  Effective post-heat treatment is critical to achieve desired microstructure
for high-performance in additively manufactured (AM) components. In this work,
the influence of homogenization on microstructure-property relationship in
17-4PH steels has been investigated. Precipitation of NbC, oxides, and
{\epsilon}-Cu were observed in the as-built 17-4PH steels. To design an optimum
post-heat treatment, homogenization was performed at 1050oC for different times
followed by aging at 482oC for 1 hour. It was identified that homogenization
for 1 hour followed by aging leads to the best combination of strength and
ductility due to the refinement of martensite and prior austenite grains.
Improved tensile properties were achieved for the post-heat-treated alloys that
exceeded the traditionally fabricated 17-4PH steels. Through comprehensive
microstructure characterization, it was deduced that the incoherent
{\epsilon}-Cu precipitates in the as-built alloy were dissolved through
homogenization, and subsequently, re-precipitated as coherent Cu-rich clusters
during aging. This study demonstrates that altering the precipitation behavior
using post-heat treatment is an effective pathway to significantly improve the
mechanical properties of AM alloys.
