Q1: Nyob rau hauv lub ntiaj teb no ntawm high- alloy austenitic stainless hlau, feem ntau tsis meej pem ntawm 904L thiab 1.4507. Dab tsi yog qhov kev txhais cov ntsiab lus thiab kev ua tau zoo hloov kho uas 1.4507 muab tshaj nws cov thawj coj?
A: Thaum Alloy 1.4507 (UNS N08028) feem ntau yog pab pawg nrog super austenitics zoo li 904L, nws sawv cev rau kev dhia tseem ceeb hauv kev tsim metallurgical, tshwj xeeb tshaj yog optimized rau feem ntau aggressive acid ib puag ncig.
Lub ntsiab lus hloov kho yog nyob rau hauv nws cov ntsiab lus Molybdenum thiab Nitrogen, ua ke nrog kev tswj hwm ntawm tooj liab.
Compositional Shift: 1.4507 feem ntau muaj nyob ib ncig ntawm 3.5% Molybdenum thiab 1.5% tooj liab. Qhov no yog siab dua tus qauv 316L thiab muaj kev sib npaug sib npaug piv rau 904L.
Kev Txhim Kho Kev Ua Haujlwm: Qhov kev sib xyaw tshwj xeeb no tau tsim los ntawm Sandvik (thawj li Sanicro 28) los daws ob qhov kev hem thawj ib txhij:
Txo cov kua qaub: Cov ntsiab lus Molybdenum siab muab qhov tshwj xeeb tiv thaiv kom txo cov kua qaub xws li sulfuric thiab phosphoric acid.
Oxidizing tej yam kev mob: Cov tooj liab ntxiv ho txhim khu kev tiv thaiv oxidizing xov xwm feem ntau pom nyob rau hauv acid circuits.
Qhov tshwm sim yog cov khoom uas zaum hauv "qhov chaw qab zib." Nws muaj kev tiv thaiv corrosion uas txuas qhov sib txawv ntawm cov qauv stainless hlau thiab siab -kawg nickel alloys zoo li C-276, tab sis ntawm tus nqi qis dua. Rau cov kav dej hauv cov txheej txheem ntub dej phosphoric acid (WPA) cov nroj tsuag, 1.4507 tau dhau los ua tus qauv de facto vim nws tiv taus cov gypsum slurry thiab cov kua qaub sib tov uas sai sai degrade 316L.
Q2: Peb tab tom tsim cov kav dej rau chav tsev tshiab phosphoric acid evaporator. Vim li cas 1.4507 yeeb nkab feem ntau yog "cov ntaub ntawv hauv paus" rau cov kev pabcuam no, thiab qhov twg yog qhov txwv tsis pub tshaj?
A: Hauv kev lag luam phosphoric acid, tshwj xeeb tshaj yog cov txheej txheem "dihydrate" rau kev tsim cov chiv, 1.4507 (Sanicro 28) yog suav tias yog cov khoom siv ua haujlwm. Nws txoj kev xaiv yog ua raws li kev nkag siab tob txog cov txheej txheem kev txhim kho corrosion hauv zos.
Yog vim li cas nws excel:
Phosphoric acid uas tsim los ntawm cov txheej txheem ntub dej muaj impurities xws li chlorides, fluorides, thiab silica. Cov impurities no tsim ib qho chaw nruj heev uas tawm tsam tus qauv stainless hlau hauv ob txoj hauv kev:
General Corrosion: Cov kua qaub nws tus kheej dissolves lub passive txheej.
Crevice Corrosion: Nyob rau hauv deposits ntawm gypsum (scale), chlorides concentrate, ua rau pitting sai.
Lub siab Molybdenum (Mo) thiab Nitrogen (N) hauv 1.4507 muab qhov siab Pitting Resistance Equivalent Number (PREN), feem ntau nyob ib ncig ntawm 38-40. Qhov siab PREN tus nqi no txhais tau hais tias cov oxide txheej ruaj khov thiab tiv taus cov tshuaj chloride nres, txawm tias nyob rau hauv qhov chaw tso nyiaj. Cov ntsiab lus tooj liab kuj tshwj xeeb inhibits corrosion hauv cov ntshiab phosphoric acid media.
Cov Limits (Qhov twg nws ua tsis tau):
Kub Ceiling: Nyob rau hauv phosphoric acid, raws li kub tshaj 120 ° C (250 ° F), tus nqi corrosion ntawm 1.4507 tuaj yeem nce sharply. Rau reactor coolers lossis evaporators ua haujlwm ntawm qhov kub siab dua, engineers yuav tsum tau hloov mus rau ntau dua nickel alloy xws li 625 lossis C-276.
