Optimising the Phase Distribution in Arc-Based Direct Energy Deposition of Duplex Stainless Steel

Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW) arc-based Direct Energy Deposition (DED) techniques were employed to generate type 2209 duplex stainless steel builds. Different deposition parameters were applied to determine the effect of interpass temperature and heat input on the resulting austenite-ferrite phase fraction. Macro and micro-structure characterisations were carried out using optical microscopy, Energy Dispersive X-ray spectroscopy (EDX), wavelength dispersive spectroscopy (WDS) mapping and Electron Backscattered Diffraction (EBSD) analysis. ThermoCalc simulations were compared to thermal measurement during manufacturing, and a correlation between interpass temperature and the measured austenite fraction was obtained. This study supports the possibility of achieving a homogenous phase fraction across 70% of the building direction without the requirement of post-deposition heat treatment processes. Further analysis confirmed phase balance homogeneity across the welding pass, even upon producing a larger component.