Multi-scale Optimization and Computational Validation for Enhancing the Microstructure, Mechanical Properties, and Physical Performance of Wire Arc Additive Manufacturing-Fabricated SS309L Stainless Steel

SS309L stainless steel is commonly used in industries such as aerospace, marine, and energy due to its
excellent resistance to high temperatures and corrosion, as well as its superior mechanical strength. This
makes it an ideal candidate for fabrication using wire arc additive manufacturing (WAAM), a technology
known for its high deposition rates and cost-effectiveness. However, optimizing process parameters is
essential to enhance the mechanical properties, microstructure, and physical characteristics of SS309L
when fabricated via WAAM. In this study, response surface methodology (RSM) was applied to optimize
bead width and bead height in WAAM-fabricated SS309L. The optimization was conducted by varying
welding current (100-150 A), voltage (10-20 V), and travel speed (0.1-0.3 m/min). A multi-layered wall was
constructed using the optimized parameters (135 A, 16 V, and 0.1 m/min) for subsequent analysis of
mechanical properties and microstructure, as well as physical examination and finite element analysis
(FEA). The mechanical tests showed that the top section of the fabricated wall achieved an ultimate tensile
strength (UTS) of 561.81 MPa, a yield strength of 435.63 MPa, and an elongation rate of 41.2%. The
bottom section showed a UTS of 469.73 MPa with 45.6% elongation. The middle section exhibited a
maximum compressive strength of 984.2 MPa. Microstructural analysis using x-ray diffraction (XRD),
electron backscatter diffraction (EBSD), and scanning electron microscopy (SEM) confirmed that the top
section contained fine-grained structures, while the bottom section exhibited coarser features. The porosity
of the material was exceptionally low at 0.0081%. FEA simulations confirmed the experimental results,
validating stress and deformation patterns. The study provides a comprehensive methodology for optimizing SS309L WAAM structures for high-performance industrial applications