attention as materials for high-efficiency and eco-friendly ship. The aluminum ship can operate at high speed with low fuel consumption due to its light weight. Moreover, because of its low the melting point when scrapping a ship it is easy to recycle. However, as the ship speed increases, the cavitation erosion damage also increases because the fluid impact on the hull increases. Corrosion damage is also accompanied by the harsh marine environment. Hence, the case of hull damage is increasing due to the synergistic effect of corrosion and cavitation erosion.
In this investigation, corrosion resistance and durability of three different Al alloys (5052-O, 5083-H321, and 6061-T6) for marine environment. Various electrochemical polarization experiments were carried out to evaluate the corrosion resistance of aluminum alloys. And then, the corrosion damage tendency of each material was compared through the polarization curve, 3D microscope and SEM analysis. On the other hand, the cavitation-erosion experiment was conducted to evaluate the durability of the aluminum alloys. These experiments were carried out at 5 ㎛, 10 ㎛, and 30 ㎛ amplitude for detailed comparative evaluation of surface damage characteristics. In addition, cavitation erosion damage tendency of each material were compared through weight loss, damage depth and the surface morphologies by 3D microscopy and SEM analysis.
As a result, the 6061-T6 alloy was the most excellent in the corrosion resistance and was poorly evaluated in the order of 5052-O and 5083-H321 alloy. However, the 6061-T6 alloy is not suitable as a material for marine or offshore structures because of the local corrosion tendency. The cavitation erosion resistance results presented that 5083-H321 alloy was the most excellent and was poor in the order of 6061-T6 and 5052-O alloy. Consequently, the comprehensive comparison of electrochemical corrosion and cavitation erosion characteristics indicated that 5083-H321 alloy was the most suitable material for the ship.