S31254 thiab S32760tsis tau tsim los sib tw ntawm txhua lub hauv ntej. Lawv tuaj los ntawm ob txoj kev xav ntawm metallurgical sib txawv, thiab zaj dab neeg hauv paus ntsiab lus tseem qhia tau hais tias lawv coj li cas hauv thaj chaw.
S31254 - txoj kev 6Mo super austenitic.Lub tswv yim ntawm no yog pib nrog cov qauv austenitic thiab thawb molybdenum txog li 6 feem pua, ntxiv 0.2 feem pua nitrogen, thiab tuav chromium ze 20 feem pua nrog npib tsib xee ib ncig ntawm 18 feem pua. Qhov tshwm sim yog ib zaug xwb -theem austenite uas tiv taus pitting thiab crevice nres nyob rau hauv kub chloride media qhov twg 316L thiab txawm 904L tso tseg. Cov qib tau tsim tau zoo los hloov titanium hauv dej hiav txwv-cov khoom siv hluav taws xob txias, thiab nws nqa cov kab ke hauv nws cov chemistry.
S32760 - txoj kev super duplex.Lub tswv yim duplex txawv: phua lub microstructure kwv yees li 50/50 ntawm austenite thiab ferrite, lean tawm cov npib tsib xee kim, khaws chromium ntawm 25 feem pua thiab molybdenum ze 3.5 feem pua, ces ntxiv nitrogen thiab ib qho me me tungsten ntxiv. Koj tau txais ob-theem alloy uas muaj zog dua, pheej yig dua ib kilo, thiab-tsawg kawg hauv nruab nrab chloride media-ib yam li pitting- tiv taus raws li qib 6Mo.
Yog li qhov kev xaiv tsis tshua muaj txog "uas yog ntau dua corrosion resistant" nyob rau hauv lub abstract. Nws yog hais txog hom kev ua tsis tiav uas koj tuaj yeem them tsawg kawg, koj tus neeg tsim khoom siv welds li cas, koj qhov cai hauv cheeb tsam lees txais li cas, thiab seb koj cov peev nyiaj tau txais txiaj ntsig li cas rau nickel volatility.
Nominal Composition Side by Sab
| Khoom (%) | S31254 (254 SMO) | S32760 (F55 / 1.4501) |
|---|---|---|
| Chromium | 19.5 – 20.5 | 24.0 – 26.0 |
| Nickel | 17.5 – 18.5 | 6.0 – 8.0 |
| Molybdenum | 6.0 – 6.5 | 3.0 – 4.0 |
| Nitrogen | 0.18 – 0.22 | 0.20 – 0.30 |
| Tungsten | - | 0.50 – 1.00 |
| Tooj | 0.50 – 1.00 | 0.50 – 1.00 |
| Cov pa roj carbon (max) | 0.020 | 0.030 |
| Hlau | tshuav nyiaj li cas | tshuav nyiaj li cas |
| Hom PREN | 43 – 46 | 40 – 43 |
Ob peb yam dhia tawm tam sim ntawd. S31254 nqa yuav luag peb npaug ntawm npib tsib xee ntawm S32760, uas yog ob qho tib si nws cov corrosion-resistant superpower (high nickel buffers tiv thaiv chloride stress corrosion cracking) thiab nws cov nqi vulnerability. S32760 them rau qhov nickel txiav nrog lub qhov rais ua haujlwm nruj dua thiab cov txheej txheem vuam xav tau ntau dua. Lub tungsten nyob rau hauv S32760 tsis zoo nkauj - nws txhim kho crevice corrosion kuj thiab slows down undesirable theem los nag thaum lub sij hawm tshav kub input.
Vim li cas PREN Ib Leeg Misleads Buyers
Pitting Resistance Equivalent Number, xam raws li PREN=Cr + 3.3(Mo + 0.5W) + 16N, yog tus shorthand feem ntau procurement specs siv rau qeb alloys. Los ntawm tus lej ntawd,S31254 thiab S32760 zoo li yuav luag sib hloov, ob qho tib si zaum hauv qis - mus rau -mid 40s.
