The galvanic corrosion behavior of Ni-Cr-Fe-P fillers and vacuum-brazed UNS S31803 duplex stainless steel (DSS) in a galvanic couple has been investigated. The Ni-Cr-Fe-P fillers were made from mechanical alloying iron and chromium into the BNi-7 filler in a mixer/miller for 3 h. By varying the amount of Fe and Cr powders added into the BNi-7 filler, the filler compositions were adapted to reduce the galvanic effects between the filler metal and the UNS S31803 DSS substrate. The galvanic corrosion behavior was studied using galvanic current measurements and weight-loss measurements. The experimental result showed that, coupled with Ni-22.4Cr-6.7P-20Fe filler, the UNS S31803 DSS brazed joint exhibited a very low nominal current density in a 3.5% sodium chloride (NaCl) solution. From the immersion test, it was also found that the brazed joint using Ni-22.4Cr-6.7P-20Fe filler had the lowest weight loss among all specimens. By adapting the filler composition to UNS S31803 DSS, the effect of galvanic corrosion on the vacuum-brazed joint could be substantially reduced and an increase in the vacuum-brazed joint shear strength was observed.
