The　zirconium　alloy　clad　tube　provides　a　protection　and　room　for　the　nuclear　reaction　of　fuel　rods　in　the　nuclear　power　plant.　The　clad　tubes　are　usually　sealed　up　by　pressure　resistance　welding　with　the　end　plugs.　The　non-equilibrium　physical　metallurgy,　caused　by　welding,　often　brings　about　a　non-uniformity　of　microstructure　and　corrosion　resistance　in　the　zirconium　alloy　joint.　In　order　to　investigate　the　influence　of　the　microstructure　on　the　service　performance　of　the　welded　joint　corrosion　experiments　were　designed　and　conducted　by　amplifying　the　mechanical　and　heat-affected　zone　in　the　joint,　using　a　thermal　and　mechanical　simulation　machine.　It　was　shown　that　the　amplified　sample　had　the　similar　microstructure　and　micro　hardness　with　the　mechanical　and　heat-affected　zone.　The　corrosion　rate　of　the　mechanical　and　heat-affected　zone　was　higher　than　that　of　the　base　metal　of　the　clad　tube.　A　heat　treatment　after　welding　was　proposed　to　weaken　the　influence　of　microstructure　difference　on　its　corrosive　resistance.　It　was　shown　that　the　corrosive　resistance　could　be　improved　by　modifying　the　microstructure　appearance　and　the　distribution　of　the　second　phase　particles.　©　2025　Korean　Nuclear　Society