1. Kev Ntsuas thiab Kev Tshawb Fawb Txog Kev Xav
Ntawm 3cov qhov rooj log tshebcov qauv uas lub tuam txhab muab, 2 yog cov li qub, thiab 1 yog lub li qub uas tseem tsis tau siv. Rau A thiab B, lub li qub uas tseem tsis tau siv yog cim ua xim grey. Daim Duab Qhia Txog 1. Sab nraud ntawm lub li qub A yog qhov ntiav, sab nraud ntawm lub li qub B yog qhov chaw, sab nraud ntawm lub li qub C yog qhov chaw, thiab sab nraud ntawm lub li qub C yog qhov chaw. Cov li qub A thiab B yog npog nrog cov khoom xeb. Lub li qub A thiab B tawg ntawm qhov khoov, sab nraud ntawm qhov khoov yog raws lub li qub, lub qhov ncauj ntawm lub li qub B tawg mus rau qhov kawg, thiab tus xub dawb ntawm qhov tawg ntawm qhov chaw ntawm lub li qub A yog cim. Los ntawm saum toj no, cov kab nrib pleb nyob txhua qhov chaw, cov kab nrib pleb yog qhov loj tshaj plaws, thiab cov kab nrib pleb nyob txhua qhov chaw.
Ib ntu ntawmlub qhov rooj log tshebCov qauv A, B, thiab C raug txiav los ntawm qhov khoov, thiab cov qauv ntawm qhov chaw tau pom nrog lub tshuab tsom iav ZEISS-SUPRA55, thiab cov khoom sib xyaw ua ke tau soj ntsuam nrog EDS. Daim duab 2 (a) qhia txog cov qauv me me ntawm qhov chaw valve B. Nws tuaj yeem pom tias muaj ntau cov khoom dawb thiab ci ntsa iab ntawm qhov chaw (qhia los ntawm cov xub dawb hauv daim duab), thiab kev tshuaj xyuas EDS ntawm cov khoom dawb muaj cov ntsiab lus siab ntawm S. Cov txiaj ntsig ntawm kev tshuaj xyuas lub zog ntawm cov khoom dawb tau pom hauv Daim duab 2 (b).
Cov Duab 2 (c) thiab (e) yog cov qauv ntawm qhov chaw ntawm lub valve B. Nws tuaj yeem pom los ntawm Daim Duab 2 (c) tias qhov chaw yuav luag tag nrho yog cov khoom xeb, thiab cov khoom xeb ntawm cov khoom xeb los ntawm kev tshuaj xyuas lub zog spectrum feem ntau suav nrog S, Cl thiab O, cov ntsiab lus ntawm S nyob rau hauv txhua qhov chaw yog siab dua, thiab cov txiaj ntsig ntawm kev tshuaj xyuas lub zog spectrum tau qhia hauv Daim Duab 2 (d). Nws tuaj yeem pom los ntawm Daim Duab 2 (e) tias muaj cov kab nrib pleb me me raws lub nplhaib valve ntawm qhov chaw ntawm lub valve A. Cov Duab 2 (f) thiab (g) yog cov qauv ntawm qhov chaw ntawm lub valve C, qhov chaw kuj tau npog tag nrho los ntawm cov khoom xeb, thiab cov khoom xeb kuj suav nrog S, Cl thiab O, zoo ib yam li Daim Duab 2 (e). Qhov laj thawj rau kev tawg tej zaum yuav yog kev ntxhov siab xeb tawg (SCC) los ntawm kev tshuaj xyuas cov khoom xeb ntawm qhov chaw ntawm lub valve. Daim Duab 2 (h) kuj yog qhov microstructure ntawm lub valve C. Nws tuaj yeem pom tias qhov chaw huv si, thiab cov tshuaj lom neeg ntawm qhov chaw uas EDS tau soj ntsuam zoo ib yam li cov tooj liab, qhia tias lub valve tsis xeb. Los ntawm kev sib piv cov qauv me me thiab cov tshuaj lom neeg ntawm peb qhov chaw valve, nws tau qhia tias muaj cov xov xwm corrosive xws li S, O thiab Cl hauv ib puag ncig.
