Q: Peb nyuam qhuav pib ua qee yam haujlwm uas xav tau qee yam khoom siv los ua los ntawm 304 stainless hlau, uas yog welded rau nws tus kheej thiab rau cov hlau tsis muaj zog. Peb tau ntsib qee qhov teeb meem nrog kev tawg ntawm cov hlau tsis xeb thiab stainless hlau txog li 1.25 ″ tuab. Nws tau hais tias peb muaj cov qib ferrite qis. Koj puas tuaj yeem piav qhia nws yog dab tsi thiab yuav kho nws li cas?
A: Yog ib lo lus nug zoo. Yog, peb tuaj yeem pab koj nkag siab txog lub ntsiab lus ntawm ferrite qis thiab yuav ua li cas tiv thaiv nws.
Ua ntej, cia peb saib lub ntsiab lus ntawm stainless hlau (SS) thiab ferrite cuam tshuam li cas rau cov pob qij txha welded. Cov hlau dub thiab cov hlau sib xyaw muaj ntau dua 50% hlau. Qhov no suav nrog txhua cov hlau carbon thiab stainless hlau, nrog rau qee pawg lwm yam. Txhuas, tooj liab, thiab titanium tsis muaj hlau, yog li lawv yog cov piv txwv zoo ntawm cov hlau sib xyaw uas tsis yog ferrous.
Cov khoom tseem ceeb ntawm cov hlau no yog cov hlau carbon nrog cov hlau tsawg kawg yog 90% thiab cov hlau tsis xeb nrog cov hlau tsawg kawg yog 70 txog 80%. Yuav kom raug cais ua SS, nws yuav tsum muaj tsawg kawg yog 11.5% chromium ntxiv. Cov theem Chromium siab dua qhov tsawg kawg nkaus no txhawb kev tsim cov zaj duab xis chromium oxide ntawm cov hlau thiab tiv thaiv kev tsim cov oxidation xws li xeb (hlau oxide) lossis tshuaj lom neeg xeb.
Cov hlau tsis xeb feem ntau muab faib ua peb pawg: austenitic, ferritic thiab martensitic. Lawv lub npe los ntawm cov qauv siv lead ua ntawm chav tsev kub uas lawv tau tsim. Lwm pawg feem ntau yog duplex stainless hlau, uas yog qhov sib npaug ntawm ferrite thiab austenite hauv cov qauv siv lead ua.
Cov qib Austenitic, 300 series, muaj 16% txog 30% chromium thiab 8% txog 40% nickel, tsim cov qauv siv lead ua austenitic feem ntau. Cov khoom ruaj khov xws li nickel, carbon, manganese, thiab nitrogen raug ntxiv thaum lub sijhawm ua hlau los pab tsim qhov sib piv ntawm austenite-ferrite. Qee cov qib uas siv ntau yog 304, 316 thiab 347. Muab kev tiv thaiv corrosion zoo; feem ntau siv rau hauv kev lag luam khoom noj, tshuaj lom neeg, tshuaj thiab cryogenic. Kev tswj hwm ntawm kev tsim ferrite muab kev tawv zoo heev ntawm qhov kub qis.
Ferritic SS yog qib 400 series uas muaj hlau nplaum tag nrho, muaj 11.5% txog 30% chromium, thiab muaj cov qauv siv lead ua ferritic feem ntau. Txhawm rau txhawb kev tsim cov ferrite, cov stabilizers suav nrog chromium, silicon, molybdenum thiab niobium thaum lub sijhawm tsim hlau. Cov hom SS no feem ntau siv rau hauv cov tshuab tso pa tawm hauv tsheb thiab cov tshuab fais fab thiab muaj kev siv kub tsawg. Ntau hom siv feem ntau: 405, 409, 430 thiab 446.
Cov qib Martensitic, tseem hu ua 400 series, xws li 403, 410, thiab 440, yog sib nqus, muaj 11.5% txog 18% chromium, thiab muaj cov qauv siv lead ua martensitic. Kev sib xyaw ua ke no muaj cov kub qis tshaj plaws, ua rau lawv pheej yig tshaj plaws los tsim. Lawv muab qee qhov kev tiv thaiv corrosion, lub zog zoo dua, thiab feem ntau siv rau hauv cov tais diav, cov khoom siv kho hniav thiab phais, cov khoom siv ua noj, thiab qee hom cuab yeej.
Thaum koj vuam cov hlau tsis xeb, hom substrate thiab nws daim ntawv thov hauv kev pabcuam yuav txiav txim siab seb cov hlau filler twg tsim nyog siv. Yog tias koj siv cov txheej txheem roj tiv thaiv, koj yuav tsum tau them sai sai rau cov roj tiv thaiv sib xyaw kom tiv thaiv qee qhov teeb meem cuam tshuam nrog kev vuam.
Yuav kom soldered 304 rau nws tus kheej, koj yuav tsum tau ib lub electrode E308/308L. "L" sawv cev rau cov pa roj carbon tsawg, uas pab tiv thaiv kev xeb intergranular. Cov pa roj carbon ntawm cov electrodes no tsawg dua 0.03%, yog tias tus nqi no tshaj qhov no, qhov kev pheej hmoo ntawm cov pa roj carbon tso rau ntawm cov ciam teb ntawm cov noob thiab chromium bonding los ua chromium carbides nce, uas ua rau txo qhov kev tiv thaiv xeb ntawm cov hlau. Qhov no yuav pom tseeb yog tias xeb tshwm sim hauv thaj chaw kub-cuam tshuam (HAZ) ntawm cov hlau tsis xeb. Lwm qhov kev xav rau qib L stainless hlau yog tias lawv muaj lub zog tensile qis dua ntawm qhov kub ua haujlwm siab dua li qib stainless hlau ncaj.
