Q1: Dab tsi yog qhov txhais cov yam ntxwv ntawm kev tsim qauv ASTM B574, thiab vim li cas nws thiaj li tshwj xeeb rau UNS N10276?
Teb:
ASTM B574 yog tus qauv qhia tshwj xeeb rau npib tsib xee- alloy bars ua los ntawm cov khoom tshwj xeeb corrosion-cov hlau tiv taus, suav nrog UNS N10276 (Hastelloy C-276). Kev nkag siab txog tus qauv no yog qhov tseem ceeb rau kev yuav khoom thiab kev tswj xyuas zoo hauv kev lag luam xws li kev ua tshuaj lom neeg thiab roj & roj.
Lub ntsiab lus ntawm ASTM B574 yog tias nws tswj hwm "tus qauv yuav tsum tau ua" rau kub-tiav thiab txias- cov khoom tiav hauv cov xwm txheej tshwj xeeb. Nws dictates qhov tso cai kam rau ua rau qhov ntev (inch, thickness, ntev), ncaj, thiab tiav. Thaum koj xaj rau qhov kev qhia tshwj xeeb no, koj tau lees paub qee theem ntawm kev ntseeg siab thiab qhov ntsuas qhov tseeb.
Tshwj xeeb rau UNS N10276, ASTM B574 xyuas kom lub bar yog tsim los ntawm cov txheej txheem xws li kub dov, forging, los yog txias kos duab, ua raws li annealing thiab descaling. Tus txheej txheem mandates hais tias cov hlau yuav muab rau hauv cov tshuaj annealed mob (feem ntau ntawm 1121℃/ 2050℃F, ua raws li sai quenching). Qhov kev kho cua sov no yog qhov tseem ceeb rau C-276 vim nws ua kom ntseeg tau tias cov txheej txheem topologically close-packed (TCP), zoo li mu theem, yog yaj, rov ua kom cov alloy qhov tshwj xeeb corrosion kuj. Yog tias tsis muaj qhov tshwj xeeb annealing tau txib los ntawm ASTM B574, cov khoom yuav raug cuam tshuam rau intergranular corrosion hauv kev tawm tsam hnyav.
Q2: Nyob rau hauv cov nqe lus ntawm cov tshuaj muaj pes tsawg leeg thiab corrosion kuj, dab tsi ua rau UNS N10276 (Hastelloy C-276) sawv tawm ntawm tus qauv stainless hlau zoo li 316L?
Teb:
Qhov sib txawv tseem ceeb yog nyob rau hauv cov tshuaj muaj pes tsawg leeg thiab nws cov txiaj ntsig ua rau cov tshuaj tiv thaiv hauv zos thiab txo cov acids.
Thaum 316L stainless hlau cia siab rau chromium rau passivity nyob rau hauv oxidizing ib puag ncig, UNS N10276 yog nickel -chromium- molybdenum alloy nrog cov ntsiab lus tseem ceeb tungsten thiab hlau. Qhov sib txawv tseem ceeb yog cov ntsiab lus molybdenum siab heev (15.0 - 17.0%) thiab ntxiv ntawm tungsten (3.0 - 4.5%).
Kev Ua Phem Rau Txo Cov Acids: 316L tawm tsam hauv kev txo qis ib puag ncig zoo li hydrochloric acid lossis sulfuric acid ntawm qhov kub nruab nrab. Lub siab molybdenum thiab tungsten cov ntsiab lus hauv C-276 muab kev ua haujlwm zoo kawg nkaus rau cov kua qaub no, tiv thaiv kev tawm tsam sai, tsis sib xws.
Chloride Stress Corrosion Cracking (SCC): 316L yog qhov tsis zoo rau cov tshuaj chloride SCC hauv qhov chaw kub chloride. UNS N10276, nrog nws cov ntsiab lus siab nickel (sib npaug, feem ntau 57% tshuav), muaj qhov tshwj xeeb tiv thaiv SCC.
Localized Corrosion: Cov ntsiab lus siab molybdenum kuj muab kev tiv thaiv zoo rau pitting thiab crevice corrosion piv rau 316L.
