Abstract: Inconel 718 superalloy (IN718) fabricated by selective laser melting technology (SLM) has been successfully used to make some components with an excellent high-temperature performance. Microstructural evolution of SLM IN718 superalloy under the conditions of aging and different stressing conditions were investigated in this study. SEM, EDS and EBSD were employed to characterize the evolution of microstructure. This study shows that stress condition accelerates diffusional processes of alloying elements in the SLM IN718, which led to increase of grain size and coarsening of Laves phase and δ phase. EDS mapping shows that Ti rich Laves phases segregate along grain boundary, which induces initial cracks under stress condition. However, stresses have little effect on changing of grain boundary misorientation angle during a longtime aging treatment. Hardness of the SLM IN718 decreases with increase of aging time, mainly arising from increase of size and decrease of volume fraction of γ′′ and γ′ phases.
Authors: Zhen Xu, Chuan Guo, Zhenrong Yu, Xin Li, Xiaogang Hu, and Qiang Zhu
Keywords: Microstructure Evolution, Stress Conditions, IN718, Selective Laser Melting