Lub vuam yam ntxwv ntawm austenitic stainless hlau: tus nqi ntawm elastic thiab yas kev nyuaj siab thiab strain thaum lub sij hawm vuam yog loj, tab sis txias tawg tsis tshua muaj tshwm sim. Tsis muaj quench hardening cheeb tsam thiab grain coarsening nyob rau hauv lub welded sib koom, yog li lub tensile lub zog ntawm lub welded ob leeg yog siab.
Cov teeb meem tseem ceeb ntawm austenitic stainless hlau vuam: vuam deformation yog loj; vim nws cov yam ntxwv ntawm ciam teb thiab rhiab heev rau tej yam kab mob impurities (S, P), nws yog ib qho yooj yim los tsim kub tawg.
Tsib qhov teeb meem loj vuam ntawm austenitic stainless hlau thiab lawv cov kev daws teeb meem
No1.Qhov tsim ntawm chromium carbide txo qhov tsis kam ntawm welded pob qij txha rau intergranular corrosion.
Intergranular corrosion: Raws li txoj kev xav ntawm cov neeg tsis zoo chromium, thaum lub vuam thiab thaj chaw muaj kev kub ntxhov tau rhuab mus rau 450-850 degree sensitization kub cheeb tsam, chromium carbide yuav precipitate nyob rau hauv grain ciam teb, ua rau lub grain ciam ntawm cov neeg pluag. chromium, uas tsis txaus los tiv thaiv corrosion.
(1) Rau qhov sib txawv corrosion ntawm cov vuam thiab corrosion ntawm qhov kub thiab txias cheeb tsam ntawm cov khoom siv, cov kev ntsuas hauv qab no tuaj yeem siv los txwv:
a. Txo cov pa roj carbon ntsiab lus ntawm lub hauv paus hlau thiab vuam, thiab ntxiv stabilizing cov ntsiab lus Ti, Nb thiab lwm yam ntsiab lus rau lub hauv paus hlau kom nyiam ua MC kom tsis txhob tsim Cr23C6.
b. Ua cov weld tsim dual-theem qauv ntawm austenite thiab me me ntawm ferrite. Thaum muaj qee qhov nyiaj ntawm ferrite nyob rau hauv weld, cov nplej tuaj yeem ua kom zoo dua qub, thaj tsam ntawm cov nplej tuaj yeem nce ntxiv, thiab tus nqi ntawm chromium carbide nag lossis daus ib chav tsev ntawm thaj tsam ntawm cov qoob loo tuaj yeem txo.
Chromium muaj ib qho loj solubility nyob rau hauv ferrite, thiab Cr23C6 yog preferially tsim nyob rau hauv ferrite, tsis ua rau lub austenite grain ciam yuav depleted nyob rau hauv chromium; cov ferrite tawg ntawm austenite tuaj yeem tiv thaiv kev xeb raws li cov ciam teb rau sab hauv diffusion.
c. Tswj lub sijhawm nyob hauv qhov ntsuas kub ntawm qhov ntsuas kub. Kho qhov vuam thermal voj voog kom luv lub sij hawm nyob ntawm 600-1000 degree kom ntau li ntau tau, thiab xaiv ib txoj kev vuam nrog lub zog ceev (xws li ntshav argon arc vuam),
Xaiv ib txoj kab hluav taws xob me me, hla cov roj argon rau sab nraub qaum lossis siv lub ncoo tooj liab txhawm rau ua kom cov cua txias ntawm qhov sib koom ua ke, txo tus naj npawb ntawm arc pib thiab arc xaus kom tsis txhob rov ua cua sov, thiab qhov chaw sib cuag nrog qhov nruab nrab corrosive thaum lub sij hawm ntau txheej vuam yog kom deb li deb tau. Vuam thiab lwm yam.
d. Tom qab welding, nqa tawm kev kho mob los yog stabilization annealing (850-900 degree ) thiab cua txias tom qab tshav kub preservation, thiaj li hais tias cov carbides yuav ua tau tag nrho precipitated thiab diffusion ntawm chromium yuav ceev tau).
(2) Riam zoo li corrosion ntawm cov pob qij txha welded, vim li no, cov kev tiv thaiv hauv qab no tuaj yeem ua tau:
Vim muaj cov pa roj carbon diffusivity muaj zog, nws yuav sib cais ntawm cov ciam teb los ua lub xeev supersaturated thaum lub caij txias, thaum Ti thiab Nb nyob twj ywm hauv cov siv lead ua vim lawv qhov tsis tshua muaj diffusivity. Thaum cov welded sib koom yog rhuab dua nyob rau hauv lub rhiab heev kub ntau yam, cov supersaturated carbon yuav precipitate nyob rau hauv daim ntawv ntawm Cr23C6 nyob rau hauv lub intergranular.
a. Txo cov ntsiab lus carbon. Rau cov hlau stainless uas muaj cov khoom ruaj khov, cov ntsiab lus carbon yuav tsum tsis pub tshaj 0.06%.
b. Siv cov txheej txheem vuam tsim nyog. Xaiv ib qho me me vuam kab hluav taws xob kom txo tau lub sij hawm nyob rau hauv lub overheated cheeb tsam ntawm qhov kub thiab txias, thiab xyuam xim kom tsis txhob muaj cov nyhuv ntawm "qhov nruab nrab kub sensitization" thaum lub sij hawm vuam txheej txheem.
