1. Dab tsi yog qhov txhais cov yam ntxwv ntawm Hastelloy B phaj, thiab nws tsim tau li cas kom tau raws li cov kev cai nruj ntawm cov khoom siv tshuaj?
Hastelloy B phaj (UNS N10665) yog ib lub tiaj tus-cov khoom dov daim ntawv ntawm cov npib tsib xee-molybdenum alloy, feem ntau txhais tau tias muaj lub thickness ntawm 3/16 "(4.76mm) thiab ntau dua, nrog qhov dav tshaj 10" (250mm). Nws ua hauj lwm raws li lub hauv paus tsev thaiv rau fabricating chemical txheej txheem khoom xws li reactors, siab hlab ntsha, kab, thiab tso tsheb hlau luam.
Defining yam ntxwv:
Chemical Composition: Nominally 28% Molybdenum, 65% Nickel, nrog sib npaug hlau (2% max) thiab kab kawm. Cov ntsiab lus siab molybdenum muab qhov tshwj xeeb tiv thaiv kom tsis txhob muaj cov kua qaub, tshwj xeeb tshaj yog hydrochloric acid ntawm txhua qhov concentrations thiab kub txog rau qhov kub.
Microstructure: Siab austenitic (lub ntsej muag -centered cubic crystal qauv), uas tseem nyob ruaj khov los ntawm cryogenic kub mus txog rau annealing ntau. Cov qauv no muab zoo heev formability thiab toughness.
Corrosion Resistance Profile: Tsis zoo li cov hlau tsis zoo uas cia siab rau chromium rau kev ua kom dhau, B-2 qhov kev tiv thaiv los ntawm nws lub peev xwm los nyob hauv lub xeev "txo", tiv thaiv kev tawm tsam hauv qhov chaw tsis muaj oxidizing.
Kev tsim khoom:
Hastelloy B phaj yog tsim los ntawm ASTM B333 (Standard Specification rau Nickel-Molybdenum Alloy Phaj, Ntawv, thiab Sawb).
Melting thiab Refining: Cov hlau yog melted nyob rau hauv ib tug hluav taws xob arc rauv, ces refined nyob rau hauv ib tug Argon Oxygen Decarburization (AOD) hlab ntsha kom ua tiav chemistry thiab tshem tawm impurities. Rau cov ntawv thov tseem ceeb, nws yuav raug kho ntxiv los ntawm Electro-Slag Remelting (ESR) lossis Vacuum Arc Remelting (VAR) txhawm rau txhim kho kev huv thiab sib xws.
Ingot Casting: Cov hlau molten yog cam khwb cia rau hauv ingots hnyav ob peb tons.
Slabbing thiab Conditioning: Lub ingot yog kub dov rau hauv "slab" (cov duab plaub nruab nrab). Lub slab nto yog conditioned (hauv av) kom tshem tawm tej yam defects ntawm casting.
Kub Rolling (Plate Mill): Lub slab yog reheated thiab dhau los ntawm ib tug reversing phaj zeb, qhov twg nws yog txo mus rau qhov kawg thickness. Cov txheej txheem no yuav tsum muaj lub zog tseem ceeb vim B-2 lub zog siab ntawm qhov kub thiab txias.
Kev daws Annealing: Tom qab kub dov, lub phaj yog tov annealed los ntawm cua sov uniformly mus rau 2050℃F - 2150℃F (1120℃- 1175 degree) thiab ces sai sai dej quenched. Qhov no dissolves tej theem precipitated thiab tsim kom zoo corrosion-resistant microstructure.
Descaling thiab Pickling: Lub tshav kub-kho phaj yog abrasive blasted kom tshem tawm cov txheej txheem, ces pickled nyob rau hauv cov kua qaub da dej kom tshem tawm cov seem oxide txheej thiab rov ua kom cov corrosion-resistant nto.
Tiav thiab Kev Tshuaj Xyuas: Lub phaj yog leveled, trimmed mus rau qhov kawg qhov ntev, thiab undergoes nruj soj ntsuam nrog rau kev kuaj ultrasonic rau sab hauv soundness.
