Post-processing is often applied to AM builds, but they can produce microstructural changes that dramatically alter the properties of that build. This talk will present a systematic investigation of the microstructures produced during isothermal or HIP post processing treatments and their effects on the observed mechanical properties and corrosion behavior that will identify the contributions arising from specific microstructural features. This study will focus on the microstructures that develop as a function of post-processing temperatures or HIP treatment, followed by a more in-depth examination of the characteristic microstructures associated with the different post-processing regimes for AM 316L stainless steel to reveal the influences of i) the fine cellular structure, ii) the AM grain structure, and iii) the porosity within the build on the observed properties of the material.