Txhua tus kws tshaj lij cog ntoo tau saib 316L yeeb nkab ua tsis tiav hauv lub luag haujlwm uas cov ntaub ntawv hais tias yuav tsum ua haujlwm. Lub pitting pib ntawm ib qho kev sib txuas, los yog hauv qab lub gasket, los yog ntawm qhov chaw chloride stagnation, thiab nyob rau hauv ib lub caij cov kab yog to. Cov lus teb tus qauv yog txav mus rau ib qho kev sib tw - thiab rau feem ntau ntawm cov dej num, qhov tseeb tom ntej no tsis yog qib 6% molybdenum thiab nws tsis yog duplex.
Nws yog Alloy 904L, 4.5% molybdenum super austenitic stainless uas zaum ntawm 316 tsev neeg thiab 6Mo alloys, thiab uas nqa cov sulfuric acid, ntub phosphoric acid, thiab dej hiav txwv dej sov ua haujlwm uas kov yeej tus qauv austenitics.
Nplooj ntawv no cov ntaub ntawvAlloy 904L (UNS N08904, W.Nr 1.4539)- chemistry, cov khoom siv kho tshuab, lub hnab ntawv corrosion, thiab cov qauv tsim khoom siv rau 904L yeeb nkab thiab phaj.
904L yog dab tsi, thiab qhov twg nws zaum hauv tsev neeg stainless
luj 904lyog ib qho qis -carbon, siab- alloy austenitic stainless hlau nrog chemistry uas muab tso rau hauv "super austenitic" qeb: kwv yees li 23-28% nickel, 19-23% chromium, 4-5% molybdenum, thiab 1-2% tooj liab.
Cov tooj liab yog lub cim kos npe. Ua ke nrog cov molybdenum, tooj liab muab 904L nws txawv txawv rau sulfuric acid, vim tooj liab inhibits lub active dissolution ntawm cov hlau nyob rau hauv txo acid media.
Cov ntsiab lus npib tsib xee siab - ntau dua ob npaug ntawm 316L - muab cov hlau tsis muaj zog rau chloride kev nyuaj siab -corrosion tawg uas 316L tsuas tsis muaj. Qhov tshwm sim yog qib stainless uas tuav lub hnab ntawv dav corrosive yam tsis muaj tus nqi ntawm 6% molybdenum alloys lossis cov khoom txwv ntawm cov qib duplex.
Tshuaj muaj pes tsawg leeg rau ASTM B677
Cov cua sov- tsom xam txwv hauv qab no ua raws li ASTM B677 rau 904L seamless yeeb nkab (ASTM B625 specification npog phaj, thiab ASTM B673 npog welded yeeb nkab). Nickel yog 23.0-28.0%, thiab qhov sib npaug yog hlau.
| Element | Kev txwv kev txwv,% |
| Ni | 23.0 - 28.0 |
| Cr | 19.0 - 23.0 |
| Mo | 4.0 - 5.0 |
| Cu | 1.0 - 2.0 |
| C | 0.020 max |
| Mn | 2.0 max |
| Si | 1.0 max |
| P | 0.045 max |
| S | 0.035 max |
| N | 0.10 max |
Peb kab tsim nyog mloog. Cov pa roj carbon ntau tshaj ntawm 0.020% txhais tau hais tias cov hlau alloy tau muab rau hauv qhov qis - cov pa roj carbon monoxide, yog li nws tsis hnov qab thaum vuam thiab cua sov- thaj tsam cuam tshuam ua rau nws cov corrosion tsis kam tsis muaj kev daws teeb meem -anneal tom qab vuam - qhov txiav txim kom zoo dua hauv teb-fabricated pi
Cov kab tooj liab ntawm 1.0-2.0% yog cov khoom uas ua rau 904L excel nyob rau hauv sulfuric acid, vim tooj liab yog cov classic reducer ntawm corrosion tus nqi hauv kev txo cov kua qaub ib puag ncig. Cov kab npib tsib xee ntawm 23.0-28.0% yog dab tsi thawb cov hlau chloride SCC tsis kam nyob deb tshaj 316 tsev neeg: raws li cov ntsiab lus npib tsib xee nce siab tshaj li 20%, austenitic matrix ua rau muaj kev tiv thaiv ntau ntxiv rau chloride kev nyuaj siab-corrosion tawg.
