Stainless hlau muaj ob qhov kev faib tawm: ib qho yog muab faib ua chromium stainless hlau thiab chromium nickel stainless hlau raws li cov yam ntxwv ntawm cov ntsiab lus alloy; Lwm qhov yog muab faib ua m stainless hlau, f stainless hlau, stainless hlau thiab AF duplex stainless hlau raws li lub microstructure ntawm hlau nyob rau hauv lub xeev normalized.
1, Martensitic stainless hlau
Hom martensitic stainless hlau muaj xws li 1cr13 ~ 4cr13 thiab 9Cr18
1Cr13 steel muaj kev ua haujlwm zoo. Sib sib zog nqus kos duab, khoov, crimping thiab vuam tuaj yeem nqa tawm yam tsis muaj preheating. 2Crl3 tsis tas yuav tsum tau preheating ua ntej txias deformation, tab sis yuav tsum tau preheating ua ntej vuam. 1Crl3 thiab 2Cr13 feem ntau yog siv los ua cov txheej txheem corrosion-resistant xws li turbine hniav, thaum 3Cr13 thiab 4Cr13 feem ntau yog siv los ua cov cuab yeej kho mob, riam phais thiab qhov hnav-tiv taus; 9crl8 tuaj yeem siv los ua cov kabmob tiv thaiv corrosion thiab cov cuab yeej txiav.
2, Ferritic stainless hlau
Cov ntsiab lus Cr ntawm ferritic stainless hlau feem ntau yog 13 feem pua - 30 feem pua, thiab cov ntsiab lus carbon tsawg dua 0.25 feem pua. Qee zaum lwm cov ntsiab lus alloying ntxiv. Cov qauv metallographic feem ntau yog ferrite, uas tsis pom thaum cua sov thiab txias<=& gt;="" γ="" transformation="" cannot="" be="" strengthened="" by="" heat="" treatment.="" strong="" oxidation="" resistance.="" at="" the="" same="" time,="" it="" also="" has="" good="" hot="" workability="" and="" certain="" cold="" workability.="" ferritic="" stainless="" steel="" is="" mainly="" used="" to="" make="" components="" with="" high="" corrosion="" resistance="" and="" low="" strength="" requirements.="" it="" is="" widely="" used="" to="" manufacture="" equipment="" such="" as="" nitric="" acid="" and="" nitrogen="" fertilizer="" and="" pipelines="" used="" in="" chemical="">
Hom ferritic stainless hlau yog Crl7, Cr25 thiab Cr28.
3, Austenitic stainless hlau
Austenitic stainless hlau yog tsim los kov yeej qhov tsis muaj corrosion kuj thiab brittleness ntawm martensitic stainless hlau. Lub hauv paus muaj pes tsawg leeg yog crl8 feem pua thiab Ni8 feem pua, uas yog abbreviated li 18-8 steel. Nws cov yam ntxwv yog tias cov ntsiab lus carbon tsawg dua 0.1 feem pua, thiab cov qauv austenite ib zaug tau txais los ntawm kev sib xyaw ntawm Cr thiab Ni.
Austenitic stainless hlau feem ntau yog siv los tsim cov khoom siv tshuaj lom neeg xws li nitric acid thiab sulfuric acid, cov khoom siv kub qis hauv kev lag luam tub yees, thiab tuaj yeem siv los ua stainless hlau springs thiab moos tom qab deformation ntxiv dag zog.
Austenitic stainless hlau muaj zoo zoo corrosion kuj, tab sis cov teeb meem nram qab no tseem muaj nyob rau hauv lub zos corrosion kuj:
1. Intergranular corrosion ntawm austenitic stainless hlau
Austenitic stainless hlau yuav tshwm sim intergranular corrosion thaum nws khaws cia sov ntawm 450 ~ 850 degree lossis txias maj mam. Qhov siab dua cov ntsiab lus carbon, ntau dua qhov nyiam ntawm intergranular corrosion. Tsis tas li ntawd, intergranular corrosion kuj tshwm sim nyob rau hauv lub tshav kub cuam tshuam cheeb tsam ntawm weldment. Qhov no yog vim nag lossis daus ntawm Cr nplua nuj Cr23C6 ntawm thaj tsam lis. Qhov chaw tsis zoo chromium yog tsim nyob rau hauv ib puag ncig matrix, uas yog tshwm sim los ntawm corrosion ntawm thawj cell. Qhov no intergranular corrosion tshwm sim kuj muaj nyob rau hauv ferritic stainless hlau hais saum toj no.
