Characterization of Functionally Graded Material (Stainless Steel 347/308L) Fabricated through Wire and Arc Additive Manufacturing: Microstructure and Mechanical Perspectives

This study investigates the fabrication and mechanical assessment of functionally graded material (FGM) walls using metal inert welding‐based wire and arc additive manufacturing (WAAM) technology. The research utilizes stainless steel (SS) 308L and SS 347 filler wires to create FGM, which offers a smooth gradient of diverse material properties, enhancing its functional versatility. The FGM, made from a combination of 308L and 347 filler wires, exhibits superior mechanical attributes, including a tensile strength (TS) of 632.1 ± 6.1 MPa, making it a preferred choice for application prioritizing mechanical performance. Compared to WAAM‐processed SS 347 (TS: 559.4 ± 7.6), FGM consistently shows improved TS and retains ductility. Additionally, FGM displays a hardness of 239 HV, which is higher than the average hardness of SS 347 (226.2 HV). This improvement is attributed to microstructural changes influenced by cyclic thermal history, resulting in inhibited grain growth and formation of a dendritic structure and residual ferrite in WAAM‐processed FGM. The ferrite number in interface is measured to be 5.3. The study underscores the potential of FGM (SS 308L/SS 347) in fulfilling the requirements of engineering application such as pipelines, pressure vessels, and power plants, which demand superior mechanical properties. The aim of this study is to provide firsthand knowledge on the fabrication of functionally graded material (FGM) (SS 347/SS 308L) through metal inert gas welding‐based wire arc additive manufacturing. FGM exhibits better mechanical strength than its respective wrought alloy; also, the microstructural variation favors its use in pressure vessels and piping application.