1. Dab tsi yog qhov tseem ceeb ntawm kev txhim kho metallurgical hauv Hastelloy B-2 (UNS N10665) dhau ntawm tus thawj Hastelloy B, thiab vim li cas cov no tseem ceeb rau kev siv cov kav dej txias?
Hastelloy B-2 sawv cev rau qhov kev hloov pauv tseem ceeb los ntawm Hastelloy B (UNS N10001), tshwj xeeb yog tsim los kom kov yeej cov khoom qub uas tsis muaj zog tshaj plaws: thermal instability ua rau weld thiab tshav kub-tshem tawm tsam (HAZ) rhiab heev.
Cov kev txhim kho tseem ceeb yog cov tshuaj ua kom zoo tshaj plaws uas ua kom muaj kev ruaj ntseg microstructural:
Kev txo qis ntawm Hlau thiab Chromium: B-2 nruj me ntsis txo cov ntsiab lus no (Fe Tsawg dua lossis sib npaug rau 2.0%, Cr Tsawg dua lossis sib npaug li 1.0% piv rau qib siab dua hauv B). Nyob rau hauv thawj B alloy, hlau thiab chromium, nrog rau carbon thiab silicon, txhawb cov nag lossis daus ntawm intermetallic theem (xws li Ni₄Mo, μ-theem, thiab carbides) thaum raug kub nyob rau hauv 600-1200℃(1110-2190℃F) ntau. Cov precipitates no tsim tshwj xeeb ntawm cov ciam teb nplej, tsim cov cheeb tsam uas muaj anodic thiab raug rau kev cuam tshuam loj heev hauv cov xov xwm corrosive.
Ultra-Cov pa roj carbon tsawg thiab Silicon: B-2 qhia qhov siab tshaj plaws rau cov pa roj carbon ntau (tsawg dua lossis sib npaug li 0.010%) thiab silicon (tsawg dua lossis sib npaug li 0.10%). Qhov no ntxiv suppresses tsim ntawm detrimental carbide thiab silicide networks.
Criticality rau Cold Drawn Pipe:
Rau cov kav dej txias, cov kev txhim kho no yog qhov tseem ceeb rau ob qho laj thawj:
Ncej -Kaw Kev Nyuaj Siab: Kev kos duab txias ua rau muaj kev ntxhov siab tseem ceeb. Ib qho qis - qhov kub thiab txias kev ntxhov siab anneal (feem ntau nyob ib ncig ntawm 885℃/ 1625℃F) feem ntau yog siv rau B-2 kav dej kom rov qab muaj qhov ruaj khov thiab tiv thaiv kev ntxhov siab corrosion tawg. Tus thawj B alloy yuav ua rau muaj kev puas tsuaj loj ntawm qhov kub thiab txias, rhuav tshem nws cov corrosion kuj. B-2 nyob ruaj khov.
Weld Integrity: Txhua lub kav dej yuav tsum tau vuam. B-2's ruaj khov chemistry kom ntseeg tau tias HAZ nyob ib sab rau welds khaws cov corrosion kuj ze li ntawm cov niam txiv hlau, tshem tawm "riam-kab nres" uas plagued welded Hastelloy B systems. Qhov no ua rau B-2 cov yeeb nkab tshuab hauv paus txhim khu kev qha thiab fabricable.
2. Nyob rau hauv dab tsi tshwj xeeb, kev siv tshuaj lom neeg hnyav yog Hastelloy B-2 cov kav dej txias uas tsim nyog, thiab vim li cas cov txheej txheem txias rub tau zoo?
Hastelloy B-2 yog cov khoom siv hluav taws xob zoo tshaj plaws rau kev tswj cov kev ua phem tshaj plaws uas txo cov kua qaub, tshwj xeeb tshaj yog qhov kub thiab txias, concentration, thiab tsis muaj oxidizing agents.
