Effect of laser power on porosity and mechanical properties of GH4169 fabricated by laser melting deposition

Abstract

The porosity and mechanical properties of GH4169 (a precipitation strengthened nickel-base superalloy) specimens fabricated using the laser melting deposition technique at different laser powers were investigated. The results showed that the dendritic structure with the Laves phase and carbides embedded in the Ni-gamma matrix formed in the as-fabricated GH4169 due to the strong temperature gradient and the high cooling rates. Porosity remarkably decreased first and slightly increased subsequently as the laser power increased from 300 to 800 W. The lowest porosity of the specimens characterized by 3D X-ray tomography is 0.28%. The specimens fabricated at 600 W tensiled along the direction perpendicular to the building direction exhibit the average yield strength of 587 MPa, the ultimate tensile strength of 903 MPa, and the elongation at fracture of 13.6%. Furthermore, the fatigue limit of the 600 W fabricated specimens is 173.7 MPa corresponding to the fatigue ratio of 0.1. And the relationship among the porosity, laser power and mechanical properties is discussed.