Parametric studies on process parameters of directed energy deposition

• Main Author: Huang, Runcheng
• Other Authors: Wong Chee How
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/75092
• Institution: Nanyang Technological University

Additive manufacturing (AM) has attracted much research interest in recent years due to its ability to directly create complex geometries with customizable material properties from 3D CAD model without any tools and molds. AM has been classified into numerous terminologies: liquid-based such as inkjet printing, solid-based such as fused deposition modeling (FDM) and powder-based such as selective laser melting (SLM). Moreover, directed energy deposition (DED) is a one of the uprising powder-based AM technology because of its ability to build full-density and high-performance metal parts. DED technology would be the focus of this project. The process of DED involves depositing metal powder to the melt pool created by laser energy to generate continuous layer upon layer. It is well known for its application in repairing high-value components and adding additional functions to the existing parts. In this study, the goal is to study the process parameters of DED process, which includes laser power, feed rate, powder feed rate, stepover distance and layer thickness. The focused material is PH15-5 which is a precipitation hardened martensitic stainless steel. The geometrical properties and mechanical properties of PH15-5 would be investigated to optimize the process parameters. Design of experiments (DOE) and Analysis of variances (ANOVA) was performed to determine the influencing factors. The layer thickness was found as the factor which significantly affects the geometrical accuracy. The laser power has been proven with remarkable effects on the density and hardness. Finally, the recommendation of further optimization and future work are proposed.