Vim tias 304 yog hom hlau stainless austenitic, cov hlau vuam sib xws yuav muaj feem ntau ntawm austenite. Txawm li cas los xij, lub electrode nws tus kheej yuav muaj ferrite stabilizer, xws li molybdenum, los txhawb kev tsim ntawm ferrite hauv cov hlau vuam. Cov chaw tsim khoom feem ntau teev cov ntau yam rau qhov ntau ntawm ferrite rau cov hlau vuam. Raws li tau hais ua ntej, carbon yog lub zog austenitic stabilizer thiab rau cov laj thawj no nws yog qhov tseem ceeb kom tiv thaiv nws ntxiv rau cov hlau vuam.
Cov lej Ferrite yog muab los ntawm daim ntawv qhia Scheffler thiab daim ntawv qhia WRC-1992, uas siv cov qauv sib npaug nickel thiab chromium los xam tus nqi uas thaum kos rau ntawm daim ntawv qhia muab tus lej normalized. Tus lej ferrite ntawm 0 thiab 7 sib raug rau feem pua ​​​​​​ntawm cov qauv siv lead ua ferritic uas muaj nyob hauv cov hlau vuam, txawm li cas los xij, ntawm cov feem pua ​​​​​​siab dua, tus lej ferrite nce ntxiv sai dua. Nco ntsoov tias ferrite hauv SS tsis zoo ib yam li cov hlau carbon ferrite, tab sis ib theem hu ua delta ferrite. Austenitic stainless hlau tsis dhau qhov kev hloov pauv theem cuam tshuam nrog cov txheej txheem kub siab xws li kev kho cua sov.
Kev tsim Ferrite yog qhov xav tau vim tias nws yooj ywm dua li austenite, tab sis yuav tsum tau tswj hwm. Cov ntsiab lus ferrite qis tuaj yeem muab cov vuam nrog kev tiv thaiv corrosion zoo heev hauv qee qhov kev siv, tab sis lawv yooj yim heev rau kev tawg kub thaum lub sijhawm vuam. Rau kev siv dav dav, tus lej ntawm ferrites yuav tsum nyob nruab nrab ntawm 5 thiab 10, tab sis qee qhov kev siv yuav xav tau tus nqi qis dua lossis siab dua. Ferrites tuaj yeem kuaj xyuas tau yooj yim hauv chaw ua haujlwm nrog lub cim qhia ferrite.
Txij li thaum koj hais tias koj muaj teeb meem nrog kev tawg thiab qis ferrites, koj yuav tsum saib ze rau koj cov hlau filler thiab xyuas kom meej tias nws tsim cov ferrites txaus - kwv yees li 8 yuav tsum ua qhov ua kom yuam kev. Tsis tas li ntawd, yog tias koj siv flux-cored arc welding (FCAW), cov hlau filler no feem ntau siv cov pa roj shield ntawm 100% carbon dioxide lossis sib tov ntawm 75% argon thiab 25% CO2, uas tuaj yeem ua rau cov hlau weld nqus cov carbon. Koj tuaj yeem hloov mus rau cov txheej txheem hlau arc welding (GMAW) thiab siv 98% argon / 2% oxygen sib tov los txo qhov ua tau ntawm cov pa roj carbon deposits.
Thaum vuam cov hlau tsis xeb rau cov hlau carbon, yuav tsum siv cov khoom siv E309L. Cov hlau no yog siv tshwj xeeb rau kev vuam hlau sib txawv, tsim ib qho nyiaj ntawm ferrite tom qab cov hlau carbon yaj hauv qhov vuam. Vim tias cov hlau carbon nqus qee cov carbon, ferrite stabilizers raug ntxiv rau cov hlau kom tiv thaiv qhov kev nyiam ntawm cov carbon los tsim austenite. Qhov no yuav pab tiv thaiv kev tawg thermal thaum vuam.
Xaus lus, yog tias koj xav kho cov kab nrib pleb kub hauv cov hlau stainless hlau austenitic welds, xyuas seb puas muaj cov hlau ferrite filler txaus thiab ua raws li kev xyaum vuam zoo. Tswj cov cua sov nkag hauv qab 50 kJ / hauv, tswj qhov kub nruab nrab mus rau qis qis, thiab xyuas kom meej tias cov pob qij txha solder huv si ua ntej soldering. Siv lub ntsuas tsim nyog los xyuas qhov ntau ntawm ferrite ntawm qhov vuam, lub hom phiaj rau 5-10.
WELDER, yav tas los hu ua Practical Welding Today, sawv cev rau cov neeg tiag tiag uas ua cov khoom uas peb siv thiab ua haujlwm nrog txhua hnub. Phau ntawv xov xwm no tau pab cov zej zog vuam hauv North America tau ntau tshaj 20 xyoo.
Tam sim no nrog kev nkag mus rau tag nrho cov ntawv digital ntawm The FABRICATOR, yooj yim nkag mus rau cov peev txheej muaj txiaj ntsig hauv kev lag luam.
Cov ntawv xov xwm digital ntawm The Tube & Pipe Journal tam sim no nkag tau tag nrho, muab kev nkag mus tau yooj yim rau cov peev txheej muaj txiaj ntsig hauv kev lag luam.
Tau txais kev nkag mus rau STAMPING Journal tag nrho, uas muaj cov thev naus laus zis tshiab, cov kev coj ua zoo tshaj plaws thiab xov xwm kev lag luam rau kev lag luam hlau stamping.
Tam sim no nrog kev nkag mus rau The Fabricator en Español tag nrho, koj muaj kev nkag mus rau cov peev txheej muaj txiaj ntsig zoo hauv kev lag luam.