The　LPBF　IN718　superalloy　has　great　potential　for　aerospace　applications.　However,　it　faces　challenges　in　large　residual　stress　and　brittle　Laves　phases　leading　to　premature　failure　of　the　material.　Improving　the　mechanical　properties　through　heat　treatment　is　a　general　approach.　This　study　investigated　the　effect　of　solution　heat　treatments　on　the　microstructure　and　mechanical　properties　of　LPBF　IN718　alloy.　The　alloy　was　heated　under　980　℃,　1020　℃,　and　1080　℃　for　1　hour,　followed　by　air　cooling.　Microstructural　evolution,　including　grain　size,　cellular　structure,　Laves　phase,　δ　phase,　and　annealing　twins,　was　quantitatively　analyzed　using　SEM,　EBSD,　and　TEM.　The　tensile　results　show　that　the　as-built　samples　have　excellent　tensile　strength　with　an　ultimate　tensile　strength　of　1121　MPa　and　a　yield　strength　of　887　MPa.　The　sample　after　solution　heat　treatment　at　1080　℃　shows　the　highest　plasticity,　which　is　46.4　%.　Theoretical　calculations　show　that　the　high　yield　strength　mainly　results　from　the　strengthening　effect　of　the　cellular　structure,　which　can　be　regarded　as　a　combination　of　dislocation　and　elemental　segregation　strengthening.　The　plasticity　of　the　alloy　increases　with　the　increasing　degree　of　recrystallization.　The　elimination　of　Laves　phases　and　the　formation　of　annealing　twins　are　the　key　factors　to　the　enhanced　plasticity　observed　in　the　samples　after　solution　heat　treatment　at　1080　℃.　©　2025