Thaum welding ob tog, lub vuam seam nyob rau hauv kev sib cuag nrog corrosive nruab nrab yuav tsum tau welded kawg (qhov no yog vim li cas vim li cas lub puab vuam ntawm lub loj-inch tuab-walled welded yeeb nkab yog nqa tawm tom qab lub txheej vuam). Qhov chaw overheated nyob rau hauv kev sib cuag nrog corrosive nruab nrab yog dua rhuab los ntawm rhiab heev.
c. Kev kho cua sov tom qab vuam. Kev daws los yog kev kho kom ruaj khov yog nqa tawm tom qab vuam.
Tsis yog 2, Kev ntxhov siab corrosion tawg
Cov kev ntsuas hauv qab no tuaj yeem raug coj los tiv thaiv qhov tshwm sim ntawm kev ntxhov siab corrosion cracking:
a. Kev xaiv cov ntaub ntawv raug thiab tsim nyog hloov ntawm weld muaj pes tsawg leeg. High-purity chromium-nickel austenitic stainless hlau, high-silicon chromium-nickel austenitic stainless hlau, ferritic-austenitic stainless hlau, high-chromium ferritic stainless hlau, thiab lwm yam. Kev ntxhov siab-corrosion kuj yog qhov zoo thaum cov qauv ntawm ob-theem steel yog ferritic thiab ferritic.
b. Tshem tawm lossis txo cov kev ntxhov siab uas seem. Tom qab-weld kev ntxhov siab nyem kev kho cua sov yog ua tiav, thiab cov txheej txheem siv tshuab xws li polishing, txhaj tshuaj peening thiab hammering yog siv los txo qhov seem seem.
c. Tsim nyog tus qauv tsim. kom tsis txhob muaj kev ntxhov siab loj.
No3.Welding kub tawg (weld crystallization tawg, tshav kub cuam tshuam cheeb tsam liquefaction tawg)
Lub thermal crack susceptibility feem ntau yog nyob ntawm cov tshuaj muaj pes tsawg leeg, qauv thiab cov khoom ntawm cov khoom. Ni yog ib qho yooj yim los tsim cov ntsiab lus qis melting point lossis eutectic nrog impurities xws li S thiab P, thiab kev sib cais ntawm boron thiab silicon yuav ua rau thermal tawg.
Lub weld yog ib qho yooj yim los tsim ib coarse columnar grain qauv nrog muaj zog directionality, uas yog conducive rau lub segregation ntawm teeb meem impurities thiab hais. Li no txhawb kev tsim ntawm ib qho txuas ntxiv intercrystalline kua zaj duab xis thiab txhim kho qhov rhiab heev ntawm thermal tawg. Yog hais tias lub vuam yog rhuab unevenly, nws yog ib qho yooj yim los tsim ib tug loj tensile kev nyuaj siab thiab txhawb lub tsim ntawm vuam kub tawg.
Kev tiv thaiv:
a. nruj me ntsis tswj cov ntsiab lus ntawm teeb meem impurities S thiab P.
b. Kho qhov kev ntxhib los mos ntawm cov hlau weld. Cov qauv dual-theem weld muaj qhov ua kom tawg tau zoo. Lub delta theem nyob rau hauv lub weld tuaj yeem kho cov nplej, tshem tawm cov kev taw qhia ntawm ib-theem austenite, txo qhov kev sib cais ntawm cov khoom tsis zoo ntawm cov ciam teb, thiab cov theem delta tuaj yeem yaj ntau S,
P, thiab tuaj yeem txo qhov cuam tshuam lub zog thiab teeb tsa kev tsim ntawm intercrystalline kua zaj duab xis.
c. Kho cov weld hlau alloy muaj pes tsawg leeg. Tsim nyog nce cov ntsiab lus ntawm Mn, C, thiab N nyob rau hauv ib-theem austenitic steel, thiab ntxiv ib qho me me ntawm cov kab mob xws li cerium, pickax, thiab tantalum (uas tuaj yeem kho cov qauv weld thiab purify grain ciam teb) kom txo tau kub tawg. rhiab heev.
d. txheej txheem ntsuas. Txo cov cua sov ntawm lub pas dej molten kom tsis txhob tsim cov coarse columnar crystals, thiab siv cov kab me me zog thiab cov hlaws me me hlaws.