Cov hauv qab no feem ntau siv hauv engineering los tiv thaiv intergranular corrosion:
(1) Txo cov pa roj carbon ntsiab lus hauv cov hlau, kom cov ntsiab lus carbon hauv cov hlau qis dua li cov saturated solubility nyob rau hauv austenite nyob rau hauv equilibrium, uas yog, fundamentally daws cov teeb meem ntawm chromium carbide (Cr23C6) nag lossis daus nyob rau hauv grain ciam teb. Feem ntau, qhov yuav tsum tau ua ntawm intergranular corrosion kuj tuaj yeem ua tau raws li cov ntsiab lus carbon hauv cov hlau raug txo kom tsawg dua 0.03 feem pua.
(2) Ntxiv Ti, Nb thiab lwm cov ntsiab lus uas tuaj yeem tsim cov carbides ruaj khov (tic lossis NBC) kom tsis txhob muaj nag lossis daus ntawm Cr23C6 ntawm cov ciam teb tuaj yeem tiv thaiv kev cuam tshuam ntawm intergranular corrosion ntawm austenitic stainless hlau.
(3) Los ntawm kev kho qhov sib piv ntawm austenite tsim cov ntsiab lus rau ferrite tsim cov ntsiab lus hauv cov hlau, nws muaj austenite ntxiv rau ferrite dual theem qauv, uas ferrite suav txog 5 feem pua rau 12 feem pua. Cov qauv dual theem no tsis yooj yim los tsim intergranular corrosion.
(4) Cov txheej txheem kev kho cua sov kom zoo tuaj yeem tiv thaiv intergranular corrosion thiab tau zoo corrosion kuj.
2. Kev nyuaj siab corrosion ntawm austenitic stainless hlau
Kev sib tsoo tshwm sim los ntawm kev sib xyaw ua ke ntawm kev ntxhov siab (feem ntau tensile stress) thiab corrosion yog hu ua stress corrosion cracking (SCC). Austenitic stainless hlau yog qhov yooj yim rau kev ntxhov siab corrosion hauv corrosive media uas muaj chloride ions. Thaum cov ntsiab lus Ni nce mus txog 8 feem pua rau 10 feem pua, qhov kev ntxhov siab corrosion ntawm austenitic stainless hlau yog loj. Txuas ntxiv kom nce Ni cov ntsiab lus mus rau 45 ~ 50 feem pua, thiab kev ntxhov siab corrosion maj mam txo kom txog thaum nws ploj mus.
Txoj hauv kev tseem ceeb los tiv thaiv kev ntxhov siab ntawm austenitic stainless hlau yog ntxiv si2 ~ 4 feem pua thiab tswj cov ntsiab lus N hauv qab no 0.04 feem pua ntawm smelting. Tsis tas li ntawd, cov ntsiab lus ntawm impurities xws li P, Sb, Bi thiab raws li yuav tsum tau txo qis. Tsis tas li ntawd, AF dual-theem steel tuaj yeem xaiv tau, uas yog qhov tsis hnov tsw rau kev ntxhov siab corrosion hauv cl- thiab oh media. Thaum thawj micro tawg ua tau raws li theem ferrite, nws yuav tsis txuas ntxiv, thiab cov ntsiab lus ferrite yuav tsum yog li 6 feem pua.
3. Deformation ntxiv dag zog ntawm austenitic stainless hlau
Ib theem austenitic stainless hlau muaj qhov zoo txias deformation kev ua tau zoo, uas tuaj yeem txias tau kos rau hauv cov hlau zoo heev thiab txias dov rau hauv cov hlau nyias nyias lossis cov yeeb nkab steel. Tom qab ib tug loj npaum li cas ntawm deformation, lub zog ntawm steel yog zoo heev, tshwj xeeb tshaj yog thaum dov nyob rau hauv lub subzero kub cheeb tsam. Lub zog tensile tuaj yeem ncav cuag ntau dua 2000 MPa. Qhov no yog vim hais tias ntxiv rau qhov txias ua hauj lwm hardening nyhuv, deformation induced m transformation yog superimposed.
Austenitic stainless steel can be used to make stainless springs, clocks and clocks, steel ropes in aviation structures, etc. after deformation strengthening. If welding is required after deformation, spot welding process and deformation can only be used to increase the tendency of stress corrosion. Causal part γ->Ferromagnetism tshwm sim los ntawm M transformation yuav tsum tau txiav txim siab nyob rau hauv kev siv (xws li nyob rau hauv ntsuas qhov chaw).
