Study on Grindability of Inconel 718 Superalloy Fabricated by Selective Laser Melting (SLM)

The selective laser melting (SLM) process is widely used to fabricate parts with sophisticated geometry. The microstructure and mechanical property of SLM Inconel 718 alloy show anisotropy. However, the influence of anisotropic microstructures on the grinding process and surface integrity is not yet clear. In this article, a grinding experiment with a corundum wheel is performed. Before the experiment, the microstructure for both the scanning plane and the side plane is observed to disclose the microstructural anisotropy During the experiment, the grinding power signal is measured to represent the time-dependent performance. After the experiment, the surface roughness is measured to represent the surface quality. In addition, microhardness is measured to determine the influence of the anisotropic microstructure on the grind ability. Experimental results indicate that the scanning plane consists of many strip structures along the scanning direction while the side plane is characterized by scaly structures and layered structures. Moreover, because of the layered structures, the microhardness profile along the Pudding direction varies more in comparison to the scanning direction. Furthermore, better surface homogeneity and smaller roughness fluctuation can be obtained along scanning feed direction in comparison to the building feed direction. Additionally, microstructures will influence its hardness, which will further influence the grinding power. Therefore, the grindability of SLM Inconel 718 exhibits anisotropy because of anisotropic microstructures.