  Dislocation structures, chemical segregation, {\gamma ^{\prime}, {\gamma
^{\prime \prime}}, {\delta} precipitates and Laves phase were quantified within
the microstructures of Inconel 718 (IN718) produced by laser powder bed fusion
additive manufacturing (AM) and subjected to standard, direct aging, and
modified multi-step heat treatments. Additionally, heat-treated samples still
attached to the build plates vs. those removed were also documented for a
standard heat treatment. The effects of the different resulting microstructures
on room temperature strengths and elongations to failure is revealed. Knowledge
derived from these process structure property relationships was used to
engineer a super solvus solution anneal at 1020 degC for 15 minutes, followed
by aging at 720 degC for 24 hours heat treatment for AM-IN718 that eliminates
Laves and {\delta} phases, preserves AM specific dislocation cells that are
shown to be stabilized by MC carbide particles, and precipitates dense {\gamma
^{\prime} and {\gamma ^{\prime \prime}} nanoparticle populations. This
'optimized for AM-IN718 heat treatment' results in superior properties relative
to wrought/additively manufactured, then industry standard heat treated IN718:
relative increases of 7/10 percent in yield strength, 2/7 percent in ultimate
strength, and 23/57 percent in elongation to failure are realized,
respectively, regardless of as-built vs. machined surface finishes.