Piv txwv li, hom 25-20 austenitic steels yog qhov ua rau liquefaction tawg. Los ntawm nruj me ntsis txwv cov impurity cov ntsiab lus thiab grain loj ntawm lub hauv paus hlau, txais yuav siab zog welding txoj kev, me me kab zog thiab ua rau cov cua txias ntawm cov pob qij txha thiab lwm yam kev ntsuas.
No4.Embrittlement ntawm welded pob qij txha
Cov hlau kub-lub zog yuav tsum xyuas kom cov yas ntawm cov welded sib koom ua ke thiab tiv thaiv kub kub embrittlement; Qhov kub tsis tshua muaj hlau yuav tsum muaj qhov kub tsis tshua muaj zog kom tiv thaiv qhov kub tsis tshua muaj kev sib txhuam ntawm cov welded sib koom.
No5.Welding deformation loj
Vim tsis muaj thermal conductivity thiab loj expansion coefficient, vuam deformation yog loj, thiab fixture yuav siv tau los tiv thaiv deformation. Vuam txoj kev thiab xaiv cov khoom siv vuam rau austenitic stainless hlau:
Austenitic stainless hlau tuaj yeem welded los ntawm argon tungsten arc vuam (TIG), melting electrode argon arc vuam (MIG), plasma argon arc vuam (PAW) thiab submerged arc vuam (SAW).
Austenitic stainless hlau muaj qhov tsis tshua muaj vuam tam sim no vim nws qhov qis melting point, tsis tshua muaj thermal conductivity thiab siab resistivity. Nqaim welds thiab hlaws dai yuav tsum tau siv los txo qhov kub ntawm qhov chaw nyob, tiv thaiv carbide nag lossis daus, txo cov weld shrinkage kev ntxhov siab, thiab txo cov thermal tawg rhiab heev.
Qhov sib xyaw ntawm vuam consumables, tshwj xeeb tshaj yog cov alloying ntsiab ntawm Cr thiab Ni, yog siab tshaj li ntawm lub hauv paus hlau. Welding consumables uas muaj ib tug me me ({0}}%) ntawm ferrite yog siv los xyuas kom meej zoo tawg kuj (txias cracking, kub tawg, kev nyuaj siab corrosion cracking) ntawm lub weld.
Thaum lub ferrite theem tsis tso cai los yog tsis yooj yim sua nyob rau hauv lub vuam, cov vuam consumables uas muaj Mo, Mn thiab lwm yam alloying ntsiab yuav tsum tau xaiv.
C, S, P, Si, thiab Nb hauv cov khoom siv vuam yuav tsum tsawg li tsawg tau. Nb yuav ua rau cov kab nrib pleb khov nyob rau hauv cov ntshiab austenite welds, tab sis ib qho me me ntawm ferrite hauv cov welds tuaj yeem zam tau zoo.
Rau cov qauv welded uas xav tau kom ruaj khov lossis kev ntxhov siab tom qab vuam, Nb-muaj cov khoom siv vuam feem ntau yog xaiv. Submerged arc vuam yog siv rau vuam nruab nrab daim hlau, thiab qhov kub ntawm Cr thiab Ni tuaj yeem ntxiv los ntawm kev hloov pauv ntawm cov ntsiab lus alloying hauv flux thiab vuam hlau;
Vim yog qhov tob tob tob, kev saib xyuas yuav tsum tau saib xyuas kom tsis txhob muaj kev kub ntxhov nyob rau hauv qhov chaw nruab nrab ntawm cov vuam thiab txo qhov kev tiv thaiv corrosion nyob rau hauv qhov chaw kub-tsim. Kev saib xyuas yuav tsum tau them rau kev xaiv ntawm cov hlau welding thinner thiab me me vuam kab zog, thiab cov vuam hlau yuav tsum tsis tshua muaj Si, S, thiab P.
Cov ntsiab lus ferrite nyob rau hauv lub tshav kub-resistant stainless hlau weld yuav tsum tsis txhob ntau tshaj 5%. Rau austenitic stainless hlau nrog Cr thiab Ni cov ntsiab lus siab tshaj 20%, siab Mn (6-8%) vuam hlau yuav tsum tau siv, thiab alkaline los yog nruab nrab flux yuav tsum tau siv raws li cov flux los tiv thaiv qhov sib ntxiv ntawm Si rau weld. thiab txhim kho nws cov kab nrib pleb.
Qhov tshwj xeeb flux rau austenitic stainless hlau muaj me ntsis Si ntxiv, uas tuaj yeem hloov cov hlau mus rau qhov vuam kom them nyiaj rau qhov kub poob ntawm cov hlau alloy kom tau raws li qhov yuav tsum tau ua ntawm vuam kev ua tau zoo thiab tshuaj muaj pes tsawg leeg.