Qhov teeb meem yog tias PREN ntes tsuas yog ib qho tsis ua hauj lwm hom: tsis kam mus rau qhov pib hauv qhov huv chloride electrolyte. Nws tsis hais dab tsi txog:
Crevice corrosion nyob rau hauv gaskets thiab deposits, qhov twg geometry thiab oxygen depletion dominate
Chloride stress corrosion cracking (SCC), qhov twg microstructure tseem ceeb tshaj li qhov sib xyaw ua ke
Sour service crackingRaws li NACE MR0175 / ISO 15156, qhov hardness thiab microstructural stability yog lub rooj vag
Caustic thiab muaj zog oxidizing kev pab cuam, qhov twg austenite thiab siab molybdenum coj txawv txawv ntawm ferrite
Ntev -lub sij hawm thermal stability, uas txiav txim siab seb koj cov khoom puas tseem nyob hauv spec tom qab 10 xyoo ntawm 60 degree
Mechanical Strength: Qhov twg Duplex yeej txiav txim siab
Qhov no yog ib cheeb tsam uas qhov kev sib piv tsis nyob ze. Annealed S32760 feem ntau xa tawm 0.2 feem pua cov pov thawj lub zog nyob ib ncig ntawm 550 MPa, tawm tsam kwv yees li 300 MPa rau S31254. Qhov ntawd yog ze rau ob npaug ntawm lub zog tawm los, nrog qhov kawg tensile qhov tseem ceeb nyob ib ncig ntawm 750-880 MPa rau duplex piv rau 655-690 MPa rau austenitic.
Cov tswv yim tsim nyog yog phab ntsa thickness. Rau qhov muab kev ntsuas siab thiab tus qauv tsim qauv-ASME B31.3, EN 13480, lossis PED- cov kev suav suav ua ke- cov yeeb nkab duplex lossis flange tuaj yeem teev muaj txiaj ntsig zoo dua. Hauv siab- khaws cov khoom siv rau hauv qab hiav txwv, sab saum toj, thiab siab- lub luag haujlwm ntawm cov txheej txheem siab, uas txhais ua:
- Tsawg tag nrho qhov hnyav, uas yog qhov tseem ceeb ntawm offshore platforms nrog kev siv nyiaj nruj heev
- Cov hnab ntawv me me flange (ASME B16.5, B16.47) qhov chaw nruj
- Txo lub hauv paus thiab txhawb nqa steel onshore
- Txo tus nqi thauj khoom ntawm qhov ntev - thauj khoom xa tawm mus rau Gulf lossis mus rau European chaw nres nkoj
Corrosion Resistance: Tsis Siv Lub Tshuab ntxhua khaub ncaws
Ntawm no yog qhov kev sib piv tsis yog lub rooj thiab dhau los ua tsob ntoo txiav txim.
Pitting kuj.ASTM G150 qhov ntsuas kub tseem ceeb rau kev daws teeb meem zoo -annealed cov ntaub ntawv av nyob rau hauv 70-80℃ntau yam rau ob qib, nrog S32760 feem ntau edging me ntsis ua tsaug rau nws cov nitrogen thiab tungsten. Nyob rau hauv huv, aerated seawater ntawm ambient kub, ob qho tib si tseem ceeb tiv thaiv pitting. Qhov sib cais tsuas yog tshwm nyob rau hauv kub, acidic, los yog chlorinated heev.
Kev txhim kho corrosion.Qhov ntsuas kub tseem ceeb ntawm ASTM G48 Txoj Kev F yuav zaum hauv 35-45℃ntau rau ob qho tib si. Qhov no yog hom kev ua tsis tiav uas tua cov dej hiav txwv, vim nws pib nyob rau hauv bolted flange ntsej muag, nyob rau hauv deposits, thiab nyob rau hauv marine kev loj hlob. S32760's tungsten pab ntawm no, tab sis qhov kev tiv thaiv tiag tiag yog tsim: kev nkag mus rau welds, du bore, tsis muaj threaded crevices, thiab cathodic tiv thaiv qhov twg spec tso cai.
