Sensitivity of Aluminium Alloys to Pitting Corrosion

AU aluminium alloys are prone to pitting corrosion in natural environments. Experience shows that the resistance to pitting corrosion is higher if the density of initiated pits is high. 

For thin products with a thickness below 100 fim, the pitting depth can be limited by adding up to 1% iron to the aluminium (alloys 801 lA and 8079). The increase in the number of cathodic AlaFe intermetallics increases the number of initiated pits. 

For the same reasons, a small amount of copper (0.10-0.20%) is added to alloy 3003, in order to multiply the initiation sites of pits on AI2CU intermetallics. 

The pitting corrosion rate and the pitting depth are independent of metal thickness [13]. 

Within the metal, at the level of the grain, corrosion may propagate in two different ways  

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Sensitivity of Aluminium Alloys to Pitting Corrosion Transgranular and Intergranular (Intercrystalline) Corrosion... 

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