Oxidizing Media: Thaum 316L tso siab rau chromium, C-276 kuj muaj txog 14.5-16.5% chromium, uas tso cai rau nws tiv taus oxidizing cov neeg ua haujlwm. Txawm li cas los xij, nws lub zog muaj tseeb yog nws qhov kev ua tau zoo thoob plaws ob qho tib si oxidizing thiab txo cov xwm txheej, thaum 316L feem ntau txwv rau oxidizing ib puag ncig.
Q3: Tus kws tshaj lij qhia ASTM B574 UNS N10276 tuav rau lub reactor nyob rau hauv ib chav tsev flue gas desulfurization (FGD). Dab tsi tshwj xeeb cov khoom ntawm cov hlau no ua pov thawj nws cov kev xaiv ntau dua - tus nqi duplex stainless hlau?
Teb:
Nyob rau hauv ib puag ncig hnyav ntawm Flue Gas Desulfurization (FGD) system, kev xaiv UNS N10276 yog tsav los ntawm nws qhov kev tiv thaiv tsis sib xws rau qhov "tsawg-pH chloride" ib puag ncig.
FGD scrubbers lis slurries ntawm limestone thiab gypsum, tab sis qhov tseem ceeb corrosive agents yog cov condensed acids. Chlorides tam sim no nyob rau hauv cov thee los yog flue gas tsim hydrochloric acid (HCl), thaum sulfur oxides tsim sulfurous thiab sulfuric acid (H₂SO₃/H₂SO₄). Qhov no tsim ib qho tshwj xeeb "qaub" ib puag ncig nrog pH qis thiab cov chlorides siab ib txhij.
Crevice Corrosion Resistance: Duplex stainless hlau muaj qhov txwv ntawm Critical Crevice Corrosion Temperature (CCCT) hauv siab -chloride ib puag ncig. Nyob rau hauv FGD deposits (scale) qhov twg cov mob stagnant tshwm sim, duplex qib yuav sai sai pit los yog crevice corrode. UNS N10276, nrog nws tus lej PRE siab (Pitting Resistance Equivalent), tuaj yeem tiv taus cov xwm txheej no txawm tias qhov kub siab.
Uniform Attack: Cov ntsiab lus sulfuric acid tuaj yeem tua cov txheej txheem ntawm duplex steels. Cov npib tsib xee- molybdenum matrix ntawm C-276 yog inherently resistant rau qhov txo qhov ntawm cov kua qaub sib tov.
Erosion-Corrosion: FGD slurries yog abrasive. Thaum hardness plays lub luag hauj lwm, lub peev xwm ntawm C-276 los tuav nws cov zaj duab xis passive nyob rau hauv mechanical abrasion (erosion-corrosion) yog superior rau cov qib duplex. Txawm hais tias tus nqi ntawm cov khoom siv pib ntawm C-276 yog qhov siab dua, nyob rau hauv cov cheeb tsam tseem ceeb xws li lub qhov nqus nkag los yog qhov hluav taws xob ducts, tus nqi ntawm lub neej yog qis dua vim tias nws tiv thaiv kev puas tsuaj loj thiab tsis tau npaj tseg rau kev kho weld uas yuav tsim nyog nrog cov ntaub ntawv duplex.
Q4: Dab tsi yog qhov tseem ceeb rau kev ua haujlwm ASTM B574 UNS N10276 tuav rau hauv cov khoom tiav?
Teb:
UNS N10276 tau muab cais ua ib qho nyuaj-rau- tshuab alloy vim nws qhov ua haujlwm siab hardening tus nqi thiab siab shear zog. Machining ASTM B574 tuav yuav tsum muaj cov tswv yim tshwj xeeb kom ua tiav qhov tseeb thiab qhov chaw tiav yam tsis muaj kev puas tsuaj rau cov khoom.
Ua hauj lwm Hardening: Zoo li ntau nickel alloys, C-276 ua hauj lwm hardens sai heev. Yog hais tias lub cuab tam rubs es tsis txhob txiav, nws tsim ib tug hardened txheej uas ua rau tom ntej hla kev nyuaj thiab ceev cov cuab yeej hnav. Yog li ntawd, nws yog ib qho tseem ceeb kom tswj tau qhov kev txiav txim zoo thiab tsis txhob cia lub cuab yeej nyob.