Qhov kub ntawm recrystallization hloov nrog qhov sib txawv deformation. Thaum lub deformation kuj sib txawv yog 60 feem pua, qhov recrystallization kub poob mus rau 650 degree, thiab lub recrystallization annealing kub ntawm txias deformed austenitic stainless hlau yog 850 ~ 1050 degree. Ntawm 850 degree, nws yuav tsum tau sov so rau 3h, thiab tom qab ntawd hlawv tag nrho ntawm 1050 degree, thiab tom qab ntawd dej txias.
4. Kev kho cua sov ntawm austenitic stainless hlau
Cov txheej txheem kev kho cua sov feem ntau ntawm austenitic stainless hlau suav nrog: kev kho tshuaj, kev kho kom ruaj khov thiab kho kev ntxhov siab.
(1) Kev daws teeb meem. Lub hom phiaj tseem ceeb ntawm dej quenching tom qab cua sov cov hlau mus rau 1050 ~ 1150 degree yog kom yaj cov carbides nyob rau hauv austenite thiab ua kom lub xeev no nyob rau hauv chav tsev kub, thiaj li hais tias corrosion kuj ntawm cov hlau yuav zoo heev. Raws li tau hais los saum toj no, txhawm rau tiv thaiv kev cuam tshuam ntawm intercrystalline, cov khoom siv kho mob feem ntau yog siv los yaj Cr23C6 hauv austenite, thiab tom qab ntawd txias txias. Cov cua txias tuaj yeem siv rau cov phab ntsa nyias nyias, thiab dej txias feem ntau yog siv.
(2) Kev kho kom ruaj khov. Feem ntau, nws yog nqa tawm tom qab cov khoom siv kho mob, uas feem ntau yog siv rau 18-8 steel uas muaj Ti thiab Nb. Tom qab kev kho mob, cov hlau yog rhuab mus rau 850 ~ 880 degree thiab ces cua txias. Lub sijhawm no, cov carbides ntawm Cr yog yaj tag, thaum cov carbides ntawm titanium tsis yaj tag, thiab lawv tau tag nrho precipitated thaum lub sij hawm txias, kom cov carbon tsis tuaj yeem tsim chromium carbides dua, yog li cov intergranular corrosion yog zoo tshem tawm.
(3) Kev kho kev ntxhov siab. Kev kho kev ntxhov siab yog kev kho cua sov kom tshem tawm cov kev ntxhov siab ntawm cov hlau tom qab ua haujlwm txias lossis vuam. Feem ntau, nws yog rhuab mus rau 300 ~ 350 degree rau tempering. Rau cov hlau tsis muaj kev ruaj ntseg Ti thiab Nb, cov cua kub kub yuav tsum tsis pub tshaj 450 degree, thiaj li tsis txhob muaj nag lossis daus ntawm chromium carbides thiab intergranular corrosion. Rau kev ua haujlwm txias thiab welded qhov chaw ntawm ultra-low carbon thiab stainless hlau uas muaj Ti thiab Nb, lawv yuav tsum tau rhuab ntawm 500 ~ 950 degree, thiab ces maj mam txias kom tshem tawm kev ntxhov siab (lub siab txwv kub yog npaum li cas rau tshem tawm ntawm vuam kev nyuaj siab. ), uas tuaj yeem txo qhov nyiam ntawm intergranular corrosion thiab txhim kho kev ntxhov siab corrosion ntawm hlau.
4, AUSTENITIC FERRITIC duplex stainless hlau
Raws li lub hauv paus ntawm austenitic stainless hlau, duplex qauv nrog austenite thiab ferrite (muaj 40 ~ 60 feem pua) tuaj yeem tau txais los ntawm qhov tsim nyog nce Cr cov ntsiab lus thiab txo cov ntsiab lus Ni, ua ke nrog kev kho remelting δ- Ferritic ) stainless hlau, cov qib steel raug yog 0cr21ni5ti, 1Cr21Ni5Ti, ocr21ni6mo2ti, thiab lwm yam. Duplex stainless hlau muaj weldability zoo, tsis xav tau kev kho cua sov tom qab vuam, thiab nws nyiam intergranular corrosion thiab kev nyuaj siab corrosion kuj me me. Txawm li cas los xij, vim yog cov ntsiab lus Cr siab, nws yooj yim rau daim ntawv σ Them mloog thaum siv.