Chloride stress corrosion cracking.Qhov no yog qhov uas cov qauv duplex khwv tau nws khaws cia. Austenitic stainless, txawm tias qib 6Mo, tuaj yeem tawg transgranularly hauv cov tshuaj chloride kub hauv qab tensile stress. Duplex qib tiv thaiv cov tshuaj chloride SCC zoo dua vim tias cov ferrite -austenite interface thaiv kev tawg tawg. Rau txhua yam uas khiav saum toj 60℃hauv chloride media nrog rau kev siv lossis kev ntxhov siab,S32760feem ntau yog qhov kev xaiv zoo dua metallurgical, txawm tias S31254 tseem zoo dua li 300-series austenitics.
Kev pabcuam qaub.Ob qib tshwm sim hauv NACE MR0175 / ISO 15156 rau cov roj thiab roj ib puag ncig uas muaj H2S, tab sis muaj kev txwv. Hardness yog capped (feem ntau 22 HRC rau S32760, nrog rau cov kev txwv zoo sib xws rau S31254 los ntawm cov neeg siv feem ntau), thiab cov khoom yuav tsum nyob rau hauv cov kev daws teeb meem -annealed mob uas tsis muaj kev ua hauj lwm txias tshaj qhov kev txwv. Rau Middle East qaub roj kev pab cuam -Saudi Arabia, UAE, Qatar, Kuwait- qhov no tsis yog{11}} sib tham, thiab daim ntawv pov thawj zeb yuav tsum tau hais txog kev kho cua sov kom meej.
Caustic thiab oxidizing media.Qhov no yog ib lub ces kaum uas S31254 nquag yeej. High -nickel austenitics tuav kub caustic, sulfuric acid, thiab oxidising chloride ib puag ncig zoo dua duplex, qhov twg ferrite theem yog qhov yooj yim. Pulp thiab ntawv, FGD cawv, thiab qee lub luag haujlwm petrochemical hauv Tebchaws Europe tseem qhia S31254 vim li no.
Vuam thiab Fabrication Realities
Vuam yog qhov uas ntau qhov kev txiav txim siab yuav khoom tiag tiag tau ua, vim tias tus nqi zog ntawm kev tau txais nws tsis ncaj ncees lawm dwarfs tus nqi sib txawv.
S32760 xav tau kev qhuab qhia.Thaum tshav kub kub tawm tswv yim yuav tsum nyob rau hauv lub qhov rais uas tau teev tseg - tsawg dhau thiab koj tau txais ntau tshaj ferrite thiab tsis zoo toughness, siab dhau lawm thiab koj yuav muaj feem cuam tshuam los nag lossis daus uas tiv thaiv corrosion. Interpass kub tswj yog yuav tsum tau, feem ntau tuav hauv qab 150 degree. Ib qho nitrogen-muaj cov roj rov qab yuav tsum tau khaws cia corrosion kuj ntawm cov hauv paus hniav, thiab tshaj -alloyed muab tub lim (feem ntau yog 6Mo los yog npib tsib xee-raws li consumable) yog teev kom them rau cov nitrogen poob. Theem tshuav nyiaj yuav tsum raug txheeb xyuas, feem ntau los ntawm kev ntsuas sib nqus, ntawm cov khoom kuaj cov khoom.
S31254 yog kev zam txim ntau dua tab sis tsis carefree.Cov qauv austenitic yog weldable nrog cov txheej txheem txheem, thiab qhov sib txuam 6Mo muab tub lim lossis ntau dua -alloyed npib tsib xee muab tub lim (xws li 625- hom) yog siv. Qhov txaus ntshai tiag tiag ntawm cov ntu hnyav yog sigma thiab chi theem nag lossis daus hauv tshav kub- thaj chaw cuam tshuam yog tias txias qeeb dhau -qhov no yog tib lub cuab uas ntes 904L thiab lwm yam siab -Mo austenitics. Ntu thickness saum toj no li ntawm 12-15 hli pib xav tau kev tswj cua txias los yog tom qab-weld tov anneal, uas ntxiv tus nqi thiab yuav distort fabricated sib dhos.