Hydrofluoric Acid (HF): Yog tias cov pob zeb phosphate siv muaj cov tshuaj fluoride / chloride siab heev, kev tsim cov hydrofluoric acid tuaj yeem ua phem rau cov silicon thiab chromium hauv 1.4507. Nyob rau hauv xws li mob, txawm 1.4507 tej zaum yuav raug kev txom nyem, yuav tsum tau ib tug sib txawv alloy tswv yim.
Q3: Peb yuav tsum tau vuam 1.4507 yeeb nkab rau tus qauv 316L stainless hlau flange vim muaj kev txwv. Puas yog qhov no metallurgically muaj kev nyab xeeb, thiab cov hlau muab tub lim yuav tsum tau teev tseg los tiv thaiv tsis ua haujlwm?
A: Qhov no yog ib qho kev sib tw-kev tsim khoom, tab sis nws yuav tsum tau ua tib zoo xav. Vuam sib txawv ntawm cov hlau zoo li 1.4507 thiab 316L yog ua tau, tab sis nws tsim ib qho kev sib txuas ntawm galvanic thiab metallurgical uas yuav tsum tau tswj kom raug.
Qhov Risk:
Yog tias koj siv tus qauv 316L muab tub lim hlau, thaj chaw weld dilution yuav muaj qhov sib xyaw ntawm ob lub hauv paus hlau. Qhov no diluted cheeb tsam yuav tsis muaj lub siab Molybdenum thiab Nickel cov ntsiab lus ntawm 1.4507, tsim kom muaj qhov "tsis muaj zog txuas" uas muaj kev cuam tshuam rau qhov kev nyiam tshaj plaws corrosion nyob rau hauv ib puag ncig koj tau nruab 1.4507 los tiv thaiv.
Kev daws:
Koj yuav tsum siv ntau tshaj -alloyed filler hlau.
Pom zoo Filler: ERNiCrMo-3 (Alloy 625) yog tus qauv kev lag luam rau kev sib koom tes no.
Vim li cas: Lub 625 muab tub lim muaj cov ntsiab lus siab nickel thiab molybdenum. Txawm tias thaum diluted los ntawm 316L ntawm ib sab thiab 1.4507 ntawm qhov tod tes, qhov tshwm sim ntawm cov nyiaj tso nyiaj tseem tshuav ntau dua - sib npaug ntawm kev tiv thaiv corrosion. Nws ua raws li qhov tsis muaj, kom ntseeg tau tias qhov vuam nws tus kheej tsis dhau los ua qhov tsis ua haujlwm.
Lus Cim Tseem Ceeb: Paub txog qhov sib txawv ntawm qhov sib txawv ntawm thermal expansion . 1.4507 thiab 316L muaj cov coefficients zoo sib xws ntawm thermal expansion, yog li thermal qaug zog tsis tshua muaj kev txhawj xeeb tshaj qhov kev pheej hmoo corrosion, tab sis cov txheej txheem weld yuav tsum tseem txo cov cua sov tawm.
Q4: Tshaj li kev lag luam tshuaj chiv, nyob rau hauv lwm qhov tseem ceeb ntawm kev lag luam tawm thiab dej hiav txwv yog 1.4507 yeeb nkab tau teev tseg, thiab cov cuab yeej tshwj xeeb twg ua rau nws tsim nyog rau cov cheeb tsam ntawd?
A: 1.4507 muaj nuj nqis heev hauv kev lag luam roj thiab roj av, tshwj xeeb rau kev tuav dej hiav txwv thiab kev pabcuam qaub (H₂S ib puag ncig).
1. Seawater Piping (Cov kab hluav taws xob thiab cov kav dej txias):
Qhov Kev Sib Tw: Cov ntaub ntawv txheem zoo li tooj liab-nickel (90/10 lossis 70/30) lossis 316L stainless hlau muaj qhov cuam tshuam rau kev yaig-corrosion thiab microbiologically cuam tshuam corrosion (MIC) nyob rau hauv siab -ceev seawater. 316L yog tshwj xeeb tshaj yog nyob rau hauv corrosion.
