1979 Volume 48 Issue 7 Pages 510-515
The corrosion behaviour of silver brazed SUS 304 stainless steel has been studied in 0.4M NaCl solutions with additions of CuCl2⋅2H2O up to 0.05M. Effects of filler alloy composition and copper in solutions on the corrosion behaviour were discussed. Simultaneous corrosion of filler alloy and stainless steel at brazed interface took place. To evaluate each corrosion rate, a new specimen shape, filler alloy was flown along the stainless steel groove with the radius of 2.5 mm, was used. Major elements of filler alloys and stainless steel except silver were dissolved into the solution. The corrosion of filler alloy was the preferencial dissolution of α-Cu (mainly Cu-Zn) phase. Filler alloys containing cadmium and indium had lesser corrosion resistance than Ag-Cu-Zn ternary alloys and exhibited rapid interfacial corrosion.
Corrosion rates of filler alloys and interface were found to depend greatly on the copper content in chloride solution. Copper increased the corrosion rate mainly by the enhancement of cathodic reaction. Over the range of this study, BAg-4 filler alloy was suitable for the corrosion resistant SUS 304 braze joint.