2. Thaum tsim cov tshuaj reactor nkoj los ntawm Hastelloy B phaj, qhov kev txiav txim siab vuam dab tsi yog qhov tseem ceeb los tiv thaiv "riam- kab tawm tsam" hauv tshav kub- cuam tshuam thaj chaw?
Fabricating siab hlab ntsha los ntawm Hastelloy B phaj yuav tsum tau ceev nrooj vuam tswj los tiv thaiv ib tug tshwj xeeb daim ntawv ntawm corrosion hu ua "riam-kab nres" - sai, localized corrosion tam sim ntawd nyob ib sab ntawm lub weld hlaws.
Kev Sib Tw Metallurgical:
Raws li tau tham hauv cov ntsiab lus dhau los, Hastelloy B-2 yog qhov cuam tshuam rau nag lossis daus ntawm intermetallic theem (theem - Ni₄Mo lossis Ni₃Mo) thaum raug kub ntawm 1200℃F txog 1600℃F (650℃txog 870 degree). Thaum lub sij hawm sib txuas ntawm cov phaj tuab, cov cua sov- cuam tshuam cheeb tsam (HAZ) rov ua dua los ntawm qhov ntsuas kub tseem ceeb. Yog tias qhov txias qeeb dhau lawm, molybdenum{10}} cov theem nplua nuj precipitate ntawm cov ciam teb nplej, depleting lawv ntawm corrosion kuj. Thaum raug hydrochloric acid, cov sensitized grain ciam teb yog nyiam tshaj tawm tsam, tsim ib tug sib sib zog nqus groove nyob rau hauv weld ntug - li no "riam-kab nres."
Kev txiav txim siab tseem ceeb ntawm vuam:
Low Heat Input: Siv qhov tsawg tshaj plaws amperage thiab siab tshaj plaws mus ncig ua si kom txo tau tag nrho cov cua kub nkag rau hauv lub phaj. Qhov no txo qhov dav ntawm HAZ thiab lub sijhawm siv nyob rau hauv qhov kev xav tau ntau yam.
Nruam Interpass Temperature Control: Rau multipass welds ntawm tuab phaj, qhov kub ntawm lub hauv paus hlau ntawm weld hla yuav tsum nruj me ntsis tswj, feem ntau qis dua 200℃F (93 degree). Qhov no tiv thaiv tshav kub buildup uas yuav cia ntev raug rau qhov rhiab heev ntau yam.
Back Purging: Thaum vuam cov hauv paus hla, cov roj inert (argon) purging ntawm sab hauv ntawm lub nkoj yog qhov tseem ceeb los tiv thaiv oxidation (qab zib) ntawm cov hauv paus hniav, uas tsim cov oxide inclusions uas tuaj yeem pib corrosion.
Filler Hlau Xaiv: Siv cov khoom sib xyaw ua ke hlau (ER Ni-Mo-7) uas ua tau raws li AWS A5.14 specifications. Lub muab tub lim yuav tsum tau hloov kho me ntsis chemistry los txhim kho cov hlau ductility.
Tom qab- Kev Kho Hniav Kub Kub (PWHT): Rau qhov siab tshaj plaws corrosion kuj, tag nrho cov khoom siv lub nkoj yuav tsum tau muab tshuaj annealed (2050℃F ua raws li ceev ceev quenching). Txawm li cas los xij, qhov no feem ntau siv tsis tau rau cov hlab ntsha loj. Raws li lwm txoj hauv kev, qee cov neeg tsim khoom siv cov qib thermally ruaj khov Hastelloy B-3, uas muaj cov nag lossis daus kinetics qeeb thiab muaj kev zam txim ntau dua thaum vuam.
Weld Procedure Qualification: Ua ntej vuam ntau lawm, Vuam txheej txheem Specification (WPS) yuav tsum tsim nyog. Qhov no suav nrog kev kuaj corrosion (ASTM G28 Method A) ntawm qhov vuam los ua pov thawj tias HAZ tsis tau hnov qab.
