| Abstract Scope |
Wire Arc Additive Manufacturing (WAAM) is a highly effective technique for manufacturing medium-to-large-scale components, providing high deposition rates, low-cost equipment, and exceptional material utilization. Nonetheless, its broader implementation in critical industrial sectors faces limitations due to anisotropic mechanical properties. To overcome these constraints, this study combines WAAM with in situ hot forging (HF) between deposited layers to refine the grain structure and improve mechanical performance. Specifically, WAAM was performed on 316L stainless steel using Gas Metal Arc Welding (GMAW) in conjunction with a robotic hammering mechanism for real-time hot forging. Layers were deposited onto a rotating substrate utilizing 316L filler wire (1.2 mm diameter) and a shielding gas mixture (98% argon, 2% CO₂) at wire feed rates of 3, 5, and 7 m/min. High-speed imaging and electrical signal monitoring were employed to assess molten pool behavior, while thermal simulations established optimal forging temperatures ranging from 950°C to 1150°C. Finite Element Method (FEM) modeling guided the strategic positioning of the hammering tool for optimal microstructural refinement. Results indicated improved process stability, prolonged short-circuit intervals, and enhanced deposit geometry attributed to the hot forging step. Metallographic examinations and Electron Backscatter Diffraction (EBSD) analyses demonstrated considerable grain refinement, showing larger equiaxed grain fractions compared to conventional WAAM. Microhardness mapping confirmed that dynamic recrystallization effectively increased hardness substantially. Additionally, instrumented tensile testing of both forged WAAM deposits and hot-forged reference samples highlighted significant improvements in mechanical properties due to refined microstructures. This investigation illustrates that integrating hot forging into the WAAM process is an innovative and practical approach to achieving superior mechanical and microstructural properties in additive-manufactured 316L stainless steel components, promoting their applicability in advanced industrial scenarios. |