Corrosion Resistance of Welded Joints of Austenitic Steel Microalloyed with Rare-Earth Metals

Abstract

We study the influence of rare-earth metals (REM) on the electrochemical and corrosion behavior of deposited austenitic metals in solutions of sulfuric acid. The corrosion resistances of 12Kh18N10T, 07Kh19N11M3, and 10Kh20N9G6T steels are measured by the electrochemical and gravimetric methods. It is shown that the corrosion resistance of the deposited metal in aggressive media can be made 2–4 times higher by introducing metallic yttrium, yttrium oxide, yttrium fluoride, or an yttrium–silicon hardener in the material of the electrode. It is demonstrated that the rate of corrosion processes noticeably decreases as a result of complex microalloying with yttrium and cerium up to their residual concentrations of 0.0019 and 0.0035 wt.%, respectively. The protective action of REM becomes more pronounced as temperature increases. It is also shown that REM modify the structure of the weld metal and promote the formation of protective passive films on the metal surface characterized by the elevated concentrations of yttrium, cerium, and chromium and suppressing the anodic and cathodic reactions. The proposed electrodes containing REM can be recommended for welding corrosion-resistant austenitic steels. The welds microalloyed with REM exhibit high corrosion resistance in aggressive media.