Heat Treated Microstructures and Properties of Additively Manufactured IN718 Superalloy

The effect of fabrication parameters was studied on the microstructural evolutions and mechanical properties of IN718 superalloy selective laser melted samples. The samples were prepared with two different scan strategies, scan speed and hatch spacing. It was found that in a given scan speed, the scan strategy affected the final density of the samples. After heat treatment, in addition to recrystallized grains, columnar grains were elongated in build direction and effective heat flow was observed during solidification. The hardness values of heat-treated samples revealed an increase of 27–40% compared to the as-fabricated ones (from 285–330 to 450–480 HV). The hardness level of the present work samples reached an upper limit of other results before and after heat treatment.