Mechanical zog
ASTM B677 yuav tsum muaj cov nram qab no yam tsawg kawg nkaus tensile zog rau 904L seamless yeeb nkab nyob rau hauv cov kev daws teeb meem -annealed mob, uas yog tus txheej txheem xa khoom:
| Khoom | Yam tsawg kawg nkaus tus nqi (ASTM B677) |
| Tensile zog | 490 MPa (71 ksi) |
| Yield zog, 0.2% offset | 216 MPa (31 ksi) |
| Elongation | 35% |
904L yog austenitic alloy, uas txhais tau hais tias nws qhia cov txiaj ntsig ntawm austenitic: nws yog tag nrho tsis yog-sib nqus, nws khaws cov ductility thiab toughness mus rau qhov kub thiab txias, thiab nws yog weldable thiab formable nrog zoo tib yam austenitic stainless cov tswv yim. Nws lub zog yield yog piv rau 316L, yog li cov hlau tsis tau yuav rau lub zog - nws yog yuav rau corrosion kuj, thiab cov phab ntsa tsim yog teem los ntawm corrosion pub thiab pitting tsis kam es tsis yog los ntawm kev ntsuas siab.
Lub cev muaj zog
Qhov ceev ntawm 904L yog 8.0 g / cm³, thiab cov melting ntau yog kwv yees li 1300-1390 degree. Cov hlau muaj qhov hloov pauv ntawm elasticity ze ntawm 185 GPa ntawm chav tsev kub, me ntsis siab dua 316L vim yog cov nickel thiab molybdenum ntau ntxiv.
Nws cov thermal conductivity yog me ntsis qis dua tus qauv austenitics - txog 12.4 W / m·K ntawm 100℃- uas tseem ceeb hauv tshav kub-exchanger tsim qhov twg lub raj phab ntsa ua rau cov cua sov- hloov tsis kam.
Lub hnab ntawv corrosion: qhov twg 904L yeej txoj haujlwm
Cov ntaub ntawv lag luam rau 904L so ntawm peb lub luag haujlwm corrosion, thiab txhua tus yog cov ntaub ntawv tsis ua haujlwm ntawm 316 tsev neeg:
| Lub luag haujlwm | 904l ua | Vim li cas |
| Sulfuric acid, dilute mus rau nruab nrab concentration | Zoo heev | Copper + molybdenum inhibit active dissolution |
| ntub- txheej txheem phosphoric acid | Zoo heev | Cov txheej txheem cov khoom siv rau kev cog qoob loo |
| Chloride pitting thiab crevice corrosion | Zoo heev (PREN ~ 34) | 4-5% Mo nqa lub pitting tsis kam saum 316L |
| Chloride stress -corrosion cracking | Zoo tsis kam | 23-28% Ni txav cov hlau saum toj ntawm SCC qhov pib |
| Seawater, ambient mus rau nruab nrab kub | Zoo nrog kev saib xyuas | Zoo tshaj 316L; 6Mo qib tseem zoo dua hauv dej hiav txwv sov |
| Nitric acid thiab muaj zog oxidizing media | Nruab nrab | Tsis yog alloy lub luag haujlwm tseem ceeb |
Rau tus neeg yuav khoom txoj kab kev ua tau zoo yog qhov no: qhov twg 316L tau ua tsis tiav lossis yog qhov tsis zoo hauv kev pabcuam sulfuric lossis phosphoric acid, hauv cov dej sov chloride, lossis hauv SCC- qhov chaw nkag siab, 904L yog tus nqi- nce qib.
