Microstructure and Mechanical Properties of New Nickel-Based Superalloys Fabricated by Selective Laser Melting at Low Energy Density

Abstract:

ZGH401 alloy was prepared under varying laser power levels and scanning speeds by the orthogonal test method using selective laser melting (SLM). The effect of different energy densities on microstructure and mechanical properties of the formed alloy was investigated. The microstructure of ZGH401 was analyzed by scanning electron microscope, electron back-scattered diffraction, and electron probe microanalysis. The results show that the defects of the as-built ZGH401 are gradually reduced, the relative density is correspondingly enhanced with increasing the energy density, and the ultimate density can reach 99.6%. An increase in laser power leads to a corresponding rise in hardness of ZGH401, while a faster scanning speed reduces the residual stress in as-built ZGH401 samples. In addition, better tensile properties are achieved at room temperature due to more grain boundaries perpendicular to the build direction than parallel to the build direction. The precipitated phases are identified as carbides and Laves phases via chemical composition analysis, with fewer carbides observed at the molten pool boundaries than within the molten pools.