The　cold　metal　transfer　(CMT)　based　wire-arc　additive　manufacturing　(WAAM)　technology　has　been　widely　recognized　as　a　suitable　method　for　fabricating　large-sized　aluminum　alloy　components.　However,　the　poor　mechanical　properties　of　the　as-deposited　aluminum　alloys　prevent　their　wide　application　in　the　aerospace　industry.　In　this　paper,　three　categories　of　samples　with　different　interlayer　deformation　strains　were　fabricated　by　WAAM.　These　samples　were　further　investigated　to　evaluate　the　effects　of　interlayer　deformation　on　the　mechanical　properties,　microstructural　evolution,　and　the　underlying　strengthening　mechanism.　The　grain　size　distribution　and　internal　sub-microstructure　were　characterized　by　electron　backscatter　diffraction　(EBSD)　and　transmission　electron　microscopy　(TEM).　As　compared　to　the　as-deposited　samples,　the　yield　strength　and　ultimate　tensile　strength　of　the　50.8%　deformed　sample　increased　from　148.4　to　240.9　MPa　and　from　288.6　to　334.6　MPa,　respectively.　The　microstructure　of　the　samples　with　interlayer　hammering　exhibited　highly　refined　grain,　which　is　a　combined　result　of　deformation　and　subsequent　intrinsic　in-situ　heat　treatment　induced　by　the　next　deposition　layer.　The　recrystallized　grains　can　be　further　deformed　with　subsequent　hammering,　which　leads　to　an　increase　in　dislocation　density　and　contributes　to　an　increase　in　ultimate　tensile　strength　of　the　additively　manufactured　2319　aluminum　alloys　with　interlayer　hammering.　©　2020　Elsevier　B.V.