Nickel-based　superalloys　are　designed　for　high-temperature　applications　and　exhibit　micro-deformation　mechanisms　distinct　from　those　observed　at　room　temperature　(RT).　This　paper　investigated　the　microstructure,　mechanical　properties　and　deformation　behaviors　of　laser　powder　bed　fusion　(LPBF)　GH3536　alloy　at　RT,　750　°C　and　815　°C　using　in-situ　scanning　electron　microscopy　(SEM)　micro-tensile　tests　combined　crystal　plasticity　finite-element　simulation.　The　results　show　that　as-built　LPBF　GH3536　alloy　presents　dendrite　microstructure　with　plenty　of　processing　cracks　and　pores.　Anisotropic　mechanical　properties　were　observed,　with　higher　strength　in　the　laser　scanning　direction　and　greater　elongation　to　fracture　in　the　building　direction.　As　the　temperature　rises,　both　strength　and　elongation　to　fracture　decrease,　with　the　rate　of　decline　gradually　accelerating.　The　processing　defects,　such　as　pores　and　microcracks,　are　the　main　reason　for　the　crack　initiation　and　fracture　during　tensile.　The　existence　of　melt　pool　boundaries　(MPBs)　and　dendrite　boundaries　are　responsible　for　the　crack　propagation.　At　high　temperatures,　low　dislocation　density　reduces　the　bonding　strength　of　MPBs　and　GBs,　causing　the　deformation　behavior　of　the　LPBF　GH3536　alloy　shift　from　ductile　at　RT　to　brittle　fracture　at　elevated　temperature　(ETs).　©　2025　Elsevier　Ltd