Abstract
The mechanism of localized corrosion behavior for aluminum vacuum brazing T-joints has been investigated by means of a potentiostat etc. Specimens were prepared from brazing sheet which was made of A3003 (core) and Al-6.6%Si-1.97%Mg-0.18%Fe alloy (filler metal), and A1100 (base metal). The measurement of corrosion potentials and polarization curves were carried out for three positions on specimen. It has been found that base metal is less noble than filler metal, and the limiting diffusion current of dissolved oxygen for position 2, interface of base metal and filler metal, is the largest. From the result of surface observation by using scanning electron microscopy and electron probe micro analyser, it has been found that iron and silicon segrigate on the filler metal side of the interface. The result of dipping test showed that pitting corrosion occured at the interface of base metal and filler metal. Pitting corrosion of the aluminum vacuum brazing T-joints results from galvanic corrosion of base metal and segrigated iron on the filler metal.
