Investigation of the influence of process parameters for directed energy deposition on mechanical properties of SS316L via experiments

• Main Author: Ong, Jiang Cai
• Other Authors: Li Hua
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/168345
• Institution: Nanyang Technological University

Directed Energy Deposition (DED) is an Additive Manufacturing (AM) process that is gaining traction amongst various industries as it has many benefits and a huge potential for future integration. This process can be used to create complex, functional metal parts and aid in localised repair, removing the need to create the part from scratch. 316L stainless steel is a good candidate for DED as it has high corrosion resistance, formability and suitable for high temperature applications. However, process parameters in AM systems can drastically affect the mechanical properties of the deposition, influencing its structural integrity. Hence the need for optimisation. In this study, the effects of 5 process parameters are investigated for its influence on the mechanical properties of printed SS316 specimens. Laser power, scanning speed, powder mass flow rate, XY-incremental ratio, and Z-incremental ratio were varied using Central Composite Design and Fractional Factorial Design to generate sets of process parameters for tensile and Vickers hardness experimentation. Furthermore, ANOVA was used to identify significant interactions and conduct response optimisation. The optimised set of process parameters were found to be laser power (1205.98W), scanning speed (2126.60mm/min), powder mass flow rate (19.27), XY-incremental ratio (0.44), and Z-incremental ratio (1.07). Interactions between low laser power (800W) with low XY-incremental ratio (0.5) and high scanning speed (>2000mm/min) with high powder mass flow rate (0.7g/min) was found to result in higher values of ultimate tensile strength. For optimal elongation of 42%, laser power of 1200W is required. 16 g/min for powder mass flow rate performed slight better than other values.