Effect of Small Amount of Bismuth on Corrosion Resistibility of Austenitic Stainless Steel Weld Metals

Flux-cored are welding (FCAW) has increased recently because of high welding efficiency. However, a small amount of bismuth in the weld metals was a residue from the flux component that was added for improving slag detachability. The effect of small amount of bismuth in austenitic stainless steel weld metal on corrosion behavior in wet corrosion environment is not adequately clear because there is little reported to date. In the present research, the effect of bismuth which remained in the weld metal on the corrosion behavior of 308-type weld metal in wet corrosive solution was examined by using different bismuth containing weld metal. Measurement of the anodic polarization curve in a sulfuric acid solution, determination of pitting potential and conducting stress corrosion cracking (SCC) tests in a chloride solution, and implementation of boiling nitric add solution tests were conducted. In addition, the corrosion behavior of the FCAW weld metal was compared with that of Bi-free weld metals by shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) to clarify how the corrosion behavior varies between the welding processes. In this research, no noticeable adverse effect of bismuth remained in the 308-type austenitic FCAW weld metals was observed in corrosion test.