Microstructural evolution and mechanical performances of selective laser melting Inconel 718 from low to high laser power

Abstract

In this work, selective laser melting (SLM) technology was used to manufacture the Inconel 718 alloy from low to high power and the effects of laser power on formability, microstructural evolution and tensile performance were studied. It was found that the fully dense forming process window becomes narrower as the laser power increases. Moreover, as the laser power increases from 500 W to 2000 W, the build rate is increased from 6 mm3/s to 14.3 mm3/s. In comparison, the coarser γ-dendrite, the more precipitation of Laves phase and the finer columnar grain can be obtained under a higher laser power. Besides, the <001> texture in the Inconel 718 samples can be reduced at a higher laser power. The tensile strength exhibits an obvious decreasing trend as the laser power increases. At the lowest laser power of 500 W, tensile strength reaches the highest values with the ultimate tensile strength of 1122 MPa and yield strength of 828 MPa, because of the higher relative density, the finer γ-dendrite and the less Laves phase. But the increase of the laser power benefits the improvement of elongation. When the laser power further increases to 1500 W, the elongation reaches its highest value of 33.45% due to the finer columnar grains.