Effect of heat treatment on microstructure and mechanical properties of GH4099 superalloy fabricated by selective laser melting

In this study, the effect of heat treatment on the microstructures and mechanical properties of GH4099 superalloy fabricated by selective laser melting (SLM) was investigated. The microstructures of the as-deposited sample mainly consisted of epitaxial growth columnar grains, and the formation of γ-γ′ eutectic phase was inhibited. After solution treatment, the molten pool boundaries and dendritic morphology in the as-deposited sample disappeared, and the dislocation density decreased apparently. The γ′ phase with size of approximately 10 nm precipitated in the matrix after aging treatment; thus, the tensile properties were improved. In addition, the corresponding relationship between the microstructures and yield strength of the SLM GH4099 superalloy was revealed, which would help to quantitatively evaluate the mechanical properties of alloys with different microstructures.