Luu, D. N., Huang, J., Liew, Y., Nathaniels, A., Goh, J. Y. J., & Ten, J. J. S. (2026). Tailoring mechanical properties and corrosion resistance via recrystallization-induced microstructural control in LPBF-fabricated IN718. Materials & Design, 262, 115426. https://doi.org/10.1016/j.matdes.2025.115426
Abstract:
This work establishes a grain boundary engineering strategy for laser powder bed fused Inconel 718 by exploiting recrystallization-induced microstructural co-evolution. Columnar as-built and recrystallized twin-rich equiaxed microstructures are generated from a single LPBF build through tailored solution treatment, enabling a controlled comparison of grain morphology, Σ3 twin fraction, dislocation density, and Laves/δ phase segregation. The equiaxed condition, with isotropic ∼56.5 µm grains and 63.8% Σ3 boundaries, shows strongly reduced geometrically necessary dislocation density and Laves phase content relative to the columnar condition with ∼17.4 µm elongated grains. Furthermore, only nano-sized precipitates occur at twin boundaries, while the general high-angle grain boundaries are enriched in large Laves phases. This microstructural combination delivers favourable balanced properties, with only 6.8% loss in yield strength but greater strain hardening and 25.1% enhanced elongation at room temperature. Similar trends observed at 650 °C underscore the continued influence of initial microstructures. In aggressive boiling oxidizing solutions, the equiaxed microstructure forms significantly fewer Nb/Mo-rich scales and exhibits a ∼33% lower corrosion rate (39.24 vs 52.21 g/m2·h). The results show that recrystallization-driven twin network formation and Laves depletion provide an effective route to optimize mechanical performance and corrosion resistance in LPBF-fabricated IN718 simultaneously.
License type:
Attribution 4.0 International (CC BY 4.0)
Funding Info:
This research / project is supported by the A*STAR - Manufacturing, Trade and Connectivity (MTC) Industry Alignment Fund-Pre-positioning (IAF-PP) Grant: Metal AM Powders: Reusability, Rejuvenation, Cost, Quality & Performance (RRAMP)
Grant Reference no. : M22K7a0047
This research / project is supported by the RIE2025 2nd CSIRO and A*STAR: Research-Industry (2+2) Partnership Program - Advancing Metal Matrix Composites for Additive Manufacturing Industrial Applications using Next-Generation Hybrid Powders Prepared by Impact Blending and Ordinarily Mechanical Blending
Grant Reference no. : R24I3IR048