Qhov tawg ntawm lub valve B tau qhib los ntawm kev sim khoov, thiab pom tias qhov tawg tsis nkag mus rau hauv tag nrho qhov seem ntawm lub valve, tawg rau ntawm sab ntawm qhov nraub qaum, thiab tsis tawg rau ntawm sab rov qab ntawm lub valve. Kev tshuaj xyuas qhov tawg qhia tau hais tias xim ntawm qhov tawg yog tsaus, qhia tias qhov tawg tau raug xeb, thiab qee qhov ntawm qhov tawg yog xim tsaus, uas qhia tau hais tias qhov xeb hnyav dua hauv cov khoom no. Qhov tawg ntawm lub valve B tau pom nyob rau hauv lub tshuab scanning electron, raws li pom hauv Daim Duab 3. Daim Duab 3 (a) qhia txog qhov pom ntawm qhov tawg ntawm lub valve B. Nws tuaj yeem pom tias qhov tawg sab nraud ze ntawm lub valve tau npog los ntawm cov khoom xeb, dua qhia txog qhov muaj cov xov xwm xeb hauv ib puag ncig. Raws li kev tshuaj xyuas spectrum zog, cov khoom siv tshuaj lom neeg ntawm cov khoom xeb feem ntau yog S, Cl thiab O, thiab cov ntsiab lus ntawm S thiab O yog qhov siab, raws li pom hauv Daim Duab 3 (b). Kev soj ntsuam qhov tawg, nws pom tias tus qauv loj hlob ntawm qhov tawg yog raws li hom siv lead ua. Kuj tseem pom tau ntau qhov tawg thib ob los ntawm kev saib qhov tawg ntawm qhov loj dua, raws li pom hauv Daim Duab 3 (c). Cov tawg thib ob tau cim nrog cov xub dawb hauv daim duab. Cov khoom xeb thiab cov qauv loj hlob ntawm qhov tawg dua qhia txog cov yam ntxwv ntawm kev ntxhov siab xeb tawg.
Qhov tawg ntawm lub valve A tsis tau qhib, tshem tawm ib feem ntawm lub valve (suav nrog qhov chaw tawg), sib tsoo thiab txhuam qhov seem axial ntawm lub valve, thiab siv Fe Cl3 (5 g) + HCl (50 mL) + C2H5OH (100 mL) kua tau etched, thiab cov qauv metallographic thiab cov qauv loj hlob ntawm qhov tawg tau pom nrog Zeiss Axio Observer A1m optical microscope. Daim duab 4 (a) qhia cov qauv metallographic ntawm lub valve, uas yog α + β dual-phase qauv, thiab β yog qhov zoo thiab granular thiab faib rau ntawm α-phase matrix. Cov qauv tawg ntawm cov kab nrib pleb circumferential tau pom hauv Daim duab 4 (a), (b). Txij li thaum cov nplaim tawg puv nrog cov khoom xeb, qhov sib txawv ntawm ob qhov nplaim tawg yog dav, thiab nws nyuaj rau qhov sib txawv ntawm cov qauv tawg. bifurcation phenomenon. Ntau qhov tawg thib ob (cim nrog cov xub dawb hauv daim duab) kuj tau pom ntawm qhov tawg thawj zaug no, saib Daim duab 4 (c), thiab cov kab nrib pleb thib ob no tau nthuav dav raws cov noob. Cov qauv valve etched tau pom los ntawm SEM, thiab nws tau pom tias muaj ntau qhov tawg me me hauv lwm qhov chaw sib luag rau qhov tawg tseem ceeb. Cov kab nrib me me no tau pib los ntawm qhov chaw thiab nthuav dav mus rau sab hauv ntawm lub valve. Cov kab nrib muaj bifurcation thiab nthuav dav raws cov noob, saib Daim Duab 4 (c), (d). Ib puag ncig thiab lub xeev kev ntxhov siab ntawm cov microcracks no yuav luag zoo ib yam li cov ntawm qhov tawg tseem ceeb, yog li nws tuaj yeem xaus lus tias daim ntawv nthuav dav ntawm qhov tawg tseem ceeb kuj yog intergranular, uas kuj tau lees paub los ntawm kev soj ntsuam qhov tawg ntawm lub valve B. Qhov tshwm sim bifurcation ntawm qhov tawg dua qhia txog cov yam ntxwv ntawm kev ntxhov siab corrosion tawg ntawm lub valve.
2. Kev Tshawb Fawb thiab Kev Sib Tham
Hauv kev xaus lus, nws tuaj yeem xaus lus tias qhov kev puas tsuaj ntawm lub valve yog tshwm sim los ntawm kev ntxhov siab corrosion tawg los ntawm SO2. Kev ntxhov siab corrosion tawg feem ntau yuav tsum ua kom tau raws li peb qhov xwm txheej: (1) cov ntaub ntawv rhiab rau kev ntxhov siab corrosion; (2) corrosive medium rhiab rau tooj liab alloys; (3) qee yam kev ntxhov siab.
