Integrated Assessment of Mechanical and Electrochemical Properties of Additively Manufactured IN 718 Alloy Using Taguchi and Super Ranking Approaches

Abstract

The increased adoption of IN 718 alloy in marine and aerospace applications faces critical challenges due to aggressive chloride-induced degradation, making understanding its corrosion resistance imperative. Evaluating its mechanical performance (micro-hardness: MH and ultimate tensile strength: UTS) is equally essential and represents a critical area of study. The mechanical performance of IN 718 alloy is reliant on four influencing variables (laser power, scan speed, laser beam spot size, and layer thickness) of the selective laser melting (SLM) technique. The Taguchi L₉ matrix is designed to study and analyze the parameters and optimize the responses. Laser power showed a dominant impact on the mechanical performance of printed parts. Taguchi determined that optimal conditions were found to be different for both UTS and MH. The super ranking method determined that optimized SLM conditions resulted in MH and UTS values of 344.8 HV and 1051.2 MPa, as experimentally determined. Microstructural characterization was performed on IN 718 alloy powder, and fracture morphology was conducted at different parametric conditions. The corrosion behavior of optimized SLM-processed IN 718 alloy was evaluated in 0.1 M H₂SO₄ with varying NaCl concentrations (0.1–0.7 M) using potentiodynamic polarization and electrochemical impedance at room temperature. The addition of 0.7 M NaCl to 0.1 M H₂SO₄ provided the highest inhibition activity for IN 718 alloy, indicating that printed optimized parts can enhance its corrosion resistance in acidic environments.