Microstructural Investigation and Evaluation of Surface Properties and Hardness in Inconel ۷۱۸ Parts Fabricated by Selective Laser Melting (SLM) with Heat Treatment Application

Metal additive manufacturing, especially the Selective Laser Melting (SLM) method, enables the production of complex parts with controlled microstructure. The nickel-based superalloy IN۷۱۸, as one of the most widely used materials in high-temperature applications, is utilized in aerospace and energy industries due to its optimal combination of strength, corrosion resistance, and thermal stability. However, rapid thermal cycles and high temperature gradients in the Selective Laser Melting process can lead to the formation of heterogeneous microstructures, significant surface roughness, and local variations in mechanical properties. This research investigates the effect of post-manufacturing solution and aging heat treatment on the microstructure, as well as on surface roughness and hardness, of IN۷۱۸ parts produced by the Selective Laser Melting method. Samples were prepared in both as-built and heat-treated conditions and were evaluated using optical and scanning electron microscopy, surface roughness testing, and micro-Vickers hardness testing. Results showed that heat treatment leads to a more homogeneous microstructure, alleviates initial inhomogeneities, and improves the uniformity of phase distribution. Alongside these microstructural changes, surface roughness and hardness were evaluated in the as-built condition. Comparison of these properties in the as-built samples indicated a surface with relative roughness and initial hardness corresponding to the fabrication conditions. The present study emphasizes the effective role of heat treatment in optimizing the microstructural characteristics of SLM-produced IN۷۱۸ components and provides a basis for future integrated investigations.

کلیدواژه ها:

Additive Manufacturing ، Selective Laser Melting ، Inconel ۷۱۸ ، Microstructure ، Heat Treatment ، Solution and Aging ، Surface Roughness ، Hardness