Influence of Specimen Area on the Pitting Probability of Aluminum

Abstract

The pitting probability of 2S aluminum was determined in Kingston tap water as a function of area, for areas ranging in size from 0.06 cm 2 to 243 cmt The pitting probability was found to vary uniformly with area, from 0.001 to 1 as the area increased from 0.06 cm 2 to 60 cm~; extrapolation indicated that the pitting probability becomes zero at an exposed area of about 0.055 cm ~. This work supports the contention that pitting sites in aluminum are not specific macrodefects in the metal surface, but rather arise in a random fashion through the interaction of myriads of anodic and cathodic elements on the metal surface.