Stainless-clad　(SC)　bimetallic　steel　is　an　advanced　laminated　material　that　offers　an　economical　solution　for　structures　in　corrosive　environments.　However,　its　mechanical　performance　and　design　methods　are　not　yet　established,　limiting　the　application　of　these　high-performance　materials.　This　paper　experimentally　investigated　the　axial　compressive　behavior　and　performance　deterioration　of　SC　bimetallic　square　steel　tubes　in　a　chloride　ion　environment.　A　total　of　33　SC　bimetallic　steel　coupons　and　square　tube　members　were　employed　for　salt　spray　accelerated　corrosion　tests.　After　corrosion,　the　surface　morphology　of　the　corroded　square　steel　tube　was　obtained　by　the　three-dimensional　(3D)　scanning　method　to　identify　the　corrosion　depth　and　then　establish　the　correlation　between　corrosion　depth　and　material　properties.　The　monotonic　axial　compression　tests　of　the　corroded　square　steel　tube　were　thereafter　carried　out,　and　the　deterioration　pattern　was　analyzed,　in　terms　of　the　failure　mode,　local　buckling　behavior,　strength　capacity,　and　ductility.　The　feasibility　of　current　national　codes　to　estimate　the　mechanical　properties　was　evaluated　and　improved.　The　results　demonstrated　that　the　corrosion　resistance　of　SC　bimetallic　square　steel　tubes　was　much　better　than　that　of　carbon　square　steel　tubes　in　chloride　ion　environments,　showing　noticeably　smoother　surface　morphology　and　lower　deterioration　in　the　ultimate　capacity　(half　of　low-carbon　steel)　and　ductility　(1/5　of　low-carbon　steel).　The　proposed　formula　can　reasonably　predict　the　mechanical　properties　of　corroded　SC　bimetallic　steel　tubes,　and　fill　the　gap　in　current　national　codes.　©　2025　Elsevier　Ltd