Cov ntawv thov tseem ceeb:
Hydrochloric Acid (HCl) Qhuav & Kuaj: Qhov no yog daim ntawv thov tseeb. B-2 kav dej yog siv rau reactor effluent kab, reboiler loops, thiab hloov kab rau kub, concentrated, thiab feem ntau anhydrous HCl. Lawv tiv taus tag nrho cov concentrations mus txog rau lub boiling point.
Acetic Acid thiab Anhydride Ntau Lawm: Tshwj xeeb tshaj yog nyob rau hauv cov txheej txheem xws li Monsanto lossis Cativa cov txheej txheem, qhov twg cov tshuaj tiv thaiv ib puag ncig txo thiab tuaj yeem muaj halide impurities.
Sulfuric Acid ntawm High Concentration & Kub: Thaum tsis yog rau tag nrho cov concentrations, B-2 ua tau zoo nyob rau hauv concentrated sulfuric acid (Ntau tshaj los yog sib npaug rau 90%) ntawm qhov kub siab nyob rau hauv nruj me ntsis txo cov kev mob.
Alkylation & Isomerization Units (Tshuaj, tsis yog Petrochemical): Tuav aggressive catalysts zoo li txhuas chloride (AlCl₃) nyob rau hauv hydrocarbon kwj.
Cov txiaj ntsig ntawm Cold Drawn Process rau Cov Kev Pab Cuam no:
Superior Surface Finish: Kev kos duab txias ua rau cov yeeb nkab uas muaj qhov sib luag, zoo ib yam sab hauv. Qhov no txo qis cov cheeb tsam uas cov corrosives tuaj yeem ua pas dej lossis cov khoom khib nyiab tuaj yeem tso, txo cov kev pheej hmoo ntawm qis dua - tso nyiaj corrosion thiab yaig-corrosion nyob rau hauv siab - nrawm nrawm.
Txhim kho Mechanical Properties: Kev ua haujlwm txias ua rau muaj txiaj ntsig zoo thiab lub zog tensile ntawm cov yeeb nkab piv rau cov mob annealed. Qhov no tso cai rau kev siv cov phab ntsa nyias (xws li, Teem sijhawm 10S, 40S) thaum tswj kev ntsuas siab, muab cov khoom siv nyiaj txuag thiab txo qhov hnyav.
Dimensional Precision: Kev kos duab txias muab kev tswj xyuas zoo tshaj OD, ID, thiab phab ntsa thickness kam rau ua. Qhov no yog qhov tseem ceeb rau kev sib dhos ua ke, ua kom muaj kev sib dhos zoo, thiab tswj xyuas cov yam ntxwv zoo ib yam hauv cov txheej txheem txheej txheem.
3. Dab tsi yog qhov tseem ceeb welding thiab fabrication raws tu qauv rau Hastelloy B-2 txias drawn yeeb nkab kom khaws nws corrosion kuj nyob rau hauv raws li welded tej yam kev mob?
Thaum B-2 muaj ntau yam weldable ntau dua li nws cov neeg ua ntej, nws tseem yog ib qho tshwj xeeb alloy uas yuav tsum tau ua cov txheej txheem nruj kom tsis txhob qhia qhov tsis muaj zog.
Vuam txheej txheem: Gas Tungsten Arc Vuam (GTAW/TIG) yog yuav tsum tau rau hauv paus thiab kub dhau. Nws qhov kev tswj xyuas kom sov yog qhov tseem ceeb. Shielded Hlau Arc Vuam (SMAW) nrog cov khoom siv electrodes tuaj yeem siv rau cov ntawv sau rau ntawm phab ntsa tuab.
Filler Hlau: ERNiMo-7 (Hastelloy B-2 muab tub lim) lossis ERNiMo-10 (Hastelloy B-3 muab tub lim) yuav tsum tau siv. Siv cov khoom siv tsis sib xws (piv txwv li, ib hom nickel-chromium) yuav tsim cov galvanic cell thiab ua rau kom ceev, xaiv corrosion ntawm cov vuam los yog HAZ.