Nws muab feem ntau ntawm cov txiaj ntsig corrosion ntawm 6% molybdenum alloys ntawm qhov txo qis ntawm cov hlau ntxiv, thiab nws ua li ntawd hauv cov qauv austenitic tag nrho uas welds thiab cov ntaub ntawv zoo li tus qauv stainless. Cov ntaub ntawv ciam teb yog cov dej hiav txwv sov tsis tu ncua: 904L ua tau zoo tab sis tsis yog qhov kev xaiv zoo tshaj plaws nyob rau ntawd, thiab tus kws tsim qauv tsim yuav tsum nce mus rau qib 6Mo lossis nickel alloy rau lub luag haujlwm ntawd.
Cov qauv tsim khoom thiab cov qauv tsim khoom
904L yog muab los ntawm cov kev qhia hauv qab no, xaiv los ntawm cov khoom lag luam:
- ASTM B677 / ASME SB -677 - seamless yeeb nkab
- ASTM B673 / ASME SB -673 - welded yeeb nkab
- ASTM B625 / ASME SB -625 - phaj, ntawv, thiab sawb
- ASTM B649 / ASME SB -649 - bar thiab forgings
- EN 10216-5 / EN 10217-7 - European sib npaug (1.4539)
Vim hais tias 904L yog austenitic alloy tag nrho, txoj kev tsim khoom tsom iav 316L: cov yeeb nkab yog kub pierced los yog dov, ces tov annealed thiab quenched, nrog lub anneal kub feem ntau nyob rau hauv lub 1090-1175℃ntau yam.
Cov ntsiab lus tsis tshua muaj carbon yog khaws cia los ntawm cov yaj, thiab cov khoom tiav tau muab nkag rau hauv annealed, pickled, thiab passivated mob. ASTM B677 seamless yeeb nkab yog muaj nyob rau hauv tag nrho cov qauv thiab kev cai qhov ntev, thiab cov phaj ib B625 yog muab nyob rau hauv thicknesses los ntawm nyias daim ntawv mus rau hnyav phaj rau nkoj tsim.
Tej kev siv
luj 904ltau teev tseg hauv cov kev pabcuam hauv qab no:
- Sulfuric acid ntau lawm thiab tuav cov kab, nrog rau cov dilution thiab cia tshuab
- ntub- txheej txheem phosphoric acid nroj tsuag - evaporators, hloov kab, thiab reactor internals
- Seawater cooling systems thiab heat exchangers qhov twg 316L yog marginal
- Cov txheej txheem tshuaj cov nroj tsuag tuav cov chlorides sib xyaw thiab txo cov kua qaub
- Pulp thiab ntawv bleach nroj tsuag
- Pharmaceutical thiab nplua - cov khoom siv tshuaj uas cov khoom purity tsav cov khoom xaiv
Nyob rau hauv txhua qhov kev pab cuam qhov tshwj xeeb yog tsav los ntawm cov ntaub ntawv tsis ua tiav ntawm qib qis, thiab 904L raug xaiv vim tias nws kaw qhov sib txawv yam tsis muaj kev nplua nplua ntawm duplex lossis tus nqi ntawm 6Mo thiab npib tsib xee alloys. Rau lub nkoj thiab lub tank tsim, 904L phaj yog tus qauv specification rau sulfuric acid cia, thiab rau piping seamless B677 khoom yog lub neej ntawd rau cov txheej txheem kab.
Vuam thiab fabrication
904L welds nrog tib lub khw kev coj ua raws li 316L: GTAW thiab GMAW nrog cov muab tub lim zoo sib xws, tsis tas yuav tsum tau ua ntej, thiab tsis muaj kev tshaj tawm - vuam cua sov ib txwm xav tau vim tias cov ntsiab lus carbon tsawg tiv thaiv kev nkag siab.
Matching muab tub lim hlau rau AWS A5.9 ERNiCrMo-3 (625-hom muab tub lim) los yog 904L muab tub lim tshwj xeeb feem ntau yog siv los ua kom haum rau corrosion kuj nyob rau hauv cov hlau weld, thiab qhov twg daim ntawv thov xav tau, lub weld yog tsim nrog ib tug nickel-raws li muab tub lim los lav lub pitting tsis kam ntawm lub sib koom tes.