Feem ntau ntseeg tias cov hlau ntshiab tsis raug kev txom nyem los ntawm kev ntxhov siab corrosion, thiab txhua yam alloys muaj kev cuam tshuam rau kev ntxhov siab corrosion rau ntau qib. Rau cov khoom siv tooj dag, feem ntau ntseeg tias cov qauv dual-phase muaj kev ntxhov siab corrosion ntau dua li cov qauv ib-theem. Nws tau tshaj tawm hauv cov ntaub ntawv tias thaum cov ntsiab lus Zn hauv cov khoom siv tooj dag tshaj 20%, nws muaj kev ntxhov siab corrosion ntau dua, thiab cov ntsiab lus Zn siab dua, qhov siab dua qhov kev ntxhov siab corrosion. Cov qauv metallographic ntawm lub nozzle roj hauv qhov no yog α + β dual-phase alloy, thiab cov ntsiab lus Zn yog li 35%, ntau tshaj 20%, yog li nws muaj kev ntxhov siab corrosion siab thiab ua tau raws li cov khoom siv xav tau rau kev ntxhov siab corrosion tawg.
Rau cov khoom siv tooj dag, yog tias kev txo kev ntxhov siab tsis ua tiav tom qab ua haujlwm txias deformation, kev ntxhov siab corrosion yuav tshwm sim nyob rau hauv cov xwm txheej kev ntxhov siab thiab qhov chaw corrosive. Kev ntxhov siab uas ua rau kev ntxhov siab corrosion tawg feem ntau yog kev ntxhov siab tensile hauv zos, uas tuaj yeem siv kev ntxhov siab lossis kev ntxhov siab seem. Tom qab lub log tsheb thauj khoom inflated, kev ntxhov siab tensile yuav tsim raws li qhov kev taw qhia axial ntawm lub nozzle cua vim yog lub siab siab hauv lub log, uas yuav ua rau muaj kev tawg circumferential hauv lub nozzle cua. Kev ntxhov siab tensile los ntawm lub siab sab hauv ntawm lub log tuaj yeem suav tau yooj yim raws li σ = p R / 2t (qhov twg p yog lub siab sab hauv ntawm lub log, R yog lub cheeb tsam sab hauv ntawm lub valve, thiab t yog phab ntsa thickness ntawm lub valve). Txawm li cas los xij, feem ntau, kev ntxhov siab tensile tsim los ntawm lub siab sab hauv ntawm lub log tsis loj dhau, thiab cov nyhuv ntawm kev ntxhov siab seem yuav tsum tau xav txog. Qhov chaw tawg ntawm cov roj nozzles yog txhua yam ntawm backbend, thiab nws yog qhov tseeb tias qhov seem deformation ntawm backbend yog loj, thiab muaj kev ntxhov siab tensile seem nyob ntawd. Qhov tseeb, hauv ntau yam khoom siv tooj liab, kev ntxhov siab corrosion tawg tsis tshua muaj los ntawm kev tsim qauv kev ntxhov siab, thiab feem ntau ntawm lawv yog tshwm sim los ntawm kev ntxhov siab seem uas tsis pom thiab tsis quav ntsej. Hauv qhov no, ntawm qhov khoov rov qab ntawm lub valve, qhov kev taw qhia ntawm kev ntxhov siab tensile tsim los ntawm lub siab sab hauv ntawm lub log tsheb yog sib xws nrog qhov kev taw qhia ntawm kev ntxhov siab seem, thiab qhov sib tshooj ntawm ob qhov kev ntxhov siab no muab qhov xwm txheej ntxhov siab rau SCC.
3. Xaus Lus thiab Cov Lus Qhia
Xaus lus:
Qhov tawg ntawmlub qhov rooj log tshebfeem ntau yog tshwm sim los ntawm kev ntxhov siab corrosion cracking los ntawm SO2.
Cov Lus Qhia
(1) Nrhiav qhov chaw ntawm cov khoom siv corrosive hauv ib puag nciglub qhov rooj log tsheb, thiab sim tsis txhob kov ncaj qha rau cov khoom siv corrosive nyob ib puag ncig. Piv txwv li, ib txheej ntawm cov txheej tiv thaiv corrosion tuaj yeem siv rau ntawm qhov chaw ntawm lub valve.
(2) Qhov kev ntxhov siab tensile seem ntawm kev ua haujlwm txias tuaj yeem raug tshem tawm los ntawm cov txheej txheem tsim nyog, xws li kev txo kev ntxhov siab annealing tom qab khoov.
Lub sijhawm tshaj tawm: Cuaj hlis-23-2022