3. Cov txheej txheem corrosion ntawm Hastelloy B phaj txawv li cas hauv "txo" piv rau "oxidizing" acid ib puag ncig, thiab yuav ua li cas yog tias ib puag ncig hloov pauv tsis tau xav txog?
Kev nkag siab txog kev txhim kho corrosion ntawm Hastelloy B phaj yuav tsum paub qhov txawv ntawm kev txo qis thiab oxidizing ib puag ncig, vim tias cov hlau ua tau zoo sib txawv hauv txhua qhov.
Kev txo qis ib puag ncig (The Alloy's Strength):
Hauv kev txo cov kua qaub xws li hydrochloric acid (HCl) los yog sulfuric acid (H₂SO₄) ntawm qhov tsis tshua muaj siab / tsis muaj oxidizers, corrosion tshwm sim los ntawm cov txheej txheem uas hydrogen ions raug txo rau hydrogen gas, thiab hlau yaj li ions. Hastelloy B-2 ua tau zoo ntawm no vim:
Cov ntsiab lus siab molybdenum txhawb kev tsim kom ruaj khov, tiv thaiv zaj duab xis ntawm molybdenum oxides thiab ntsev uas yog insoluble hauv kev txo cov kua qaub.
Cov hlau tseem nyob hauv "active" tab sis maj mam corroding lub xeev, nrog corrosion feem ntau tsawg dua 0.1 hli / xyoo nyob rau hauv boiling HCl.
Oxidizing Ib puag ncig (The Alloy's Vulnerability):
Yog hais tias ib puag ncig muaj oxidizing hom (piv txwv li, yaj oxygen, ferric ions (Fe³⁺), cupric ions (Cu²⁺), nitric acid, los yog chromic acid), cov txheej txheem corrosion hloov pauv ntau:
Oxidizing agents tsa lub peev xwm electrochemical ntawm ib puag ncig.
Ntawm qhov muaj peev xwm siab dua no, molybdenum-nplua nuj zaj duab xis uas tiv thaiv hauv kev txo cov kua qaub tsis ruaj khov lawm.
Txawm li cas los xij, Hastelloy B-2 muaj cov chromium tsis txaus (1% max) los tsim cov chromium oxide passive zaj duab xis uas tiv thaiv stainless hlau hauv oxidizing acids.
Qhov tshwm sim: Cov hlau yog sab laug yam tsis muaj kev tiv thaiv zaj duab xis thiab dhau mus sai, zoo li corrosion los yog hnyav pitting.
Qhov phom sij ntawm kev npaj txhij txog ua haujlwm:
Qhov no ua rau muaj kev pheej hmoo ua haujlwm tseem ceeb. Xav txog cov txheej txheem kwj ntawm ntshiab hydrochloric acid (txo). Yog tias cov kab mob ferric chloride (FeCl₃) nkag mus rau hauv cov kwj deg vim yog cov khoom siv hluav taws xob txuas ntxiv ntawm cov pa roj carbon steel, ib puag ncig yuav oxidizing. Hastelloy B-2, uas ua tau zoo kawg nkaus, yuav dheev pib corroding ntawm tus nqi nrawm. Qhov no yog vim li cas cov txheej txheem chemistry tswj yog qhov tseem ceeb heev thaum siv B-2. Nws kuj yog vim li cas cov alloy Hastelloy C-276 (uas muaj chromium thiab tungsten) muaj nyob rau ib puag ncig uas tej zaum yuav voj voog ntawm txo thiab oxidizing tej yam kev mob.
4. Nyob rau hauv kev tsim cov loj - kab kab los yog cov hlab ntsha los ntawm Hastelloy B phaj, dab tsi yog qhov kev sib tw ntawm kev ua tiav cov kev daws teeb meem uas xav tau annealing thiab dej quenching?