Lub alloy yog tag nrho austenitic, yog li nws yog rhiab heev rau kub tawg yog hais tias lub weld yog ua los ntawm cov cua kub ntau dhau - tus qauv austenitic xyaum ntawm kev tswj interpass kub thiab tsawg tshav kub input siv. Txias txoj kev yog ncaj nraim nrog cov txheej txheem stainless tooling, thiab cov hlau ua haujlwm - hardening tus nqi yog nruab nrab.
Yuav ua li cas qhia rau ntawm qhov kev txiav txim
Yuav kom tau txais kev xa khoom huv 904L, qhov kev nug yuav tsum hais cov hauv qab no:
- Txheem thiab daim ntawv: "seamless yeeb nkab rau ASTM B677", "phaj rau ASTM B625", UNS N08904 / 1.4539
- Qhov loj me hauv qhov system raug: NPS + lub sijhawm rau cov yeeb nkab, OD x phab ntsa lossis thickness x dav x ntev rau phaj
- Cov xwm txheej: tshuaj annealed, pickled, passivated
- Daim ntawv pov thawj: EN 10204 3.1, nrog PMI thiab qhov yuav tsum tau kuaj xyuas
FAQ
Q: Puas yog 904L yog duplex stainless hlau?
A: Tsis yog . 904L yog tag nrho austenitic nrog lub ntsej muag -centred- cubic qauv, zoo li 316L. Nws nqa nickel thiab molybdenum siab dua 316L, tab sis nws tsis yog qib duplex thiab tsis muaj ob -theem qauv ntawm 2205 lossis 2507.
Q: Dab tsi yog 904L siv rau?
A: Feem ntau rau sulfuric acid, ntub - txheej txheem phosphoric acid, thiab sov chloride kev pab cuam qhov twg 316L tsis ua hauj lwm los ntawm pitting, crevice corrosion, los yog chloride stressing -corrosion cracking. Nws yog feem ntau hauv cov nroj tsuag chiv, acid tuav, thiab seawater txias tshuab.
Q: PREN ntawm 904L yog dab tsi?
A: Kwv yees li ntawm 34, xam los ntawm 19-23% chromium, 4-5% molybdenum, thiab txog li 0.10% nitrogen. Qhov no zoo tshaj 316L (kwv yees 24) thiab qis dua qib 6Mo (kwv yees 41-44).
Q: Puas yog 904L tiv thaiv kev ntxhov siab chloride-corrosion tawg?
A: Yog, zoo tshaj 316L. Cov ntsiab lus 23-28% npib tsib xee tso lub austenitic matrix saum toj ntawm SCC qhov kev nkag siab ntawm qhov chaw rau feem ntau cov chloride ib puag ncig, txawm hais tias nws tsis muaj kev tiv thaiv nyob rau hauv cov mob hnyav tshaj plaws.
Q: 904L puas tuaj yeem welded yam tsis muaj kev tshaj tawm -weld kev kho cua sov?
A: Yog. 0.020% siab tshaj cov ntsiab lus carbon tiv thaiv carbide rhiab heev nyob rau hauv lub tshav kub- cuam tshuam cheeb tsam, yog li ntawd lub as-welded ob leeg khaws nws corrosion kuj. Kev sib tw los yog npib tsib xee-raws li muab tub lim yog siv los ua kom haum cov vuam- hlau ua haujlwm.
Q: Qhov txawv ntawm 904L thiab 254SMO yog dab tsi?
A: 254SMO yog 6% molybdenum qib (UNS S31254) nrog cov pitting ntau dua thiab muaj zog dua, npaj rau cov dej hiav txwv sov thiab cov chlorides txhoj puab heev . 904L (4-5% Mo) tsis tshua kim thiab ua tau zoo hauv sulfuric thiab phosphoric acid lub luag haujlwm. Kev xaiv yog tsim los ntawm qhov nruab nrab: cov ntsiab lus acid rau 904L, cov ntsiab lus dej hiav txwv sov rau 6Mo.
