Process Optimization of Inconel 718 Alloy Produced by Laser Powder Bed Fusion

Abstract

To cut the cost of the laser powder bed fusion (LPBF) process, which is much higher than that of the traditional manufacturing process, an effective implementation of optimization analysis is needed. The study investigated the optimization of the LPBF Inconel 718 alloy with the Taguchi method and principal component analysis (PCA), covering four control factors at three levels in the manufacturing process. It focused on four mechanical properties, namely tensile strength, elongation, impact energy, and hardness. The results show that the highest tensile strength is obtainable at a laser power of 140 W, scanning speed of 800 mm/s, scanning pitch of 70 μm, and interlayer angle of 45 degrees. The optimal combination of process parameters for multiobjective optimization is just the same as that for single-objective optimization for tensile strength. The difference between the predicted and experimental average tensile strength is 1.2%, and the error of the predicted optimal strength index is 12.6%. The most important control factor for tensile strength and multiple responses is the angle between layers, with a contribution rate exceeding 90%. With a given volume energy density of the LPBF process, the higher the power and scanning speed, the higher the accumulated energy and the larger the amount of dendritic or cellular crystals formed.

Keywords

• additive manufacturing
• laser powder bed fusion
• Inconel 718
• optimization
• Taguchi method
• principal component analysis (PCA)