Ferritic stainless hlau hais txog stainless hlau nrog lub cev-centered cubic ferrite raws li cov qauv matrix ntawm qhov kub thiab txias. Ferritic stainless hlau muaj hlau thiab chromium ua cov ntsiab lus tseem ceeb, feem ntau tsis muaj npib tsib xee, thiab qee qhov muaj me me ntawm molybdenum, titanium lossis niobium thiab lwm yam khoom. Nws muaj qhov zoo oxidation tsis kam, corrosion kuj thiab chloride corrosion cracking kuj. Tsis tas li ntawd, ferritic stainless hlau kuj muaj cov yam ntxwv ntawm cov thermal conductivity loj, me me expansion coefficient, zoo oxidation kuj, thiab zoo heev kev nyuaj siab corrosion kuj. Nws feem ntau yog siv los tsim cov khoom uas tiv taus huab cua, dej vapor, dej, thiab oxidative acid corrosion. Cov neeg sawv cev qib ntawm ferritic stainless hlau yog: AISI 410 (UNS S41000), AISI 420 (UNS S42000), AISI 430 (UNS S43000) raws li ASTM; 1.4006, 1.4021, 1.4016, raws li EN tus qauv ... thiab lwm yam.
Ferritic stainless hlau tuaj yeem muab faib ua cov chromium tsawg, nruab nrab chromium thiab siab chromium raws li cov ntsiab lus chromium. Raws li cov purity ntawm cov hlau, tshwj xeeb tshaj yog cov ntsiab lus ntawm carbon thiab nitrogen impurities, nws yuav muab faib mus rau hauv zoo tib yam ferritic stainless hlau thiab ultra-ntshiab ferritic stainless hlau. Ordinary ferritic stainless hlau muaj qhov tsis zoo ntawm qhov kub thiab txias ntawm chav tsev kub brittleness, notch rhiab heev, siab intergranular corrosion nyiam, thiab tsis zoo weldability. Txawm hais tias hom hlau no tau tsim ua ntej, nws daim ntawv thov kev lag luam tau txwv ntau heev. Cov kev tsis zoo ntawm cov hlau tsis zoo li qub ferritic stainless hlau muaj feem xyuam rau cov purity ntawm cov hlau, tshwj xeeb tshaj yog cov ntsiab lus siab ntawm interstitial ntsiab xws li carbon thiab nitrogen hauv cov hlau. Ntev npaum li cov pa roj carbon thiab nitrogen hauv cov hlau tsis txaus, cov kev tsis txaus siab saum toj no tuaj yeem kov yeej.
Piv nrogaustenitic stainless hlau, ferritic stainless hlau muaj zoo corrosion kuj, tshav kub tsis kam thiab processability. Txij li thaum ferrite theem tsis tuaj yeem yaj cov pa roj carbon, ferrite muaj cov yam ntxwv ntawm kev muag muag thiab yooj yim rau deform. Zoo li martensitic stainless hlau, vim lub lattice qauv yog lub cev-centered cubic qauv, nws yog paramagnetic, yog li ferritic stainless hlau yog sib nqus. Austenitic stainless hlau tsis yog hlau nplaum vim nws lub ntsej muag-centered cubic qauv.
Tus nqi ntawm ferritic stainless hlau tsis yog tsuas yog qis thiab ruaj khov, tab sis kuj muaj ntau yam tshwj xeeb thiab qhov zoo. Nws tau raug pov thawj tias ferritic stainless hlau yog ib qho khoom siv zoo heev.
Ordinary ferritic stainless hlau
Cov hlau no suav nrog cov ntsiab lus qis, nruab nrab thiab siab chromium. Tsawg-chromium ferritic stainless hlau muaj li ntawm 11% mus rau 14% chromium, xws li 00Cr12 thiab 0Cr13Al hauv Suav teb. American AISI 400, 405, 406MF-2. Cov hlau no muaj zoo toughness, plasticity, txias deformation thiab weldability. Vim tias cov hlau muaj qee yam ntawm chromium thiab txhuas, nws muaj oxidation zoo thiab xeb kuj. 405 tuaj yeem siv ua roj av refining ntauwd, tank hauv ob sab phlu, chav turbine hniav, siab kub sulfur corrosion resistant ntaus ntawv, thiab lwm yam thiab lwm yam. Nruab nrab chromium ferritic stainless hlau, cov ntsiab lus chromium yog 14% mus rau 19%, xws li 1Cr17 thiab 1Cr17Mo hauv Suav teb. AISI 429, AISI 430, AISI 433, AISI 434, AISI 435, AISI 436, AISI 439 hauv Tebchaws Meskas. Hom hlau no zoo dua xeb thiab corrosion kuj. Nws txoj hauj lwm hardening coefficient yog me me (n≈2), thiab nws muaj qhov zoo sib sib zog nqus nqus kev ua tau zoo, tab sis nws cov ductility tsis zoo. AISI 430 ferritic stainless hlau yog siv rau kev kho kom zoo nkauj architectural, kho kom zoo nkauj tsheb, khoom siv hauv chav ua noj, roj burners thiab cov khoom siv nitric acid, thiab lwm yam. AISI 434 yog siv rau kev kho kom zoo nkauj sab nrauv ntawm lub tsheb thiab cov tsev. 439 yog siv los ua ib lub hose rau cov dej rhaub roj, cov kav dej thiab cov kav dej, thiab lwm yam. High chromium ferritic stainless hlau muaj 19% mus rau 30% chromium, xws li Cr18Si2 thiab Cr25 hauv Suav teb, AISI 442, AISI 443 thiab AISI 446 hauv Tebchaws Meskas. Xeev. Cov hlau zoo li no muaj kev tiv thaiv oxidation zoo. AISI 442 yog siv tsis tu ncua nyob rau hauv cov huab cua, lub siab txwv kub yog 1035 ° C, thiab qhov siab tshaj plaws kub rau kev siv tas mus li yog 980 ° C. AISI 446 ferritic stainless hlau muaj oxidation zoo dua.
