激光粉末床熔融成形 IN718 高温合金薄壁组织、缺陷及力学性能研究进展

IN718 superalloy is extensively utilized in the aerospace and nuclear industries due to its outstanding oxidation resistance, heat-corrosion resistance, good structural stability, fatigue performance and safety reliability. It is one of irreplaceable materials for the hot-end components of next-generation advanced aircraft engines. Recently, laser powder bed fusion (LPBF) technology has developed as an innovative rapid prototyping technique, transcending the limitations of traditional shaping methods and structural designs. This technology has realized one-step laser near-net shaping of complex thin-walled structures, demonstrating substantial application potential. However, during the laser additive manufacturing process, the thin-walled surfaces are exposed to high laser input energy, which can readily induce warping, deformation, and even cracking, significantly impacting the service performance of these structures. To address these challenges, this work provides an overview of the working principle and recent advancements in LPBF technologies. It systematically analyses the multi-scale microstructural evolution and precipitation phase behavior of IN718 superalloy thin wall fabricated by LPBF. Special emphasis is placed on the initiation, propagation mechanisms and mitigation strategies for metallurgical defects, including optimized thin-walled structural designs, laser forming process parameters and alloy composition. In addition, the strengthening mechanisms underlying the mechanical properties of IN718 superalloy thin wall at both room and high temperatures are analyzed and discussed. Finally, the work summarizes the existing challenges such as insufficient critical performance under harsh conditions and future development directions of superalloy thin wall fabricated by LPBF, including establishment of laser forming process databases specialized for superalloy thin wall, investigation of solidification defect formation and novel control strategies in superalloy thin wall fabricated by LPBF, and optimization of the chemical composition design for high-performance superalloy thin-walled components.