Rau cov khoom siv loj loj xws li cov kab distillation lossis cov hlab ntsha reactor (muaj peev xwm 20-30 ko taw siab thiab 6-10 ko taw nyob rau hauv txoj kab uas hla), tom qab-fabrication tov annealing thiab quenching tam sim no tseem ceeb logistical thiab technical challenges.
Qhov Yuav Tsum Tau:
Raws li tsim, tshuaj annealing ntawm 2050℃F ua raws li sai quenching yog tib txoj kev los lav qhov kev tshem tawm cov teeb meem precipitated theem thiab rov ua kom tag nrho corrosion tsis kam tom qab vuam.
Cov kev sib tw ua tau zoo:
Kev txwv qhov cub loj: Feem ntau lub qhov cub kho cua sov muaj qhov txwv loj. Ib qho kev sib sau ua ke 40-ko taw yuav tsis haum rau hauv ib lub qhov cub muaj. Qhov no yuam cov neeg tsim khoom los xav txog lwm txoj hauv kev:
Sectional Fabrication: Lub nkoj yog fabricated nyob rau hauv seem uas haum rau hauv lub cub tawg, txhua seem yog tov annealed thiab quenched ib tug neeg, thiab ces cov seem yog teb -welded ua ke siv ib tug tsawg tshav kub input txheej txheem (feem ntau tawm hauv qhov kawg circumferential seam un-annealed tab sis tsim nyog los ntawm corrosion xeem).
PWHT Hauv Zos: Rau cov nozzles thiab cov ntawv txuas, cov hlua kho cua sov hauv zos yuav raug siv, txawm tias qhov no tsis zoo dua li kev sib tsoo tag nrho.
Quenching Distortion: Ceev ceev quenching los ntawm 2050℃F mus rau hauv da dej los yog tshuaj tsuag quench induces thermal shock. Loj, nyias- cov hlab ntsha phab ntsa yog qhov yooj yim rau:
Distortion/Warpage: Lub nkoj tuaj yeem tawm mus - ntawm - puag ncig lossis hneev nti, yuav tsum tau siv cov khoom siv kho kom zoo.
Residual Stresses: Tsis sib npaug quenching tuaj yeem kaw qhov kev ntxhov siab nyob hauv siab, uas yuav ua rau muaj kev ntxhov siab corrosion tawg tom qab.
Kev them nyiaj yug thaum kho: Ntawm 2050℃F, Hastelloy B muaj zog tsawg heev. Lub nkoj yuav tsum tau txais kev txhawb nqa nyob rau hauv lub cub tawg nyob rau hauv ib txoj kev uas tiv thaiv nws los ntawm sagging los yog collapsing nyob rau hauv nws tus kheej qhov hnyav. Qhov no yuav tsum muaj kev cai -tsim kev txhawb nqa eeb thiab ceev faj qhov kub thiab txias tsis sib xws.
Oxidation thiab Scaling: High-kub kho mob ua rau hnyav oxide nplai. Tom qab quenching, tag nrho cov hlab ntsha yuav tsum tau pickled (acid cleaned) los yog abrasive blasted kom tshem tawm cov nplai no thiab kho cov corrosion-resistant nto. Rau cov hlab ntsha loj, qhov no yuav tsum tau da dej kua qaub loj lossis kev ntxuav phau ntawv dav dav, uas yog lub sijhawm- siv thiab ua rau muaj kev nyuaj rau ib puag ncig thiab kev nyab xeeb.
Tus nqi: Kev sib xyaw ua ke ntawm kev teem caij tshwj xeeb rau lub tshuab hluav taws xob, kev tsim kho kev cai, quenching chaw, thiab tom qab- kev kho tu ua rau tag nrho cov hlab ntsha annealing kim heev, feem ntau ntxiv 30-50% rau tus nqi fabrication.
5. Dab tsi tshwj xeeb uas tsis yog - kev kuaj xyuas kev puas tsuaj (NDE) yog siv rau Hastelloy B phaj thaum lub sij hawm kev yuav khoom thiab kev tsim khoom, thiab lawv tsim cov teeb meem dab tsi los kuaj xyuas?
