Communication—Restoring the Pitting Resistance of Sensitized Duplex Stainless Steel Using Interstitial Hardening

Abstract

Cast duplex stainless steel, alloy 2205, a mix of ferrite and austenite, was heat-treated at 845 degrees C which produced additional phases, e.g., sigma and chi. The new phases depleted the surrounding grains of passivity-promoting elements such as Cr, causing alloy sensitization and a corresponding decrease in pitting resistance. A low temperature gas-phase interstitial hardening (IH) surface modification process was used to surface alloy sensitized samples. Anodic polarization curves showed that after IH treatment, the pitting resistance, determined by the pitting potential, of sensitized samples was restored to values of the as-cast material. (C) The Author(s) 2016. Published by ECS.