Optimization of the heat treatment strategy for Inconel 718 superalloy produced by laser powder bed fusion additive manufacturing process

This study investigates the impact of heat treatments on the microstructure and mechanical properties of Inconel 718 components fabricated by Laser Powder Bed Fusion (LPBF). To address residual stresses and microstructural inhomogeneities caused by rapid thermal cycles, three sequential treatments homogenization heat treatment (HHT), solution heat treatment (SHT), and aging heat treatment (AHT) were applied. Using a multi-objective Response Surface Method (RSM), heat treatment parameters were optimized. HHT was conducted at 1080 °C for 1–8 h, followed by SHT (980–1140 °C for 1 h) and standard AHT. Results revealed that a 2-h HHT led to optimal mechanical performance and a refined, uniform microstructure by redistributing Nb and Ti precipitates from the γ-matrix, enhancing the alloy's strength and service capability.