The　crack-free　H13　block　was　deposited　through　additive　manufacturing　with　the　cold　metal　transfer　technology.　The　internal　3D　pore　distribution,　the　microstructural　evolution,　and　the　mechanical　performances　were　explored.　A　negligible　porosity　with　dispersive-distribution　and　spherical-shape　below　0.001%　guaranteed　a　sound　metallurgical　bonding　within　the　as-deposited　part.　The　martensite　laths　growth　direction　varied　dramatically　with　a　very　short　position　variation,　as　well　as　the　block-like　size-inconsistent　delta-ferrite　presence　in　the　overlap　zone,　which　were　mainly　generated　by　the　thermal　flux　direction　from　the　center　to　margin　within　a　single　arc　track.　Massive　second-phase　particles　with　morphology-diversity　and　size-nonuniformity　were　precipitated,　indicating　a　strong　dependency　with　the　intrinsic　heating　treatment.　The　enhanced　microhardness　in　the　body　zone　was　attributed　to　the　martensite　strengthening　mechanism,　while　slightly　low　hardness　was　produced　due　to　the　soft　delta-ferrite　formation.　When　compared　with　the　other　zones,　the　enhanced　ultimate　tensile　strength　was　obtained　in　the　body　zone　at　the　expense　of　tensile　ductility,　revealing　a　positive　relationship　with　the　rise　of　hard　martensite　percentage.　This　work　demonstrated　that　a　crack-free　H13　block　with　limited　porosity　and　desirable　mechanical　properties　was　deposited　using　the　present　technology,　despite　the　nonhomogeneous　microstructures.　(C)　2018　Elsevier　B.V.　All　rights　reserved.