Muab qhov tseem ceeb ntawm cov cuab yeej tsim los ntawm Hastelloy B phaj, nruj tsis-kev kuaj xyuas kev puas tsuaj (NDE) yog siv rau ntawm ob qho tib si zeb (phaj tsim) thiab fabricator (tsim nkoj) theem. Cov kev cai yog feem ntau txhais los ntawm ASTM A435 / A577 rau phaj thiab ASME Boiler & Pressure Vessel Code, Tshooj V thiab VIII rau cov khoom siv fabricated.
Mill-Kev Tshawb Fawb Qib (Rau ASTM B333):
Kev Ntsuas Ultrasonic (UT) rau ASTM A578:
Lub hom phiaj: Thawj txoj hauv kev los tshuaj xyuas lub suab sab hauv ntawm lub phaj.
Kev kuaj pom tsis xws luag: Internal laminations, yeeb nkab (shrinkage voids from ingot solidification), non-metallic inclusions, and cracks. Lub phaj raug luam tawm hauv cov qauv kab sib chaws, thiab ib qho kev qhia ntau tshaj qhov kev siv (piv txwv li, lub tiaj- qhov hauv qab) ua rau tsis lees paub lossis kho.
Yuav Tsum Tau Theem: Rau cov kev pabcuam tseem ceeb, "Qib B" ntawm ASTM A578 (chav kawm nruj tshaj plaws) feem ntau tau teev tseg, yuav tsum tau 100% kev tshuaj ntsuam xyuas yam tsis muaj ib qho kev tsis zoo tshaj qhov loj me.
Liquid Penetrant Testing (PT) rau ASTM E165:
Lub Hom Phiaj: Tshawb xyuas cov npoo phaj thiab cov chaw siv tau rau saum npoo - rhuav tshem qhov tsis xws luag.
Kev kuaj pom tsis zoo: Laps, seams, tawg, los yog kua muag qhia thaum dov.
Dimensional soj ntsuam:
Thickness, flatness (camber), thiab squareness raug tshuaj xyuas tiv thaiv ASTM B333 kam rau ua.
Fabrication-Kev Tshawb Fawb Qib (Rau ASME Code):
Visual Examination (VT): 100% ntawm tag nrho cov kev npaj weld thiab tiav welds raug kuaj pom qhov tsis zoo.
Radiographic Testing (RT) rau ASME Tshooj V, Tshooj 2:
Lub hom phiaj: txhawm rau tshuaj xyuas qhov zoo ntawm cov khoom siv welds.
Kev kuaj pom tsis zoo: Tsis muaj fusion, tsis muaj kev nkag mus, porosity, slag inclusions (yog tias siv cov hlau muab tub lim), thiab cov kab nrib pleb hauv cov hlau txuas thiab HAZ uas nyob ib sab. Tag nrho cov duab hluav taws xob feem ntau yog xav tau rau Qeb A thiab B pob qij txha hauv cov hlab ntsha siab.
Liquid Penetrant Testing (PT) ntawm Welds:
Purpose: To detect surface cracks or porosity in the weld cap and, where accessible, the weld root.
Vim li cas PT dhau MT: Txij li Hastelloy B tsis yog -magnetic, Magnetic Particle Test (MT) siv tsis tau. PT yog tus qauv kev soj ntsuam saum npoo.
Kev Ntsuas Hydrostatic:
Tom qab kev tsim khoom, lub nkoj ua tiav yog ntim nrog dej thiab nias rau 1.3 npaug ntawm qhov kev tsim siab (lossis ib qho kev cai lij choj) txhawm rau txheeb xyuas tag nrho kev ncaj ncees thiab xau- nruj.
Positive Material Identification (PMI):
Ua ntej lub phaj raug tso tawm rau kev tsim thiab tom qab vuam, PMI siv X-ray fluorescence (XRF) analyzers feem ntau ua los xyuas kom meej tias lub hauv paus phaj thiab vuam muab tub lim hlau phim cov qib uas tau teev tseg, tiv thaiv cov nqi sib tov-ups.
