Application of Corrosion Test Methods for Microstructure Screening of WAAM Duplex Stainless Steel

Duplex stainless-steel type 2209 has been subjected to Wire + Arc Additive Manufacturing (WAAM) with varying heat input and interpass temperatures. This creates a non-equilibrium microstructure that negatively impacts corrosion resistance. Various electrochemical techniques have been applied to link microstructure to pitting corrosion resistance, particularly examining the austenite phase fraction and elemental content distribution in the obtained austenite and ferrite. It will be demonstrated that reducing heat input from 1.15 kJ/mm to 0.54 kJ/mm and lowering interpass temperature from 250°C to 150°C mitigates the formation of deleterious acicular austenite and significantly enhances pitting corrosion resistance, evidenced by higher critical pitting temperature and pit initiation potential. Locations closer to the arc-start and arc-termination points exhibited lower pitting resistance, underscoring the significant influence of deposition direction on microstructure heterogeneity and resulting corrosion resistance.