Tooling: Carbide cov cuab yeej yog tus qauv. Lawv yuav tsum tau ceev nrooj thiab hloov ntawm lub sijhawm tsis tu ncua. Siv cov cuab yeej zoo rake lub kaum sab xis pab txiav cov hlau tsis yog thawb nws. Coated carbides (xws li AlTiN lossis TiAlN) feem ntau yog siv los txo cov cua sov ntawm qhov txiav.
Kev Tswj Xyuas Thaum Tshav Kub Kub: Cov alloy tuav lub zog siab ntawm qhov kub siab, txhais tau tias txiav quab yuam siab, thiab cua sov yog tsim. Tsis zoo li cov hlau, cov chips tsis nqa tawm feem ntau ntawm cov cua sov. Yog li ntawd, siab -siab, siab- ntim cov coolant yog qhov tseem ceeb los tswj cov cua sov ntawm lub cuab yeej-workpiece interface, tiv thaiv kev ua haujlwm hardening, thiab tshem tawm cov chips.
Surface Integrity: Cov ntsiab lus tsis tshua muaj leej faj (max 0.03%) hauv tus qauv ASTM B574 C-276 txhais tau tias nws tuaj yeem tsim cov tawv tawv, tawv tawv. Chip breakers yog qhov tseem ceeb rau kev tswj. Tsis tas li ntawd, kev tuav lub ntsej muag zoo tsis yog kom zoo nkauj xwb; ib tug ntxhib nto tuaj yeem ua raws li kev ntxhov siab riser lossis qhov chaw rau kev pib corrosion hauv kev pabcuam.
Q5: Cov kev kho cua sov li cas uas tau teev tseg los ntawm ASTM B574 cuam tshuam rau kev sib txuas thiab tom qab-weld corrosion kuj ntawm UNS N10276 tuav?
Teb:
ASTM B574 xav kom cov tuav yuav tsum tau muab nyob rau hauv cov mob annealed. Qhov kev pib no yog lub hauv paus rau qhov zoo weldability thiab feem ntau hu ua "mill annealed" lossis "solution treated" state.
Thaum vuam UNS N10276, qhov kev pheej hmoo tseem ceeb tsis yog kub tawg (xws li qee cov aluminium alloys) tab sis nag lossis daus ntawm cov theem sib txawv hauv thaj chaw kub ntxhov (HAZ) thiab kev sib cais ntawm cov hlau alloying.
Pib Microstructure: Cov mob annealed ua kom muaj homogeneous, ib zaug -theem austenitic microstructure nrog carbides thiab intermetallic tag nrho yaj. Yog hais tias lub bar nyob rau hauv un-annealed los yog tsis tsim nyog annealed lub xeev, nws tej zaum yuav muaj cov theem detrimental uas yuav ua raws li cov ntsiab lus pib rau tawg thaum vuam.
Post- Weld Corrosion: Qhov tseem ceeb tshaj plaws yog "weld decay" lossis HAZ nres hauv kev pabcuam corrosive. Thaum lub sij hawm vuam, HAZ muaj qhov kub thiab txias uas tuaj yeem ua rau nag lossis daus ntawm carbides thiab mu theem (ib qho sib xyaw intermetallic) ntawm cov ciam teb. Qhov no depletes thaj chaw nyob ib sab ntawm molybdenum thiab chromium, ua rau nws raug rau intergranular corrosion.
Kev daws: Vim tias ASTM B574 C-276 muaj cov pa roj carbon tsawg thiab silicon, nws txo qis carbide nag lossis daus. Txawm li cas los xij, txhawm rau kom ntseeg tau qhov siab tshaj plaws ntawm corrosion kuj nyob rau hauv raws li -welded mob, txuam muab tub lim hlau (xws li ERNiCrMo-4 los yog ERNiCrMo{10}}10) feem ntau yog siv. Thaum C-276 feem ntau yog siv rau hauv qhov chaw zoo li-welded rau ntau qhov chaw, rau qhov kev tawm tsam hnyav tshaj plaws (xws li cov roj HCl ntub dej), cov tshuaj tom qab vuam annealing yuav tsum tau rov ua kom rov ua kom tiav cov theem nrab uas tau tsim thaum lub sij hawm vuam, kho cov microstructure rau cov xwm txheej thaum ub los ntawm ASTM B574.