Qhov zoo ntawm 1.4507: Qhov siab PREN tus nqi (38-40) ntawm 1.4507 muab kev tiv thaiv zoo heev rau crevice corrosion hauv dej hiav txwv ambient. Qhov no tso cai rau cov txheej txheem phab ntsa nyias nyias thiab cov qauv tsim siab dua piv rau 316L, ua rau cov kav dej sib zog thiab ua haujlwm zoo dua rau cov qauv sab saum toj ntawm lub platform.
2. Cov Kab Ntsig Nroj Tsuag (Upstream):
Qhov Kev Sib Tw: Cov kav dej nqa cov roj nrog cov ntsiab lus tseem ceeb ntawm Hydrogen Sulfide (H₂S) thiab chlorides yog qhov pheej hmoo ntawm Sulfide Stress Cracking (SSC).
Qhov zoo ntawm 1.4507: Txawm hais tias tsis muaj zog ntau npaum li cov Nickel alloys siab heev -raws li C-series alloys, 1.4507 muaj kev tiv thaiv siab rau SSC nyob rau hauv ib puag ncig qaub qaub (mus txog ib feem ntawm qhov siab ntawm H₂S). Nws yog feem ntau teev raws li "corrosion resistant alloy" (CRA) clad hauv ob sab phlu rau carbon steel kav, muab tus nqi -zoo barrier tiv thaiv qaub kev pab cuam corrosion tsis xav tau ib tug khoom phab ntsa ntawm kim alloy.
Q5: Dab tsi yog qhov tseem ceeb rau kev khoov thiab txias ua 1.4507 yeeb nkab piv rau cov qauv austenitic stainless hlau zoo li 304/316?
A: Khoov 1.4507 yeeb nkab yuav tsum muaj zog ntau dua thiab muaj kev pheej hmoo siab ntawm lub caij nplooj ntoos hlav- rov qab thiab tawg dua li khoov 304/316. Qhov no yog vim nws lub zog tawm los ntau dua thiab ua haujlwm sai- tus nqi hardening.
Cov ntsiab lus tseem ceeb rau Fabricators:
Siab zog yuav tsum tau:
1.4507 muaj lub zog tawm los ntau dua 316L (feem ntau 50-60% siab dua nyob rau hauv cov mob annealed). Rotary draw benders lossis induction benders yuav tsum muaj peev xwm txaus torque. Kev kwv yees qhov no tuaj yeem ua rau buckling lossis tsis tiav khoov.
Ua Haujlwm Hardening:
Raws li cov yeeb nkab yog khoov, cov khoom ua hauj lwm hardens sai heev. Yog tias koj sim rov- khoov lossis kho qhov khoov, cov khoom yuav tawg vim nws poob nws qhov ductility. Kev khoov yuav tsum yog ib qho - kev txhaj tshuaj ua tiav thawj zaug.
Caij nplooj ntoos hlav-Kev them nyiaj rov qab:
Vim nws lub zog siab, 1.4507 nthuav tawm ntau lub caij nplooj ntoos hlav- rov qab dua 316L. Cov cuab yeej yuav tsum tau teem rau tshaj - khoov (feem ntau 5-10% ntau tshaj lub hom phiaj lub kaum sab xis) kom ua tiav lub kaum sab xis kawg tom qab lub siab tso tawm.
Mandrel thiab Wiper Tuag Xaiv:
Vim hais tias cov khoom yog "gummier" thiab tougher, tooling yuav tsum nyob rau hauv zoo heev mob. Ib tug khawb mandrel tuaj yeem tso rau sab hauv ntawm cov yeeb nkab, ua rau cov qhab nia uas ua rau muaj kev ntxhov siab thiab qhov chaw muaj peev xwm corrosion. Siv hnyav-lub luag haujlwm lubricants tshwj xeeb tsim rau siab- alloy steels los tiv thaiv galling.
Ncej - Khoov Kub Khov (Kev daws teeb meem Annealing):
Hnyav dabtsi yog khoov induces siab residual stresses thiab ib tug deformed grain qauv. Rau kev khoov hnyav rau cov kev pabcuam corrosive heev (tshwj xeeb tshaj yog nyob rau sab ntug dej hiav txwv lossis cov kua qaub ib puag ncig), kev tshaj tawm - khoov tshuaj anneal thiab quench yuav tsum tau los kho cov khoom siv tag nrho corrosion- tiv thaiv microstructure. Qhov no yog ib kauj ruam kim tab sis qee zaum yuav tsum tau ua raws li tus qauv tsim qauv.
