Microstructure and mechanical properties of nickel-based superalloy fabricated by laser powder-bed fusion using recycled powders

De-cheng Kong¹，Chao-fang Dong¹，Xiao-qing Ni²，Liang Zhang²，Rui-xue Li¹，Xing He¹，Cheng Man³，Xiao-gang Li¹

1. Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing2. Shanghai Engineering Research Center of 3D Printing Materials, Shanghai Research Institute of Materials3. School of Materials Science and Engineering, Ocean University of China

摘 要：Evaluating the recyclability of powders in additive manufacturing has been a long-term challenge. In this study, the microstructure and mechanical properties of a nickel-based superalloy fabricated by laser powder-bed fusion（LPBF） using recycled powders were investigated. Re-melted powder surfaces, satellite particles, and deformed powders were found in the recycled powders, combined with a high-oxygencontent surface layer. The increasing oxygen content led to the formation of high-density oxide inclusions; moreover, printing-induced cracks widely occurred and mainly formed along the grain boundaries in the as-built LPBF nickel-based superalloys fabricated using recycled powders. A little change in the Si or Mn content did not increase the hot cracking susceptibility（HCS） of the printed parts. The changing aspect ratio and the surface damage of the recycled powders might contribute to increasing the crack density. Moreover, the configuration of cracks in the as-built parts led to anisotropic mechanical properties, mainly resulting in extremely low ductility vertical to the building direction, and the cracks mainly propagated along the cellular boundary owing to the existence of a brittle precipitation phase.

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