Enhancing duplex stainless steel additive manufacturing with DED-LB/w: microstructural analysis and process optimization

Abstract The applicability of additive manufacturing (AM) of duplex stainless steels has been limited by the complex thermal history causing an imbalance of ferrite and austenite in the as-deposited material. Laser-beam directed energy deposition with wire (DED-LB/w) presents a promising solution when combined with solution annealing. This study utilizes a specially developed 3Dprint AM 2205 and a conventional ER2209 wire to continuously build cylindrical components. Metallographic examination was conducted using light optical microscopy (LOM), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and electron microprobe analysis (EPMA). While high deposition rates were achievable, excessively high wire feeding rates led to continuous areas of fine grains in the deposited beads. These regions, identified as partially molten wire, were sometimes associated with lack-of-fusion, porosity, and solidification cracking. Optimized parameter settings enabled efficient melting of the wire, producing defect-free deposits, and eliminating partially molten wire residues. Solution annealing effectively dissolved intermetallics and homogenized the microstructure, resulting in a more uniform phase distribution.