The　deformation　behavior　and　microstructural　evolution　of　as-cast　254SMO　super-austenitic　stainless　steel　(SASS)　were　studied　by　hot　compressive　tests　in　the　temperature　range　900-1200　degrees　C,　and　in　the　strain　rate　range　0.01-10　s(-1).　The　results　show　that　the　single　peak　characteristic　appears　on　almost　all　the　obtained　flow　curves,　indicating　that　DRX　is　the　primary　softening　mechanism.　Either　increasing　deformation　temperature　or　decreasing　strain　rate　makes　the　flow　stress　level　reduce　remarkably.　The　hot　deformation　activation　energy　and　the　stress　exponent　are　calculated　to　be　577.845　kJ/mol　and　4.62　by　the　regression　analysis　of　sine　hyperbolic　function,　respectively.　From　the　deformed　microstructures,　it　is　found　that　the　DRX　nucleates　mainly　through　grain　boundary　bulging　but　occasional　through　subgrain　evolution　only　occurred　at　high　strain　rates　and　high　temperatures.　The　critical　stress　and　corresponding　strain　for　DRX　can　be　expressed　through　the　dimensionless　parameter,　Z/A.　The　critical　ratios　of　sigma(c)/sigma(p)　and　epsilon(c)/epsilon(p)　are　also　identified,　which　are　0.98　and　0.72,　respectively.　Moreover,　the　DRX　kinetics　for　as-cast　254SMO　SASS　can　be　represented　in　the　form　of　Avrami　equation,　and　the　predicted　volume　fraction　of　new　grains　based　on　the　developed　model　agrees　well　with　the　experimental　results.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.