Research Progress of Laser Additively Manufactured Inconel 718 Superalloy

Thanks to the excellent high-temperature mechanical properties and the good resistance to hot corrosion, Inconel 718 superalloy is widely used in aerospace, gas turbines, nuclear power and fossil fields. Recently, laser additive manufacturing (LAM) technique, with the characteristics of design freedom and near net shaping, shows great potential applications in the fabrication of complex and precise Inconel 718 components. Owing to the rapid heating and cooling process of LAM, the size of dendrite/cell and precipitates is much finer than that fabricated by traditional methods. Moreover, the resulted hierarchically heterogeneous microstructure shows unique correlation with mechanical properties. With extensive research on the LAM of Inconel 718 superalloy, the mechanical properties can reach or even exceed the as-forged counterparts. Ho-wever, significant solidification texture and large residual tensile stresses in the Inconel 718 superalloys fabricated by LAM give rise to anisotropic mechanical properties and poor fatigue durability, which limits LAM technique to a large certain extent. To this end, the application of LAM technology needs to start from the perspective of multi-scale microstructure, through processing control and post-processing treatment, to achieve high-quality the Inconel 718 superalloys fabricated by LAM. In this article, the research progress of laser selective melting and laser solid forming technology in the fabrication of Inconel 718 superalloy is summarized by focusing on the relationship of process parameters, microstructures and mechanical properties. The effect of LAM methods and processing parameters on the microstructures (such as dendrite growth, precipitates, grain structure and residual stresses) and the mechanical properties are highlighted. In addition, the solutions to the difficulties of the Inconel 718 superalloys fabricated by LAM are discussed. © 2022, Materials Review Magazine. All right reserved.