High-purity ferritic stainless hlaul
Hom hlau no muaj cov pa roj carbon tsawg heev, nitrogen; siab chromium, molybdenum, titanium, niobium thiab lwm yam khoom. Xws li Tuam Tshoj tus 00Cr17Mo, 00Cr18Mo2, 00Cr26Mol, 00Cr30Mo2. Cov hlau no muaj cov khoom siv zoo (tshwj xeeb yog toughness), weldability, intergranular corrosion kuj, pitting corrosion kuj, crevice corrosion kuj, thiab zoo heev kev nyuaj siab corrosion cracking kuj. Piv txwv li, 18-2 ferritic stainless hlau muaj corrosion kuj zoo nyob rau hauv nitric acid, acetic acid, NaOH, pitting corrosion kuj nyob rau hauv 3% NaCl thiab FeCl3 yog sib npaug los yog tshaj 18-8 austenitic stainless hlau, 26CrMo hlau nyob rau hauv ntau yam xov xwm Corrosion kuj. , tshwj xeeb tshaj yog nyob rau hauv cov organic acids, oxidizing acids, thiab muaj zog alkalis. Nws muaj zoo pitting corrosion kuj nyob rau hauv muaj zog chloride nruab nrab. Tsis muaj kev ntxhov siab corrosion tawg tshwm sim hauv chloride, hydrogen sulfide, ntau sulfuric acid thiab muaj zog alkali. 30Cr-2Mo muaj kev tiv thaiv ntau dua rau pitting corrosion thiab crevice corrosion thaum tswj kev ntxhov siab corrosion.
Corrosion kuj ntawm ferritic stainless hlau
(1) Uniform corrosion.
Chromium yog qhov yooj yim tshaj plaws rau passivate. Nyob rau hauv ib puag ncig atmospheric, hlau-chromium alloy nrog cov ntsiab lus chromium ntau dua 12% tuaj yeem ua tus kheej-passivated. Hauv qhov nruab nrab oxidizing, cov ntsiab lus chromium tuaj yeem passivated yog tias nws yog ntau tshaj 17%. Nyob rau hauv ib co corrosive nruab nrab, siab chromium thiab molybdenum, npib tsib xee, tooj liab thiab lwm yam khoom yuav muab ntxiv kom tau zoo corrosion kuj.
(2) Intergranular corrosion.
Ferritic stainless hlau, zoo li austenitic stainless hlau, raug kev txom nyem los ntawm intergranular corrosion, tab sis kev kho mob thiab kev kho cua sov kom tsis txhob muaj qhov corrosion yog qhov txawv. Ferritic stainless hlau yog feem ntau cuam tshuam rau intergranular corrosion los ntawm ceev txias tshaj 925 ° C, thiab lub xeev (sensitized xeev) uas yog cuam tshuam rau intergranular corrosion yuav raug tshem tawm tom qab ib tug luv luv lub sij hawm ntawm tempering ntawm 650-815 ° C. Lub intergranular corrosion ntawm ferritic hlau kuj yog qhov tshwm sim ntawm chromium depletion los ntawm carbide nag lossis daus. Yog li ntawd, txo cov ntsiab lus ntawm carbon thiab nitrogen hauv cov hlau thiab ntxiv cov ntsiab lus xws li titanium thiab niobium tuaj yeem txo qhov cuam tshuam rau intergranular corrosion.
(3) Pitting thiab crevice corrosion.
