Effect of Welding Heat Input on Corrosion Behavior of Duplex Stainless Steel Welding Overlay on Carbon Steel

The present study investigates the effect of welding heat input on the corrosion resistance of duplex stainless steel (DSS) overlays, with particular focus on applications in pressure vessels and clad plates. ER2209 filler metal was deposited onto SA-516 Gr. 70 carbon steel using GMAW, both manually and mechanized, with varying heat inputs. Microstructural characterization included ferrite-content measurement, macrographic analysis, and pitting-corrosion testing according to ASTM G48 Method A. The results indicate that increasing the heat input from 548 J mm−1 to 2319 J mm−1 significantly reduced the ferrite content from 49% to 25%, leading to a corresponding increase in weight loss from 0.55% to 2.5%. Mechanized welding exhibited better arc stability and more consistent phase distribution compared to the manual process. Although we did not detect brittle phases or intermetallic precipitates due to strict interpass temperature control, the microstructural imbalance induced by high-heat-input directly compromised the corrosion resistance. These findings advance understanding of the optimized welding parameters required to ensure the integrity of DSS coatings in aggressive environments.