Optimization of selective laser melting parameters and post-processing for enhanced mechanical properties of IN718 superalloy

Purpose The purpose of this study is to optimize selective laser melting (SLM) process parameters to fabricate Inconel 718 (IN718) components with minimal defects and enhanced mechanical properties. The combination of hot isostatic pressing (HIP) and solution treatment and aging (STA) post-processing was applied to reduce residual stresses, improve densification and minimize anisotropy. The goal was to identify parameter sets suitable for producing high-integrity components that meet stringent aerospace industry standards. Design/methodology/approach The influence of SLM parameters on IN718 was evaluated after HIP followed by STA. A modified Taguchi L9 orthogonal array was used to optimize process parameters for defect minimization. Nine build conditions were tested by varying laser power (300–400 W), scanning speed (520–1,400 mm/s), while keeping hatch distance (0.11 mm) and powder bed layer thickness (0.04 mm) constant. Optimal parameters were identified through experimental validation and subsequent mechanical and microstructural characterization. Findings The optimal SLM parameters were identified as 360 W laser power and 960 mm/s scanning speed, resulting in a relative density above 99%. In the HIP + STA condition, mechanical testing yielded an ultimate tensile strength of 1,437 ± 34 MPa, yield strength of 1,108 ± 181 MPa and elongation of 21 ± 3%. Microstructural analysis confirmed nearly full density, complete recrystallisation and absence of pores. This study demonstrated significant improvements in isotropy and densification for SLM-processed parts. Originality/value This work demonstrates the successful application of a modified Taguchi approach for optimizing SLM process parameters to produce high-density IN718 components. By incorporating HIP and STA treatments, this study effectively reduces anisotropy and internal defects, contributing valuable insights into the manufacture of reliable, defect-free parts for aerospace applications. The methodology and findings provide a robust pathway for achieving superior mechanical performance in additively manufactured superalloys.