Development of a Chromium-free Consumable for Austenitic Stainless Steels: Effect of Dilution and the Behavior of Bead-on-plate Welds

摘要

A Ni-10Cu-1Pd alloy was studied as a potential Cr-free consumable for welding austenitic stainless steels. The corrosion behavior of as-cast buttons with this base composition and alloys diluted by Type 304L stainless steel at levels of 4 to 84% were investigated in Cl~- solutions. Actual welds, made using a bead-on-plate welding technique, were evaluated using electrochemical testing and in long term crevice corrosion exposure testing. Ni-10Cu-1 Pd alloy across the entire dilution range exhibited higher repassivation potential than Type 304L stainless steel in 0.1 M NaCl solution. The repassivation potential was also higher for 0, 25, and 50% dilution levels in aerated solutions with Cl~- concentrations of 105-35 000 ppm. The breakdown behavior of the bead-on-plate welds was similar to that of conventional welds made with Type 308L filler metal. After 31 d exposure of samples with crevice-formers in 500 and 1 000 ppm Cl~- solutions, the bead-on-plate weld showed one shallow attack in 1 000 ppm Cl~-, but the 308L weld was attacked both in 500 and 1 000 ppm Cl~- with many deep pits.