Microstructure and Microhardness Evolution of Additively Manufactured Cellular Inconel 718 after Heat Treatment with Different Aging Times

Abstract

The manufacture of cellular structures using high-performance materials is possible thanks to the additive manufacturing of metals. However, it is well known that the mechanical and microstructural properties of metals manufactured by this technique do not correspond to those of the same metals manufactured by conventional methods. It is well known that the mechanical properties depend on the direction of manufacture, the size of the pieces, and the type of cell structure used. In addition, the effect of heat treatments on parts manufactured by additive manufacturing differs from parts manufactured by conventional methods. In this work, the microstructure and microhardness of cellular structures of Inconel 718, manufactured by additive manufacturing under heat treatments with different aging times, were evaluated. It was found that the time of the first aging impacts the microhardness and its homogeneity, affecting the microstructure. The highest hardness was obtained for an aging time of 8 h, while the lowest standard deviation was obtained at 10 h. Finally, it is shown that the aging time influences a more homogeneous distribution of the elements and phases.

Keywords

• additive manufacturing
• Inconel 718
• heat treatment
• cellular structures
• metamaterials