Tus Nqi Kev Lag Luam: Tshaj li tus nqi -Kilo
Hais ib qib stainless los ntawm kilo nqi nco feem ntau ntawm zaj dab neeg. Peb txheej txheej tus nqi txiav txim siab seb qib twg pheej yig dua rau txoj haujlwm.
1. Alloy surcharge volatility. S31254yog raug rau nickel thiab molybdenum kev lag luam. Nrog kwv yees li 18 feem pua nickel, txhua qhov nyiaj daus las txav ntawm LME nickel tus nqi hloov nws cov nqi ntxiv.S32760, nrog txog 7 feem pua nickel, tsis tshua muaj nickel tab sis raug ntau dua rau tungsten thiab chromium viav vias. Yog tias koj qhov project khiav hla ntau- lub hli qhov rais thiab koj daim ntawv cog lus tsis kaw cov nqi ntxiv, S31254 yog txoj kab nyiaj pheej hmoo dua.
2. Qhov hnyav txuag ntawm duplex.Lub 2x yield zog ntawm S32760 cia siab- ntsuam xyuas cov qauv poob phab ntsa thickness, feem ntau los ntawm 30-40 feem pua nyob ntawm cov cai thiab txoj kab uas hla. Ntawm qhov loj -dhau dej hiav txwv piping- feem ntau nyob rau hauv Gulf desalination thiab nyob rau hauv European cheeb tsam cua txias- qhov no tuaj yeem txiav cov tonnage txaus kom ntau tshaj li offset ntau dua ib -kilo duplex nqi. Peb tau pom cov xwm txheej uas S32760 tawm 15-25 feem pua pheej yig dua ntawm kev teeb tsa-tus nqi txawm tias raug nqi ntau dua ib kilo.
3. Fabrication thiab tshuaj xyuas tus nqi.Duplex welding qeeb qeeb, xav tau cov txheej txheem tsim nyog, ntau NDE, thiab nruj QA. Ntawm cov khoom me me lossis cov khoom siv nyuaj, tus nqi zog ntawd tuaj yeem tshem tawm qhov hnyav. Ntawm txoj kab ncaj nraim loj ntawm cov yeeb nkab lossis cov qauv flanged spools, qhov kev nplua tsim yog me me thiab duplex yeej.
HUITONG muab ob qib li cas
Raws li tus neeg muag khoom tau tsom mus rau siab - alloy stainless yeeb nkab, fittings, thiab flanges rau B2B export, HUITONG nqa ob leeg S31254 thiab S32760 hauv seamless thiab welded yeeb nkab, phaj, thiab bar, nrog flanges rau ASME B16.5 thiab fittings rau ASME B16.9 thiab B16.111. Cov khoom yog muab nrog EN 10204 3.1 lossis 3.2 MTCs raws li qhov yuav tsum tau ua, nrog rau kev ntsuas tshuaj lom neeg, kev siv tshuab, thiab kev xeb (ASTM G48 rau duplex, thiab ntawm kev thov rau 6Mo) qhia ib lub tshav kub.
Rau cov neeg yuav khoom, peb niaj hnub muab:
- Dual{0}} ntawv pov thawj qib uas chemistry sib tshooj (qee qhov cua sov ua tau raws li S31254 thiab 6Mo austenitic sib npaug)
- NACE MR0175 / ISO 15156 cov ntaub ntawv ua raws li kev pabcuam qaub
- PED 2014/68/EU conformity rau European siab khoom lub luag hauj lwm
- Kev cai ntev, bevelled xaus, thiab txiav - mus rau - loj phaj rau fabrication
- Thib peb-kev soj ntsuam tog (SGS, Bureau Veritas, TÜV, DNV) ntawm kev thov
Cov khoom lag luam muaj thiab tus nqi sib txawv nrog cov nickel thiab molybdenum kev lag luam, yog li peb hais cov nqi zeb tam sim no es tsis sau cov nqi teev npe - qhov no tseem ceeb tshwj xeeb tshaj yog rau S31254, qhov twg surcharge swings tuaj yeem txav tau ib nqe lus muaj txiaj ntsig rau ib lub lim tiam.
