CORROSION ntawm STAINLESS STEEL cov khoom

Stainless hlau yog cov hlau alloy uas muaj tsawg kawg yog 10.5% chromium. Cov chromium no tso cai rau tsim cov txheej txheej oxide nyias nyias ntawm cov hlau nto, los yog hu ua "passive txheej" thiab muab cov hlau tsis zoo rau nws cov ci ci.
Passive coatings zoo li no pab tiv thaiv corrosion ntawm hlau nto thiab yog li txhim kho corrosion kuj los ntawm kev nce tus nqi ntawm chromium hauv stainless hlau. Los ntawm kev sib txuas cov ntsiab lus xws li npib tsib xee thiab molybdenum, ntau yam stainless hlau alloys tuaj yeem tsim tau, muab cov hlau muaj txiaj ntsig zoo dua qub, xws li txhim kho formability thiab siab dua corrosion kuj.
Stainless hlau cov khoom tsim los ntawm steel yeeb nkab manufacturers yuav tsis corrode nyob rau hauv "natural" tej yam kev mob los yog dej nyob ib puag ncig, yog li ntawd, cutlery, dab dej, countertops, thiab lauj kaub ua los ntawm steel tsev stainless hlau yog feem ntau siv. Txawm li cas los xij, nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias cov khoom no yog "tsis muaj xeb" thiab tsis yog "stainless" thiab yog li qee qhov kev xeb yuav tshwm sim.

Dab tsi tuaj yeem ua rau stainless hlau corrode?
Corrosion, hauv nws cov lus piav qhia yooj yim tshaj plaws, yog tshuaj lom neeg cov tshuaj tiv thaiv uas cuam tshuam rau kev ncaj ncees ntawm cov hlau. Yog hais tias hlau los rau hauv kev sib cuag nrog ib tug electrolyte, xws li dej, oxygen, av, los yog lwm yam hlau, hom tshuaj no yuav tsim.
Cov hlau plam electrons tom qab cov tshuaj tiv thaiv tshuaj thiab yog li ua tsis muaj zog. Tom qab ntawd nws raug cuam tshuam rau lwm yam tshuaj lom neeg yav tom ntej, uas tuaj yeem tsim phenomena xws li corrosion, tawg, thiab qhov nyob rau hauv cov khoom kom txog thaum hlau tsis muaj zog.
Corrosion kuj tuaj yeem ua rau nws tus kheej perpetuating, txhais tau hais tias ib zaug nws pib nws yuav nyuaj rau nres. Qhov no tuaj yeem ua rau cov hlau ua nkig thaum corrosion mus txog qee theem thiab nws tuaj yeem tawg.

NYEEM NTAWV NTAWM KEV RUAJ NTSEG hauv STAINLESS STEEL
Uniform Corrosion
Hom corrosion feem ntau uas tuaj yeem cuam tshuam rau cov hlau tsis muaj steel thiab lwm yam hlau yog hu ua uniform corrosion. Qhov no yog qhov "uniform" kis ntawm corrosion nyob rau saum npoo ntawm cov khoom.
Interestingly, nws tseem paub tias yog ib qho ntawm ntau "benign" cov ntaub ntawv ntawm corrosion, txawm hais tias nws tuaj yeem npog thaj tsam loj ntawm cov hlau. Tseeb, nws qhov kev cuam tshuam ntawm cov khoom siv kev ua tau zoo yog ntsuas tau raws li nws tuaj yeem txheeb xyuas tau yooj yim.

Pitting Corrosion
Pitting corrosion tuaj yeem nyuaj rau kev kwv yees, paub txog, thiab sib txawv, lub ntsiab lus nws feem ntau suav hais tias yog ib qho kev phom sij tshaj plaws ntawm corrosion.
Qhov no yog ib qho chaw zoo heev ntawm corrosion nyob rau hauv qhov chaw me me ntawm pitting corrosion yog tsim los ntawm ib qho chaw anodic lossis cathodic chaw. Thaum lub qhov no ruaj khov, nws tuaj yeem "tsim" ntawm nws tus kheej kom lub qhov me me tuaj yeem yooj yim tsim cov kab noj hniav uas tuaj yeem ua tau ntau yam sib txawv thiab ntau thiab tsawg. Pitting corrosion feem ntau "migrate" downwards thiab tuaj yeem ua rau muaj kev phom sij tshwj xeeb vim tias yog sab laug tsis txheeb xyuas, txawm tias qhov chaw me me raug cuam tshuam, nws tuaj yeem ua rau cov hlau tsis ua haujlwm.

Crevice Corrosion
Crevice corrosion yog ib hom kev txhim kho hauv zos uas tshwm sim los ntawm ib puag ncig microscopic uas ob thaj tsam hlau muaj qhov sib txawv ion concentrations.
Nyob rau hauv cov chaw xws li ntxhua khaub ncaws, bolts, thiab cov pob qij txha uas muaj cov tsheb me me uas tso cai rau cov kua qaub nkag mus, daim ntawv no ntawm corrosion yuav tshwm sim. Qhov txo qis ntawm cov pa oxygen yog vim tsis muaj kev ncig, yog li cov txheej txheem passive tsis tshwm sim. Qhov pH sib npaug ntawm qhov aperture yog tom qab ntawd cuam tshuam thiab ua rau muaj qhov tsis sib xws ntawm thaj chaw no thiab sab nrauv. Qhov tseeb, qhov no ua rau cov nqi corrosion ntau dua thiab tuaj yeem ua rau hnyav dua los ntawm qhov kub thiab txias. Siv cov qauv tsim kom tsim nyog los txo qhov kev pheej hmoo ntawm kev xeb tawg yog ib txoj hauv kev los tiv thaiv daim ntawv no ntawm corrosion.

Electrochemical corrosion
Yog tias immersed nyob rau hauv ib tug corrosive los yog conductive tov, ob electrochemically sib txawv hlau los rau hauv kev sib cuag, tsim ib tug khiav ntawm electrons ntawm lawv. Vim tias cov hlau tsis muaj zog yog cov anode, cov hlau tsis muaj corrosion kuj feem ntau cuam tshuam. Daim ntawv no ntawm corrosion yog hu ua galvanic corrosion los yog bimetallic corrosion.