Effect of nickel on conductivity and corrosion of copper/stainless steel GTAW joints

According to the requirements of the new type copper/stainless steel electrolytic copper permanent cathode plate welding joint, T2 copper and 316L stainless steel were jointed with GTAW welding method. Three different Ni content welding wires S201, S231 and CuNi-7 were applied as filler materials. The microstructure, composition, electrical conductivity and corrosion resistance of joints were studied by optical microscope, scanning electron microscope, energy spectrometer, metal conductivity meter and electrochemical workstation. The results showed that no obvious defects are occurred in the interface of joint with three different wires. When the content of Ni is low, a small amount of microcracks generate in the steel side weld. The strip, block-like Ni-Cr-Fe phases increase with the increasing of Ni content. There exists an inverse relationship between the conductivity of joint and the amount of Ni-Cr-Fe phase. The corrosion resistance of joint under acidic condition can be greatly improved by the increasing content of Ni in the joint.