Q: Peb nyuam qhuav pib ua qee yam haujlwm uas xav tau qee yam khoom siv ua los ntawm cov hlau tsis xeb qib 304, uas yog welded rau nws tus kheej thiab rau cov hlau tsis muaj zog. Peb tau ntsib qee qhov teeb meem tawg ntawm cov hlau tsis xeb rau cov hlau tsis xeb welds txog li 1.25 ″ tuab. Nws tau hais tias peb muaj cov lej ferrite qis. Koj puas tuaj yeem piav qhia qhov no yog dab tsi thiab yuav kho nws li cas?
A: Qhov no yog ib lo lus nug zoo. Yog, peb tuaj yeem pab koj nkag siab txog lub ntsiab lus ntawm cov lej ferrite qis thiab yuav ua li cas tiv thaiv nws.
Ua ntej, cia peb rov xyuas dua qhov kev txhais ntawm cov hlau tsis xeb (SS) thiab ferrite cuam tshuam li cas rau cov pob qij txha vuam. Cov hlau dub thiab cov hlau sib xyaw muaj ntau dua 50% hlau. Qhov no suav nrog txhua cov hlau carbon thiab stainless hlau thiab lwm pawg txhais. Aluminium, 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 uas muaj tsawg kawg yog 90% hlau thiab SS uas muaj 70 txog 80% hlau. Yuav kom raug cais ua SS, nws yuav tsum muaj tsawg kawg yog 11.5% chromium ntxiv. Cov qib Chromium siab dua qhov tsawg kawg nkaus no txhawb kev tsim cov yeeb yaj kiab chromium oxide ntawm cov hlau thiab tiv thaiv kev tsim oxidation xws li xeb (hlau oxide) lossis xeb los ntawm kev tawm tsam tshuaj lom neeg.
SS feem ntau muab faib ua peb pawg: austenite, ferrite thiab martensite. Lawv lub npe los ntawm cov qauv siv lead ua hauv chav sov uas ua rau lawv. Lwm pawg feem ntau yog duplex SS, 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. Txhawm rau txhawb kev tsim cov piv ntawm austenite-ferrite, cov stabilizers xws li nickel, carbon, manganese thiab nitrogen raug ntxiv thaum lub sijhawm ua hlau. Qee cov qib uas siv ntau yog 304, 316 thiab 347. Muaj kev tiv thaiv corrosion zoo; feem ntau siv rau hauv cov khoom noj, kev pabcuam tshuaj, tshuaj thiab cov ntawv thov cryogenic. Kev tswj hwm ntawm ferrite tsim muab kev tawv zoo heev thaum 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 tseem ceeb. 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 chaw tsim hluav taws xob thiab muaj kev siv kub tsawg. Ntau hom siv feem ntau yog 405, 409, 430 thiab 446.
Cov qib Martensitic, kuj tau txheeb xyuas los ntawm 400 series xws li 403, 410 thiab 440, yog hlau nplaum, muaj 11.5% txog 18% chromium, thiab muaj martensite ua cov qauv siv lead ua. Kev sib xyaw ua ke no muaj cov ntsiab lus kub qis tshaj plaws, uas ua rau lawv pheej yig tshaj plaws los tsim. Lawv muab qee qhov kev tiv thaiv corrosion; lub zog zoo heev; 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 SS, 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 tiv thaiv roj, koj yuav tsum tau them sai sai rau kev tiv thaiv cov roj sib xyaw kom tiv thaiv qee yam teeb meem ntsig txog kev vuam.
Yuav kom soldered 304 rau nws tus kheej, koj yuav tsum tau ib lub electrode E308/308L. Tus "L" sawv cev rau cov pa roj carbon tsawg, uas pab tiv thaiv kev xeb intergranular. Cov electrodes no muaj cov pa roj carbon tsawg dua 0.03%; txhua yam saum toj no ua rau muaj kev pheej hmoo ntawm cov pa roj carbon precipitating rau cov ciam teb ntawm cov noob thiab sib xyaw nrog chromium los ua chromium carbides, 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 hnyiab (HAZ) ntawm SS welded joints. Lwm qhov kev xav rau L qib SS yog tias lawv muaj lub zog tensile qis dua ntawm qhov kub siab dua li qib SS ncaj qha.
Vim tias 304 yog hom SS 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 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 los ntawm kev ntxiv rau cov hlau vuam.
Cov lej Ferrite yog muab los ntawm daim duab Schaeffler thiab daim duab WRC-1992, uas siv cov qauv sib npaug nickel thiab chromium los xam tus nqi, uas thaum kos rau ntawm daim duab tsim cov lej normalized. Tus lej ferrite ntawm 0 thiab 7 sib raug rau qhov ntim feem pua ​​ntawm cov qauv siv lead ua ferrite 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 SS tsis muaj kev hloov pauv theem cuam tshuam nrog cov txheej txheem kub siab xws li kev kho cua sov.
Qhov kev tsim ntawm ferrite yog qhov xav tau vim tias nws yog ductile ntau dua li austenite, tab sis yuav tsum tau tswj hwm. Cov lej ferrite qis tuaj yeem tsim 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 cov xwm txheej siv dav dav, cov lej ferrite yuav tsum nyob nruab nrab ntawm 5 thiab 10, tab sis rau qee qhov kev siv yuav tsum muaj cov nqi qis dua lossis siab dua. Ferrites tuaj yeem txheeb xyuas tau yooj yim ntawm txoj haujlwm siv tus qhia ferrite.
Vim koj hais tias koj muaj teeb meem tawg thiab muaj cov ferrite tsawg, koj yuav tsum saib ze rau koj cov hlau filler thiab xyuas kom meej tias nws tsim cov ferrite txaus - kwv yees li 8 yuav pab tau. Tsis tas li ntawd, yog tias koj siv flux cored arc welding (FCAW), cov hlau filler no feem ntau siv cov roj carbon dioxide shielding 100% lossis 75% argon/25% CO2 sib xyaw, uas tuaj yeem ua rau cov pa roj carbon nqus tau hauv cov hlau weld. Tej zaum koj yuav xav hloov mus rau cov txheej txheem gas metal arc welding (GMAW) thiab siv 98% argon/2% oxygen sib xyaw kom txo qhov ua tau ntawm cov pa roj carbon pickup.
Yuav kom vuam SS rau cov hlau carbon koj yuav tsum siv cov khoom siv E309L filler. Cov hlau filler no yog siv tshwj xeeb rau kev vuam cov hlau sib txawv thiab tsim ib qho nyiaj ntawm ferrite tom qab cov hlau carbon raug diluted rau hauv qhov weld. Vim tias qee cov carbon raug nqus hauv cov hlau carbon, ferrite stabilizers raug ntxiv rau cov hlau filler los tiv thaiv qhov kev nyiam ntawm carbon los tsim austenite. Qhov no yuav pab tiv thaiv kev tawg thermal hauv kev siv vuam.
Hauv kev xaus lus, yog tias koj xav tshem tawm cov kab nrib pleb kub ntawm cov pob qij txha austenitic SS, xyuas kom meej cov hlau ferrite filler txaus thiab ua raws li kev xyaum vuam zoo. Khaws cov cua sov nkag hauv qab 50 kJ / nti, tswj qhov kub nruab nrab mus rau qis qis, thiab xyuas kom meej tias cov pob qij txha solder tsis muaj kev ua qias tuaj ua ntej soldering. Siv lub ntsuas tsim nyog los xyuas kom meej qhov ntau ntawm ferrite ntawm qhov sib koom ua ke, tsom mus rau 5 txog 10.
WELDER, yav tas los hu ua Practical Welding Today, qhia txog 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.
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