Chromium thiab molybdenum yog cov ntsiab lus zoo tshaj plaws los txhim kho pitting thiab crevice corrosion kuj ntawm stainless hlau. Raws li cov ntsiab lus chromium nce, cov ntsiab lus chromium hauv oxide zaj duab xis kuj nce, thiab cov tshuaj lom neeg ruaj khov ntawm cov yeeb yaj kiab nce. Molybdenum yog adsorbed rau ntawm cov hlau ua haujlwm nyob rau hauv daim ntawv ntawm MoO4, uas inhibits kev tawg ntawm cov hlau, txhawb kev rov ua dua, thiab tiv thaiv kev puas tsuaj ntawm zaj duab xis. Yog li ntawd, siab chromium thiab molybdenum ferritic stainless hlau muaj zoo heev tiv taus pitting thiab crevice corrosion.
(4) Ua rau kev ntxhov siab corrosion tawg.
Vim yog cov yam ntxwv ntawm lub koom haum cov qauv, ferritic stainless hlau yog corrosion-resistant nyob rau hauv nruab nrab qhov twg austenitic stainless hlau tsim kev ntxhov siab corrosion cracking.
Mechanical zog ntawm ferritic stainless hlau
Ferritic stainless hlau tsis tuaj yeem muaj zog los ntawm kev kho cua sov vim tias tsis muaj theem hloov pauv. Feem ntau, nws yog siv tom qab annealing ntawm 700-800 ° C. Vim tias qhov loj me me ntawm cov hlau thiab chromium zoo sib xws, cov khoom siv dag zog muaj zog me me, lub zog tawm los thiab tensile lub zog ntawm ferritic stainless hlau yog me ntsis siab dua li cov hlau tsis muaj carbon steel, thiab cov ductility yog qis dua li cov hlau tsis muaj carbon tsawg. .
1) Chav kub brittleness ntawm zoo tib yam ferritic stainless hlau.
Ordinary ferritic stainless hlau yog rhiab heev rau notches, thiab lub nkig hloov kub yog siab tshaj chav tsev kub tshwj tsis yog rau tsawg-chromium ferritic stainless hlau. Qhov siab dua cov ntsiab lus chromium, qhov txias brittleness ntau dua. Qhov txias brittleness no muaj feem xyuam rau cov ntsiab lus interstitial xws li carbon thiab nitrogen nyob rau hauv cov hlau, thiab ultra-ntshiab ferritic steel muaj cov pa roj carbon tsawg heev nyob rau hauv cov ntsiab lus interstitial xws li carbon thiab nitrogen, yog li nws muaj peev xwm tau txais zoo toughness, thiab lub brittle hloov. qhov kub thiab txias tuaj yeem txo qis hauv chav tsev kub.
2) Kub kub embrittlement ntawm zoo tib yam ferritic stainless hlau.
Ordinary ferritic stainless hlau yog rhuab mus rau saum 927 ° C thiab tom qab ntawd txias txias rau hauv chav tsev kub, lub plasticity thiab toughness yog txo. Qhov kub-kub embrittlement no muaj feem xyuam rau cov nag lossis daus ntawm cov pa roj carbon (nitride) cov tebchaw ntawm cov ciam teb lossis kev txav ntawm qhov kub ntawm 427-927 ° C. Txo cov pa roj carbon thiab nitrogen cov ntsiab lus ntawm cov hlau (siv ultra-ntshiab thev naus laus zis) tuaj yeem txhim kho qhov brittleness. Tsis tas li ntawd, thaum cov hlau ferritic tau kub siab tshaj 927 ° C, lub peev xwm ntawm cov nplej yuav coarsened, thiab coarse grain yuav deteriorate lub plasticity thiab toughness ntawm cov hlau.
3) Kev tsim ntawm σ-theem.
Raws li cov hlau-chromium theem daim duab, thaum khaws cia ntawm 500-800 ° C, cov hlau uas muaj 40%-50% chromium yuav tsim ib theem σ, thiab cov hlau uas muaj tsawg dua 20% lossis ntau dua 70% chromium yuav tsim. ib qho α + σ dual-theem qauv. Kev tsim ntawm σ-theem yuav txo qhov ductility thiab toughness ntawm hlau. Yog li, ferritic stainless hlau yuav tsum tsis txhob siv rau lub sijhawm ntev ntawm 500-800 ° C.
4) brittleness ntawm 475 ° C.
High chromium (> 15%) ferritic steel yuav muaj zog embrittled thaum khaws cia ntawm 400-500 ° C. Hom embrittlement no siv sijhawm luv dua li nag lossis daus ntawm σ theem. Piv txwv li, thaum 0.080C-0.4Si-16.9Cr ferritic stainless hlau yog khaws cia ntawm 450 ° C rau 4 teev, chav tsev kub cuam tshuam toughness yuav luag poob rau xoom. Lub degree ntawm embrittlement nce nrog nce ntawm chromium cov ntsiab lus, tab sis lub toughness yuav rov qab tau tom qab kev kho mob siab tshaj 600 ° C. Embrittlement ntawm 475 ° C yog tshwm sim los ntawm nag lossis daus ntawm chromium-nplua nuj alpha theem. Xws li cov hlau yuav tsum tsis txhob cua sov ze 475 ° C.
Post lub sij hawm: May-02-2023