Design, processing, and assessment of additive manufacturing by laser powder bed fusion: A case study on INCONEL 718 alloy

During the designing stage of the laser powder bed fusion (LPBF) process for the production from a new material system, the operating variables form a large experimental parametric space. An efficient method to find the optimal parametric window of the variables is needed to enhance the essential advantage of the additive manufacturing technology - rapid prototyping. This article presents a simple analytical method to generate an optimal parametric window by estimating the melt pool dimension during the process of LPBF. By treating the well-studied INCONELTM 718 as a new system, the phase diagram, thermodynamic and thermophysical properties of the material were derived from the information available to the general public. Based on these data, a 4 x 4 parametric matrix was designed for a laser with focal diameter of 0.085 mm and 16 samples were built. The metallographic examinations of these as-built samples were performed to study the melt pool dimensions and microstructures of the samples. From the initial as-sessments on the structural quality of the as-built samples manufactured by the parametric matrix, it is proposed that the laser energy ranging from 45 mJ to 60 mJ, or the linear energy density from 0.53 J/mm to 0.71 J/mm, on an 85 mu m x 85 mu m area was the optimal operating window. From the study, it was concluded that the results of analytical calculations on the INCONELTM 718 material system agreed reasonably well with the experimental findings and the method can be applied to other new material systems to establish the optimal parametric window. Published by Elsevier B.V.