Qhov tseem ceeb Parameter: Ultra-Cov Cuab Yeej Cuab Yeej Tsawg: Qhov no yog ib txoj cai tseem ceeb tshaj plaws. Kev siv hluav taws xob siab tuaj yeem ua rau muaj kev sib cais me me. Siv:
Tsawg amperage.
Kev kub ceev mus txawv tebchaws.
Cov txheej txheem nqaim hlaws (tsis muaj weaving).
Kev tswj qhov kub thiab txias, feem ntau Tsawg dua lossis sib npaug li 120℃(250℃F). Kev siv qhov kub thiab txias - qhia cov crayons yog tus qauv.
Kev Tsim Kho & Kev Tu Kom Huv: Siv qhov nruj, zoo ib yam -up (qhov sib txawv hauv paus qis). Txhua qhov chaw yuav tsum tau ua tib zoo ntxuav cov roj, roj, av, thiab cov cim cim (uas feem ntau muaj cov tshuaj chlorides lossis sulfur). Dedicated, uncontaminated stainless hlau hlau txhuam yuav tsum tau siv los ntxuav.
Tshaj tawm -Kev kho cua sov (PWHT): Tsis zoo li qub B alloy, B-2 tsis xav tau PWHT rau kev tiv thaiv corrosion hauv feem ntau cov ntawv thov. Nws stability tso cai rau nws siv nyob rau hauv lub as-welded mob. Txawm li cas los xij, rau cov kev pabcuam cuam tshuam nrog cov tshuaj caustics lossis kub hydrofluoric acid, tag nrho cov tshuaj anneal (1070-1120℃/ 1960-2050℃F, dej quench) yuav raug teev tseg kom rov qab tau qhov siab tshaj plaws ductility thiab corrosion kuj, tshwj xeeb tshaj yog rau cov ntu tuab.
4. Yuav ua li cas yog cov thawj corrosion tsis ua hauj lwm hom uas tseem tuaj yeem cuam tshuam rau Hastelloy B-2 piping systems, thiab lawv yuav txo tau li cas los ntawm kev tsim thiab kev ua haujlwm?
Tsis muaj cov khoom siv tiv thaiv kab mob rau txhua hom kev degradation. Nkag siab txog B-2 cov kev txwv yog qhov tseem ceeb rau nws daim ntawv thov ua tiav.
1. Ceev Oxidizing Attack (Musapplication): Feem ntau thiab tsis ua hauj lwm hnyav. B-2 tsis muaj kev zam rau oxidizing tus neeg sawv cev. Kev taw qhia txog cov pa oxygen, nitric acid, ferric (Fe³⁺) lossis cupric (Cu²⁺) ions, chlorine, lossis hydrogen peroxide yuav ua rau muaj kev kub ntxhov, kev xeb.
Mitigation: Cov txheej txheem tsis raug tswj xyuas kom muaj kev txo qis ib puag ncig. Siv cov pa oxygen scavengers. Txhim kho rupture disks los yog cov vents tshwj xeeb los tiv thaiv huab cua nkag. Tsis txhob siv B-2 yog tias muaj oxidant tuaj yeem ua tau; hloov mus rau chromium-muaj alloy xws li Hastelloy C-276.
2. Stress Corrosion Cracking (SCC) nyob rau hauv Kub Caustics: Thaum resistant rau chloride-SCC, B-2 yog raug rau caustic cracking (caustic embrittlement) nyob rau hauv concentrated sodium/potassium hydroxide daws saum toj no kwv yees li 120℃(250℃F), tshwj xeeb tshaj yog nyob rau hauv residual tensile stress
Mitigation: Tsis txhob siv rau hauv kub, concentrated caustic kev pab cuam. Yog tias tsis tuaj yeem zam tau, qhia tag nrho cov tshuaj anneal rau ntawm qhov kev ua tiav kom txo qis cov kev ntxhov siab los ntawm kev tsim thiab kos duab txias.
