AL6XN vs 254SMO: Sib piv Ob Super Austenitic Stainless Steels rau Marine Applications

Thaum tus qauv316L stainless hlautsis muaj zog txaus rau dej hiav txwv, ntug dej hiav txwv, los yog cov tshuaj chloride aggressive, engineers ncav cuag ib tsev neeg me me ntawm "6% molybdenum" super- qib austenitic - thiab AL6XN thiab 254SMO yog ob feem ntau cov tswv cuab ntawm tsev neeg ntawd. Ob leeg xa cov pitting zoo dua thiab crevice corrosion tsis kam tshaj tus qauv austenitic stainless hlau, thiab ob qho tib si yog cov neeg sib tw tiag tiag rau tib daim ntawv thov marine thiab desalination. Phau ntawv qhia no muab piv rau lawv ncaj qha - muaj pes tsawg leeg, pitting tsis kam, kev ntxhov siab corrosion cracking tus cwj pwm, lub luag hauj lwm ntawm tooj liab, thiab cov tswv yim xaiv cov kev taw qhia - kom paub meej qhov twg ob qib yog functionality sib npaug thiab qhov twg muaj lub ntsiab lus sib txawv tiag tiag.

Dab tsi yog AL6XN thiab 254SMO, thiab Vim Li Cas Lawv Thiaj Pom Zoo "Super Austenitic"?

AL6XN thiab 254SMO yog ob qho tib si super- austenitic stainless hlau uas muaj kwv yees li 6% molybdenum thiab siab nitrogen cov ntsiab lus, muab tso rau hauv cov qib kev ua tau zoo tshaj tus qauv 300-series qib xws li 316L thiab squarely tsom rau qhov xav tau tshaj plaws, tshwj xeeb tshaj yog cov dej hiav txwv.

"Super-austenitic" yog kev lag luam tsis raug cai tab sis dav siv kev lag luam faib rau austenitic stainless hlau uas nws cov ntsiab lus alloy - tshwj xeeb yog molybdenum thiab nitrogen - mus zoo tshaj tus qauv 300-series compositions, xa ib kauj ruam - hloov kev txhim kho nyob rau hauv lub zos corrosion kuj es ib tug creeper. Ob leeg AL6XN (UNS N08367) thiab 254SMO (UNS S31254) belongs rau cov tsev neeg tshwj xeeb "6% Mo" nyob rau hauv pawg no, ib qho kev xaiv uas qhia txog lawv cov ntsiab lus molybdenum zoo sib xws thiab, tsis yog coincidentally, lawv cov qib zoo sib xws ntawm pitting thiab crevice corrosion kuj.

Ob qib tau tsim thiab ua lag luam tshwj xeeb los sib tw rau tib qho kev xav tau - seawater systems, desalination nroj tsuag, offshore cov cuab yeej - yog vim li cas lawv thiaj li nquag sib piv ncaj qha rau ib leeg es tsis yog tawm tsam ntau dua qib sib txawv.

Dab tsi yog Qhov Tseem Ceeb Qhov Sib Txawv Ntawm AL6XN thiab 254SMO?

AL6XN thiab 254SMO sib koom yuav luag zoo tib yam molybdenum thiab nitrogen cov ntsiab lus, tab sis lawv sib txawv hauv ob txoj kev tshwj xeeb - AL6XN nqa cov ntsiab lus siab dua nickel cov ntsiab lus, thaum 254SMO suav nrog cov tooj liab ntxiv uas AL6XN tsis - thiab ob qhov sib txawv, tsis yog tag nrho cov ntsiab lus alloy, yog dab tsi distingu's profiles.

Ib sab -los ntawm- sab kev sib piv:

Table 1. Tus neeg sawv cev nominal muaj pes tsawg leeg rau AL6XN (UNS N08367) thiab 254SMO (UNS S31254). Cov txiaj ntsig yog kev piav qhia thiab sib npaug; lees paub qhov txwv tsis pub dhau qhov tam sim no ntawm ASTM A240 / A480 lossis cov lus qhia siv tau ua ntej siv hauv kev yuav khoom lossis tsim cov ntaub ntawv.

Nws yog ib qho tsim nyog yuav tsum nco ntsoov tias ob qib no nyob ze li cas hauv lawv qhov tseem ceeb pitting-tsis kam chemistry - chromium, molybdenum, thiab nitrogen yog tag nrho nyob rau hauv ib qho zoo sib xws - uas yog vim li cas lawv raug suav tias yog cov neeg sib tw ze dua li cov qib ua haujlwm sib txawv ntawm cov niches. Cov ntsiab lus sib txawv yog concentrated nyob rau hauv cov ntsiab lus nickel thiab muaj los yog tsis muaj tooj liab, ob qho tib si tham hauv cov ntsiab lus hauv qab no.

