Identification of Chromium-Depleted Area around Chromium Nitride Precipitates in Heat-affected Zone of Lean-Duplex Stainless Steel and In-situ Observation of Preferential Dissolution by EC-AFM

A Gleeble thermo-mechanical simulator was used to simulate the welds of duplex stainless steel S32101. A micro-precipitate of chromium-nitride and its surroundings in the simulated welds was analyzed in detail by SEM/AES and EC-AFM. The AES analysis revealed that a chromium-depleted area is present in the γ phase near the chromium-nitrides precipitated at the α/γ grain boundary. The EC-AFM observation revealed that the duplex stainless steel preferentially dissolves from the chromium-depleted area.