2205 vs 2507 Duplex Stainless Steels: Standard vs Super Duplex Performance

 

Dab tsi yog lawv cov ntsiab lus tseem ceeb thiab cov cuab yeej cuab tam sib txawv?

2205 (UNS S32205) muaj 21-23% Cr, 4.5-6.5% Ni, 2.5-3.5% Mo, thiab 0.08-0.20% N, nrog 50/50 ferrite-austen Nws muaj lub zog tawm los ntawm ntau dua lossis sib npaug ntawm 450MPa, ob zaug ntawm 316L, thiab Pitting Resistance Equivalent Number (PREN) ntawm ~ 33.2507 (UNS S32750) yog qib super duplex nrog 24-26% Cr, 6-8% Ni, 3-0.2% Mosting PREN mus rau ~ 42 thiab tawm lub zog rau ntau dua lossis sib npaug rau 550MPa. Nws cov chromium ntau dua, molybdenum, thiab nitrogen cov ntsiab lus txhawb kev tiv thaiv corrosion nyob deb tshaj 2205.Ob qib muaj kev qaug zog zoo heev thiab muaj txiaj ntsig zoo dua li cov hlau austenitic super zoo li 904L rau kev siv zog, siab-corrosion.

Yuav ua li cas lawv corrosion resistances piv nyob rau hauv aggressive chloride ib puag ncig?

2205 ua tau zoo nyob rau hauv cov dej hiav txwv thiab cov tshuaj me me acid chloride, tiv taus pitting thiab crevice corrosion ntawm qhov kub txog li 50 degree, ua rau nws tsim nyog rau cov khoom siv fais fab ntawm ntug dej hiav txwv thiab cov tshuaj cia tso tsheb hlau luam.2507 txuas qhov kev ua haujlwm no mus rau qhov kub siab tshaj 60℃thiab hauv cov concentrated chloride media (piv txwv li, 20% NaCl05 kev daws teeb meem hauv zos). Nws kuj tiv taus kev ntxhov siab corrosion cracking (SCC) nyob rau hauv ib puag ncig roj qaub (H2S{10}}cov roj qhov dej).Nyob rau hauv acidic chloride tej yam kev mob (piv txwv li, dilute H2SO4 + NaCl), 2507's ntom passive zaj duab xis tseem ruaj khov, thaum 2205 tej zaum yuav muaj corrosion kuj ntawm high acid concentrations.

Hauv qhov xwm txheej twg yog 2507 qhov tsim nyog hloov kho los ntawm 2205?

2507 yog qhov yuav tsum tau ua rau cov khoom siv hauv dej hiav txwv thiab cov roj av, suav nrog cov taub dej, cov risers, thiab cov dej ntws, qhov chaw siab, cov tshuaj chloride siab, thiab cov roj qaub sib xyaw ua ke los tsim ultra- cov kev mob hnyav.Nws tseem yuav tsum tau rau cov seawater desalination nroj tsuag siv rov qab osmosis, qhov twg cov khoom raug cuam tshuam mus rau qhov siab ntawm - dej hiav txwv thiab qhov kub thiab txias. fittings.Rau cov ntawv thov qhov twg cov khoom tsis ua haujlwm yuav ua rau muaj kev pheej hmoo ntawm ib puag ncig lossis kev nyab xeeb, 2507 qhov kev cia siab zoo tshaj plaws ua rau nws tus nqi siab dua 2205.

Tus nqi thiab kev tsim khoom lag luam yog dab tsi- tawm ntawm ob qib duplex?

2507 tus nqi 30-50% ntau dua 2205 vim nws cov ntsiab lus alloy siab dua, ua rau 2205 qhov kev xaiv kev lag luam rau cov uas tsis yog- ib puag ncig tsis zoo xws li cov ntug dej hiav txwv architectural thiab kev siv tshuaj lom neeg.2507 muaj cov kev xav tau nruj dua vuam: nws xav tau qis dua -cov khoom siv hluav taws xob tsawg tshaj li 1 hli los yog welding. ferrite-austenite tshuav nyiaj li cas, thaum 2205 tuaj yeem ua siab ntev me ntsis siab dua cov khoom siv hluav taws xob (tsawg dua lossis sib npaug li 2.5kJ / hli) yam tsis muaj kev cuam tshuam ntawm microstructure.Ob qib yuav tsum muaj cov khoom sib xyaw duplex muab tub lim rau vuam-2507 siv super duplex fillers zoo li ER2594, thaum 2205 siv cov qauv duplex fillers zoo li ER2209.

Dab tsi yog qhov tseem ceeb ntawm kev tsim thiab tu cov lus qhia rau cov qib duplex?

Rau ob qho tib si 2205 thiab 2507, tsis txhob ncua ntev ntawm qhov kub thiab txias ntawm 300-900 degree, vim qhov no tuaj yeem ua rau cov nag lossis daus (sigma theem) uas txo cov tawv thiab corrosion kuj.Post- vuam tu (pickling thiab passivation) yog ib qho tseem ceeb rau kev tshem tawm cov yeeb yaj kiab passive; rau 2507, siv ib qho nitric-hydrofluoric acid pickle tshwj xeeb tsim rau cov qib super duplex.Regular microstructure tshuaj xyuas tau pom zoo rau 2507 cov khoom hauv cov kev pabcuam kub kub txhawm rau txheeb xyuas cov theem ntawm sigma, thaum 2205 yuav tsum tau saib xyuas tsawg dua nyob rau hauv ib puag ncig nruab nrab.