Direct energy deposition process parameters influence on microstructure and geometry of a single-track deposition

• Main Author: Tan, Brandon Hong Po
• Other Authors: Li Hua
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/158447
• Institution: Nanyang Technological University

Direct Energy Deposition (DED) is a popular additive manufacturing (AM) method that excels in repairing, rapid prototyping and low volume part fabrication. It is widely used in different industries such as aerospace, medical, and military due to its significant advantages. 316L stainless steel has excellent resistance to corrosion and tensile properties, making it a popular material to work with when dealing with the DED process. In this project, three process parameters (laser power, scanning speed, powder mass flow rate) were varied with different values to see their relationship with the microstructure and geometry of a single track deposition. The microstructure analysis was done using an optical microscopy method. The results obtained concluded a relationship between the laser power and average grain length and width, where an increase in laser power will cause a decrease in both the average grain length and width. Furthermore, a tensile test found the mechanical properties for both the largest and smallest grain size. Where a larger grain size resulted in better mechanical properties. The geometry analysis was done using a digital microscope (Keyence, VHX-7000), where different geometry dimension readings were obtained. Generally, high laser power and low scanning speed settings will increase most of the geometry dimensions. At the same time, the powder mass flow rate will affect only the deposition/dilution height or area, and there isn’t any relationship with both deposition/dilution length.