Yuav Ua Li Cas AL6XN thiab 254SMO Sib Piv hauv Pitting thiab Crevice Corrosion Resistance?

AL6XN thiab 254SMO muaj cov lej zoo sib xws Pitting Resistance Equivalent Numbers (PREN), ob qho tib si zoo siab tshaj 40, txhais tau hais tias ob qib muab qhov tseem ceeb sib piv rau cov tshuaj chloride pitting thiab crevice corrosion - ib qho tseem ceeb tshaj plaws khoom rau seawater thiab marine kev pab cuam.

PREN yog xam los ntawm ib tug alloy lub chromium, molybdenum, thiab nitrogen cov ntsiab lus:

PREN=%Cr + 3.3 × %Mo + 16 × %N

Siv cov qauv no nrog cov neeg sawv cev sib xyaw, AL6XN feem ntau ua rau PREN nyob ib puag ncig 45–46, thaum 254SMO feem ntau ua rau PREN nyob ib puag ncig 43–45 - qhov sib txawv me me uas nws tsis sawv cev rau qhov muaj txiaj ntsig zoo sib txawv hauv cov kev pabcuam feem ntau. Ob qhov txiaj ntsig muab cov qhab nia zoo tshaj tus qauv 316L (PREN ≈ 24–26) thiab txawm tias siab dua ntau qib duplex stainless hlau, uas yog vim li cas ob qho tib si AL6XN thiab 254SMO tau suav tias tsim nyog rau kev pabcuam dej hiav txwv puv dej, ib qho xwm txheej uas tus qauv austenitic stainless hlau tsis haum rau.

Hauv kev xyaum, qhov no txhais tau hais tias qhov sib piv ntawm pitting thiab crevice corrosion kuj ntawm AL6XN thiab 254SMO tsis tshua muaj kev txiav txim siab xaiv ntawm nws tus kheej - cov ntsiab lus sib txawv yog cov ntsiab lus nickel thiab tooj liab, npog tom ntej.

Cov ntsiab lus Nickel cuam tshuam li cas rau kev ntxhov siab Corrosion Cracking Resistance nyob rau hauv txhua qib?

AL6XN qhov tshwj xeeb ntau dua nickel cov ntsiab lus - kwv yees li 24% piv nrog kwv yees li 18% hauv 254SMO - muab qhov zoo dua rau kev tiv thaiv chloride-induced stress corrosion cracking, ua rau nws yog ib qho kev xaiv tshwj xeeb rau kub, stressed chloride ib puag ncig qhov kev tsis ua hauj lwm no, ntau dua li kev txhawj xeeb ntawm pitting.

Chloride-induced stress corrosion cracking is a well-documented failure mode in austenitic stainless steels under tensile stress in hot chloride ib puag ncig, thiab cov ntsiab lus npib tsib xee muaj zog, zoo- tsim kev sib raug zoo los tiv thaiv nws - ntau dua nickel cov ntsiab lus feem ntau txo qhov kev raug mob. AL6XN cov ntsiab lus npib tsib xee zaum siab tshaj 254SMO's, uas yog qhov tseeb, chemistry- tau tsav qhov sib txawv ntawm ob qib ntau dua li qhov sib txawv me ntsis.

Qhov no tseem ceeb tshaj plaws hauv cov kev pabcuam tshwj xeeb - nce siab- qhov kub ntawm cov tshuaj chloride raug ua ke nrog cov kev ntxhov siab tensile, xws li qee cov cua kub exchanger tubing los yog cov khoom nyuab siab hauv cov dej hiav txwv kub los yog brine kev pab cuam - qhov twg AL6XN cov nickel kom zoo dua tuaj yeem txhais ua qhov sib txawv ntawm qhov kev pab cuam lub neej, txawm tias ob qho tib si PREN.

Puas yog Copper Ntxiv hauv 254SMO muab qhov txiaj ntsig Corrosion Advantage?

254SMO cov tooj liab ntxiv muab cov txiaj ntsig me me, tsom mus rau qee yam kev txo cov kua qaub thiab cov txheej txheem tshwj xeeb - tshuaj lom neeg cov xwm txheej - zoo ib yam hauv cov ntsiab lus rau tooj liab lub luag haujlwm hauv qib zoo li 904L - tab sis nws tsis hloov pauv 254SMO lub hauv paus pitting tsis kam, uas yog tsav los ntawm cov ntsiab lus ntawm 6XB feem ntau thiab cov ntsiab lus ntawm nitrogen.