3. Localized Attack at Imperfections: Thaum lub qhov txias rub saum npoo yog du, txhua yam khoom tsis xws luag (ib qho sib sib zog nqus khawb, ua tsis zoo, los yog cov khoom siv embedded ferrous los ntawm cov cuab yeej) tuaj yeem tsim qhov chaw pib ntawm pitting lossis crevice corrosion.
Kev txo qis: kev tuav ceev, siv cov cuab yeej tshwj xeeb, thiab cov txheej txheem vuam kom raug. Tom qab- kev tu vaj tse (pickling / passivation nrog HNO₃ / HF cov khoom sib xyaw yog tus qauv rau cov nickel alloys) feem ntau tau teev tseg kom tshem tawm cov paug paug thiab ua kom cov txheej txheem tsis zoo.
5. Los ntawm kev xav txog tus nqi ntawm lub neej, thaum twg qhov kev qhia tshwj xeeb Hastelloy B-2 cov yeeb nkab txias txias dhau los ua kev lag luam ncaj ncees rau ntau cov alloys xws li 316L lossis ntau dua-nickel alloys xws li C-276?
Qhov kev txiav txim siab yog qhov xwm txheej classic ntawm "haum-rau- lub hom phiaj" kev xaiv uas tau tsav los ntawm ib puag ncig tshuaj lom neeg, tsis yog los ntawm tus nqi pib ib leeg.
vs. 316L/317L Stainless Hlau: Cov no yog cov xaj ntawm qhov loj dua pheej yig dua. Txawm li cas los xij, lawv tsis muaj txiaj ntsig nyob rau hauv kub, concentrated hydrochloric acid lossis lwm cov kua qaub txo qis heev -lawv yuav corrode sai. Kev suav nyiaj txiag yog qhov yooj yim: yog tias cov txheej txheem dej nyob hauv B-2 lub npe, stainless hlau tsis yog ib qho kev xaiv. Tus nqi ntawm ib qho tsis ua haujlwm (lub sijhawm poob qis, cov khoom poob, qhov xwm txheej kev nyab xeeb) dwarfs tus nqi ntawm B-2.
vs. Hastelloy C-276/C22: Cov no yog cov "universal" corrosion-resistant alloys thiab kim dua B-2. Lawv muaj chromium thiab tuaj yeem ua rau ob qho tib si oxidizing thiab txo cov mob.
Qhia meej B-2 thaum: Ib puag ncig tau lees paub kom txo qis thiab tsis muaj oxidants, xws li hauv HCl los yog acetic acid loops. Ntawm no, B-2 tsis yog tsuas yog kev tsim nyog xwb tab sis kuj yog qhov kev xaiv ua tau zoo tshaj plaws. Kev siv C-276 hauv qhov no yuav yog qhov tsis tsim nyog siv nyiaj.
Qhia meej C-276 thaum: Cov txheej txheem kwj yog hloov pauv, txhais tsis zoo, lossis muaj qee zaus oxidants. C-276's versatility muab kev nyab xeeb margin uas ua rau nws tus nqi siab dua. Yog tias muaj kev tsis ntseeg txog cov txheej txheem purity los yog muaj peev xwm rau huab cua ingress, C-276 yog qhov kev nyab xeeb dua, kev xaiv kev lag luam ntau dua hauv lub neej kom tsis txhob muaj kev puas tsuaj loj B-2.
Xaus: Hastelloy B-2 txias drawn yeeb nkab yog ib tug kws tshwj xeeb cov cuab yeej- qhov zoo tshaj plaws, siab -lub zog, precision tov rau qhov hnyav tshaj plaws, zoo- txhais, txo cov kev pab cuam acid. Nws txoj kev ncaj ncees nyiaj txiag nyob rau hauv nws qhov kev ua tau zoo tsis sib xws hauv nws cov niche tshwj xeeb, qhov twg lwm txoj hauv kev tsis ua tiav lossis sawv cev tus nqi tshaj qhov tshwj xeeb.
