Solidification structure and aging response of laser additive manufactured Inconel 718

The dendritic structure, element segregation and Laves phase morphology of laser additive manufactured Inconel 718 were controlled by regulating laser processing parameters. Two typical specimens with different as-fabricated microstructure were obtained. The responses of microstructure and mechanical property of the specimens to direct aging treatment were investigated. The high molten-pool cooling rate from the high laser power (P) of 1200 W and scanning speed (V) of 12 mm/s (P1200/V12) was found to refine the dendrite structure and reduce the Laves phase. The specimen with reduced Nb segregation and discrete Laves phase showed a good aging response with high hardness and tensile strength due to the high-density precipitation of Nb-rich hardening phase. The present work contributes to the control of the microstructure and mechanical properties of Inconel 718.