Copper cov txiaj ntsig corrosion hauv stainless hlau metallurgy yog qhov tshwj xeeb tshaj li qhov dav: nws nyiam txhim kho kev ua haujlwm hauv qee qhov txo cov kua qaub thiab sulfuric -acid- nyob ib sab es tsis xa cov kev txhim kho dav dav thoob plaws txhua qhov kev txhim kho corrosion. Qhov no txhais tau hais tias 254SMO qhov sib ntxiv tooj liab yog qhov tseeb, qhov txawv ntawm qhov tseeb - thiab ib qho laj thawj nws tau nquag teev nyob rau hauv cov ntaub so ntswg thiab cov ntawv bleach cog cov cuab yeej thiab qee yam flue gas desulfurization tej yam kev mob uas qhov tshwj xeeb chemistry tau txais txiaj ntsig - tab sis nws yuav tsum tsis txhob nyeem ua 254SMO categorically superior rau

AL6XN hla lub rooj tsavxwm. Hauv cov tshuaj dawb huv pitting thiab crevice corrosion kuj, ob qib tseem nyob ze cov neeg sib tw, raws li lawv cov txiaj ntsig zoo sib xws PREN qhia; tooj liab qhov kom zoo dua yog mob- tshwj xeeb, tsis yog universal.

Yuav Ua Li Cas Ob Qib Sib Piv hauv Mechanical Properties thiab Fabricability?

AL6XN thiab 254SMO muaj cov khoom siv dav dav zoo sib xws thiab kev tsim cov yam ntxwv zoo li siab -nitrogen super- austenitic stainless hlau, ob qho tib si muab lub zog siab dua li tus qauv 316L vim muaj zog nitrogen, nrog rau vuam yuav tsum tau ceev faj tswj cov cua sov thiab muab tub lim xaiv hlau nyob rau hauv ob qho tib si qib los tiv thaiv corrosion kev ua tau zoo.

Ob qib tau txais txiaj ntsig los ntawm nitrogen cov khoom siv - cov kev daws teeb meem ntxiv dag zog rau lawv, ua rau lawv muaj txiaj ntsig zoo dua cov txiaj ntsig zoo dua li qib qib austenitic zoo li 316L thaum khaws cov khoom zoo thiab tawv, nrog rau qhov kub thiab txias. Fabrication txiav txim siab kuj zoo ib yam ntawm ob: ob qho tib si yuav tsum tau saib xyuas rau cov cua sov tawm tswv yim thaum lub sij hawm vuam kom tsis txhob tsim cov deleterious intermetallic theem uas muaj peev xwm nyob rau hauv lub zos degrade corrosion kuj, thiab ob qho tib si feem ntau welded nrog ib tug sib piv los yog tshaj -alloyed muab tub lim hlau los xyuas kom meej lub weld deposit tuav txaus corrosion kev kawm ntawm lub hauv paus hlau.

Tsis yog qib twg tuav qhov kev txiav txim siab ua tau zoo dua lwm tus hauv kev nthuav dav dav - ob qho tib si xav tau ntau dua rau vuam kom raug dua li tus qauv 316L, ua raws li lawv cov ntsiab lus siab dua, thiab ob qho tib si muab nqi zog rau cov fabricators paub txog high- alloy super- austenitic vuam xyaum.

Qib twg yog qhov tsim nyog rau cov ntawv thov tshwj xeeb Marine thiab Desalination?

Rau feem ntau seawater piping, dav marine, thiab desalination daim ntaub ntawv, AL6XN thiab 254SMO yog functionally interchangeable xaiv, nrog rau cov tswv yim xaiv feem ntau tsav los ntawm lub regional muaj thiab tshwj xeeb txheej txheem chemistry tshaj los ntawm ib tug txiav txim siab qhov sib txawv - AL6XN's npib tsib xee ntug nyiam 4 Stressed ntxiv 2 chloride tej yam kev pab cuam. txo - cov txheej txheem kua qaub.

Ib qho kev sib piv ntawm kev tsim nyog nyob rau hauv kev siv marine thiab txheej txheem:

Table 2. Tus neeg sawv cev tsim nyog sib piv, AL6XN vs . 254SMO, thoob plaws hauv kev siv marine thiab txheej txheem.

Yuav Ua Li Cas Muaj thiab Nqi Sib Piv Ntawm AL6XN thiab 254SMO?

AL6XN thiab 254SMO yog ob qho tib si tshwj xeeb, qis dua - cov khoom ntim piv nrog cov qib austenitic tus qauv, thiab lawv cov nqi thiab cov khoom muaj muaj dav sib piv rau ib leeg, txawm tias cov qauv hauv cheeb tsam stocking thiab cov khoom tsim tshwj xeeb muaj peev xwm txaus siab rau ib qib ntawm lwm tus hauv lub khw muag khoom lossis lub sijhawm ua haujlwm.

