Electron Beam Welding of Selective Laser Melted Inconel 718
Abstract
Selective Laser Melting (SLM) can produce near-net shaped parts, but their sizes are limited by the small dimensions of current powder bed fusion machines. This research applies Electron Beam Welding (EBW) to join SLM’ed Inconel 718 (IN718) parts by characterizing the welds based on their material and mechanical properties and comparing them with their rolled counterparts. Weld properties of the Hot Isostatically Pressed (HIP) samples were also compared. The dependent variable, electron beam heat input was varied between the range 180J/mm to 295J/mm to weld 12.7mm thick Inconel 718 samples. To analyze the quality of the welds, microhardness tests, tensile tests, and microstructure analysis of the fracture surfaces using optical and scanning electron microscope were executed. The chemical composition of various phase particles on the weld fracture surfaces was identified using the energy dispersive spectroscopy. Excellent weld penetration depths were achieved which were directly proportional to the electron beam heat input. Root void defects were observed at high heat inputs. SLM’ed IN718 samples had excellent yield and tensile strength that exceeded the rolled samples and the ASTM F3055-14a specification; however, they had inferior ductility. The HIP samples in this study were rather brittle. The brittleness of SLM’ed IN718 was due to the presence of brittle Laves phase, Nb-rich carbides, and Al-Ti-Oxides in the material matrix due to non-optimal SLM parameters. These issues can be reduced further by implementing optimal SLM parameters, and various post-processing techniques on the SLM’ed metal.
Subject
Electron Beam WeldingSelective Laser Melting
Inconel 718
Additive Manufacturing
3D printing
Tensile Testing
Microhardness
Scanning Electron Microscope
Energy Dispersive Spectroscopy
Microstructure
Hot Isostatic Pressing
Citation
Sali, Akash Rajendra (2020). Electron Beam Welding of Selective Laser Melted Inconel 718. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /200804.