Effect of heat accumulation on microstructural inhomogeneity in a 3D-printed copper alloy

Abstract

Additive Manufacturing (AM) has been a popular method to produce small and intricate parts for prototypes and research studies to understand how its heat impacted on the printed parts. Directed Energy Deposition (DED) is one of the AM which has been utilised in many applications due to its high Degree of Freedom including rotation axis for ease of printability. If DED is frequently used, it is essential for us to understand the complexity it comes with it such as how heat affects the printed parts, how big the Heat Affected Zone (HAZ) is and etc to prevent pre-mature failure with the printed components. Hence, it is important to study them in-depth to avoid catastrophic event. This research has shown the existence of microstructure heterogeneity and the difference in tensile properties at different locations of the DED printed parts. The sample piece was printed using DED machine and six sample pieces were cut from top, middle and bottom locations for tensile test using tensile test machine as well as microstructure characterisation using various equipment such as Electron Backscatter Diffraction (EBSD), Field Emission Scanning Electron Microscope (FESEM) and etc. Microstructure phase coarse a phase was observed in the top and middle locations. On the other hand, the microstructure present in the bottom location shew the Widmanstätten α phase embedded in the β' matrix. For mechanical strength, bottom location had the best mechanical strengths. DED method is suitable for low quantity demand parts or customised design products.