Vim tias ob qib sib piv cov ntsiab lus siab zoo sib xws - tshwj xeeb tshaj yog tus nqi 6% molybdenum thiab nce npib tsib xee lossis tooj liab ntxiv - tsis muaj qhov pom tseeb, tus nqi dav dav dua li lwm tus ntawm ib qho zoo li-rau-zoo li hauv paus; qhov project- tus nqi tshwj xeeb feem ntau qhia txog kev sib raug zoo ntawm zeb, kev txiav txim ntim, thiab cov khoom tsim muaj ntau dua li qhov sib txawv ntawm tus nqi sib txawv hauv cov hlau alloy nws tus kheej. Qhov no yog qhov ua tau zoo, tsis yog -metallurgical yam tsim nyog lees paub thaum ntxov hauv ib qhov project: xyuas seb qib twg cov khoom lag luam nyiam nyob rau hauv cov khoom tsim nyog (phaj, yeeb nkab, fittings, tubing) thiab lub sij hawm txhuas tuaj yeem txiav txim siab qhov kev xaiv raws li qhov kev sib txawv me me uas tau hais los saum toj no, muab qhov zoo sib xws ntawm ob qib kev ua tau zoo.

Cov ntsiab lus xaiv cov tswv yim

• Qhov kev xav zoo li qub: AL6XN thiab 254SMO yog cov neeg sib tw kev sib raug zoo rau cov qauv seawater thiab marine chloride kev pabcuam.
• Txaus siab rau AL6XN thaum kub, ntxhov siab chloride tej yam kev mob ua rau muaj kev ntxhov siab corrosion cracking tsis kam tswj kev txhawj xeeb.
• Txaus siab rau 254SMO thaum cov txheej txheem ib puag ncig suav nrog kev txo qis -acid lossis bleach- cog chemistry qhov twg tooj liab cov txiaj ntsig siv.
• Thaum tsis muaj qhov xwm txheej kom meej meej, ua raws li qhov kev txiav txim siab zaum kawg ntawm tus neeg xa khoom muaj, lub sijhawm ua haujlwm, thiab tus nqi ntawm qhov project es tsis yog qhov sib txawv ntawm PREN.

Cov lus nug nquag

Puas yog AL6XN thiab 254SMO hloov pauv tau nyob rau hauv feem ntau marine specifications?

Hauv ntau daim ntawv thov dej hiav txwv thiab marine chloride, yog - lawv cov txiaj ntsig zoo sib xws PREN txhais tau hais tias ob qho tib si xa cov pitting thiab crevice corrosion kuj, txawm hais tias qhov project specifications, vuam txheej txheem tsim nyog, los yog ib qho kev nyuaj siab corrosion cracking los yog txheej txheem -kev txhawj xeeb txog chemistry tuaj yeem ua rau ib qib uas tsim nyog los yog xav tau kev xaiv.

Puas yog qib twg suav tias yog duplex stainless hlau?

Tsis yog. Ob leeg AL6XN thiab 254SMO yog tag nrho austenitic, ib zaug -theem super- qib austenitic, tsis duplex (austenitic- ferritic) stainless hlau; lawv cov kev tiv thaiv corrosion siab heev los ntawm kev siab molybdenum, nitrogen, npib tsib xee, thiab (hauv 254SMO cov ntaub ntawv) tooj liab cov ntsiab lus nyob rau hauv cov qauv austenitic.

AL6XN thiab 254SMO puas tuaj yeem txuas rau ib leeg hauv tib lub cev?

Yog lawm, kev hloov welds ntawm ob qib feem ntau ua tau nrog ib qho tsim nyog super- austenitic muab tub lim hlau, thiab qhov no tsis yog qhov txawv txav hauv cov haujlwm uas qhia txog cov khoom sib txawv los ntawm cov chaw muag khoom lossis cov khoom lag luam thoob plaws hauv ib qho.

Puas yog ob qib ua tau zoo hauv kev pabcuam dej hiav txwv puv dej?

Yog lawm, ob qho tib si AL6XN thiab 254SMO yog dav suav hais tias tsim nyog rau tag nrho cov seawater immersion, tsis zoo li tus qauv 316L, uas feem ntau tsis pom zoo rau kev txuas ntxiv mus rau hauv dej hiav txwv vim nws qhov sib piv qis dua PREN thiab siab dua pitting txaus ntshai.

Puas yog nickel cov ntsiab lus siab dua hauv AL6XN tseem txhim kho nws cov pitting dav dav piv nrog 254SMO?

Tsis tseem ceeb - npib tsib xee thawj corrosion-txog cov txiaj ntsig yog kev ntxhov siab corrosion cracking tsis kam ntau dua pitting, uas yog vim li cas AL6XN cov ntsiab lus ntau dua nickel tsis txhais ua cov khoom siv ntau dua PREN dua 254SMO; pitting tsis kam hauv ob qib yog tswj hwm los ntawm lawv cov chromium zoo sib xws, molybdenum, thiab nitrogen cov ntsiab lus.