Laser Directed Energy Deposition based Additive Manufacturing of Copper: Process Development and Material Characterizations

摘要

This paper reports a systematic investigation on the Laser Directed Energy Deposition (LDED) based additive manufacturing of bulk Cu structures; and microstructural and mechanical characterisation of these structures. Full factorial experiments are carried out by varying LDED process parameters for track deposition, and process window is identified in terms of Laser Energy per unit Powder Feed (LEPF). Further, the bulk deposition is carried out using three inter-layer processing schemes, like - constant LEPF, decreasing LEPF, and increasing LEPF in successive layers during deposition. Cu block deposited using increasing LEPF scheme yields relative density around 99.9% and X-ray diffraction reveals pure Cu phase with fine crystallites. Microstructural analysis shows the dominance of equiaxed grains, with an average size of 24.47 um. Further, an average micmhardness of 77 HV0.98 N, yield strength of 135 - 152 MPa and ultimate tensile strength (UTS) of 277 - 288 MPa are obtained for the deposited bulk Cu structures. The obtained UTS value is higher than the strength values available in the literature for wrought, laser powder bed fusion and LDED built Cu samples. The present study paves a methodology towards the successful deployment of the LDED process for the potential fabrication of Cu components and parts.