Process Optimization of Duplex Stainless Steel Fabricated by Multi-Beam Laser Directed Energy Deposition

Multi-beam laser directed energy deposition (Multi-beam LDED) is an additive manufacturing process that employs multiple laser beams focused on melting and depositing metallic materials. This technology enables the fabrication or repair of duplex stainless steel (DSS) components. In this study, DSS cladding layers were fabricated via a multi-beam LDED system. Based on response surface methodology (RSM), a systematic investigation was conducted into the effects of three key process parameters—laser power, scanning speed, and wire feeding speed—on the width, W/H, and dilution rate of single-pass DSS cladding layers. Ultimately, through prediction and experimental validation, the optimal process parameters were determined as follows: total laser power (P_total) = 2241.6 W, scanning speed (V) = 7.91 mm/s, and wire feeding speed (R) = 1.27 cm/min. Under these optimal parameters, the single-pass DSS cladding layers exhibited a width (W) = 3.25 mm, a W/H = 2.3, and a dilution rate (η) = 36.27%. The deviations between the predicted and validated values were all below 5%. Furthermore, microstructural characterization and microhardness distribution analysis were performed. The results indicated that the cladding layers were composed entirely of austenite and ferrite phases, with no impurity phases detected. EBSD analysis revealed the presence of abundant grain dislocations within the cladding layers, which contributed to an average microhardness of 350 HV.