Effect of metallurgical factors on initiation of pitting corrosion on aluminum in fresh water

Various metallurgical factors governing initiation of pitting corrosion were examined by electron microscopy, EPMA, and cathodic polarization measurements. Pits nucleate in the adjacent site of precipitates containing iron and/or silicon. Pits are prone to initiate on the cutting edge rather than on rolled surface of aluminium plate. Scratching has the most remarkable effect on initiation of pitting corrosion. The difference in susceptibility to pitting corrosion between the edge and the rolled surface of aluminum plate is attributed to the scratching effect on the edge surface.