Q1: Nyob rau hauv ib puag ncig carburizing furnace, yog vim li cas Incoloy 800 (UNS N08800) nyiam cov khoom siv rau fixtures, daim phiaj, thiab pas nrig pivrau tus qauv austenitic stainless hlau zoo li 310 lossis 314?
A: Nyob rau hauv cov huab cua carburizing, cov txheej txheem xaiv hloov los ntawm yooj yim oxidation tsis kam mus rau carburization kuj thiab thermal stability. Incoloy 800 outperforms standard heat-resistant stainless steels vim nws qhov sib npaug ntawm npib tsib xee, chromium, thiab hlau.
Lub Failure Mechanism nyob rau hauv Standard Stainless Steels:
Hauv cov huab cua carburizing (cov pa roj carbon ntau ntawm qhov kub siab, feem ntau 870-980℃lossis 1600-1800℃F), cov pa roj carbon diffuses mus rau hauv cov hlau. Hauv cov qauv stainless hlau zoo li 310 (25% Cr, 20% Ni):
Carbide Tsim: Cov pa roj carbon reacts nrog chromium los tsim cov chromium carbide loj (Cr₂₃C₆) hauv cov nplej thiab ntawm cov ciam teb.
Chromium Depletion: Qhov no depletes lub matrix ntawm dawb chromium, txo corrosion thiab oxidation kuj.
Embrittlement: Lub carbide network ua rau cov khoom nkig, ua rau tawg nyob rau hauv thermal thiab mechanical stress.
"Metal Dusting" Vulnerability: Hauv qee qhov xwm txheej, qhov carburization no ua rau muaj kev puas tsuaj loj heev hu ua hlau plua plav.
Vim li cas Incoloy 800 Excels:
Cov ntsiab lus siab nickel (30-35%): Nickel muaj solubility tsawg thiab diffusivity rau carbon. Cov ntsiab lus siab nickel ua raws li kev thaiv, txo qis tus nqi uas carbon tuaj yeem nkag mus rau hauv cov hlau.
Balanced Chromium (19-23%): Txawm hais tias chromium tuaj yeem tsim cov carbides, cov ntsiab lus nickel siab ua kom ntseeg tau tias txawm tias carbides tsim, lawv tsis tas mus li thiab tsis muaj kev puas tsuaj. Cov chromium kuj tseem muaj cov txheej txheem tiv thaiv oxide uas ua rau cov pa roj carbon ingress qeeb.
Stable Austenitic Structure: Tsis zoo li cov hlau ferritic, cov qauv austenitic ntawm Alloy 800 tseem tawv thiab tawv txawm tias tom qab ntev - lub sij hawm raug, muab cov nag lossis daus ntau tshaj carbide tswj.
Rau cov pas nrig txhawb nqa hnyav hauv qhov cub carburizing, qhov no txhais tau tias Incoloy 800 tuav nws cov khoom thauj -cov kabmob muaj peev xwm thiab tiv thaiv kev sib tsoo thiab tawg ntev dua li cov qauv cua sov- tiv taus stainless hlau.
Q2: Tus neeg teb xov tooj cua sov ceeb toom tias Incoloy 800 cov pas nrig txhawb nqa tau dhau los ua nkig thiab sib nqus tom qab ob peb xyoos hauv qhov cub carburizing. Dab tsi yog qhov ua rau metallurgical degradation, thiab cov pas nrig tuaj yeem rov qab tau?
A: Cov tsos mob tau piav qhia -embrittlement thiab kev loj hlob ntawm cov hlau nplaum- yog cov cim qhia ntawm carburization hnyav thiab qhov tshwm sim ntawm kev hloov pauv. Qhov no yog ib qho cim qhia tias cov khoom siv tau mus txog qhov kawg ntawm nws txoj kev pabcuam zoo.
Metallurgical Degradation Mechanism:
Cov pa roj carbon saturation: Ntau xyoo ntawm kev pabcuam, txawm tias nws tsis kam, cov pa roj carbon thaum kawg diffuses tob rau hauv Incoloy 800 rods. Qhov saum npoo ua carburized heev, tsim ib txheej nplua nuj nyob rau hauv chromium carbides.
Chromium Carbide Precipitation: Loj chromium carbides (M₂₃C₆ thiab M₇C₃) precipitate, noj chromium los ntawm matrix.
Matrix Depletion: Kev tshem tawm ntawm chromium los ntawm cov khoom siv tshuaj destabilizes austenitic (lub ntsej muag -centered cubic) qauv.
Ferrite Tsim: Hauv cov pa roj carbon-enriched thiab chromium-depleted aav, cov qauv ruaj khov hloov. Thaum txias los ntawm kev ua haujlwm kub, cov cheeb tsam no tuaj yeem hloov mus rau ferrite (lub cev -centered cubic) lossis martensite. Ferrite thiab martensite yog sib nqus, thaum austenite tsis yog. Yog li ntawd, tus pas nrig ua magnetic.
Embrittlement: Kev sib xyaw ua ke ntawm cov carbide loj ntawm cov ciam teb nplej thiab qhov muaj cov ferrite / martensite theem ua rau cov pas nrig ductility. Nws yuav tawg ntau dua li khoov hauv qab load.
Muaj peev xwm rov qab tau:
Tsis yog, cov pas nrig tsis tuaj yeem rov qab tau. Qhov no yog kev hloov pauv mus tas li microstructural.
Kev kho cua sov tsis muaj txiaj ntsig: Thaum lub siab -kub tshuaj anneal yuav yaj qee cov carbides thiab rov-austenitize tus qauv, nws tsis tuaj yeem tshem tawm cov pa roj carbon ntau dhau. Thaum rov- raug rau qhov kub thiab txias, cov carbides yuav tam sim ntawd rov- nag lossis daus, feem ntau nyob rau hauv ib qho kev faib loj dua.
Kev daws tsuas yog: Cov pas nrig yuav tsum tau hloov. Txhawm rau txuas ntxiv lub neej ntawm cov txheej txheem tshiab, cov neeg ua haujlwm yuav tsum xav txog:
Kev khiav hauj lwm kub qis: Yog ua tau.
Higher Alloy Upgrade: Txav mus rau Alloy 600 (nickel siab dua) los yog Alloy 601 (txhuas- hloov kho kom zoo dua oxide adherence) kom muaj zog carburization ntau dua.
Txheej: Siv cov tshuaj tiv thaiv-carburization coatings (ceramic lossis aluminium- nplua nuj) rau cov pas nrig tshiab.
Q3: Thaum lub sijhawm tu, peb yuav tsum tau txuas tus pas nrig Incoloy 800 tshiab rau ib daim phiaj carburized uas twb muaj lawm. Dab tsi yog qhov tshwj xeeb vuam cov nyom, thiab cov hlau muab tub lim yuav tsum tau siv los xyuas kom muaj kev sib koom ua ke?
A: Vuam ib qho tshiab Incoloy 800 bar rau cov khoom siv carburized uas twb muaj lawm yog ib qho kev kho nyuaj uas muaj kev pheej hmoo loj. Thawj qhov kev sib tw yog cov pa roj carbon tsiv teb tsaws los ntawm cov qub, carburized ib feem rau hauv cov hlau vuam thiab cov pas nrig tshiab.
Cov Kev Sib Tw Welding:
Carbon Pickup: Cov qub, carburized daim phiaj muaj cov pa roj carbon ntau. Thaum lub sij hawm vuam, cua sov los ntawm lub arc tuaj yeem ua rau cov pa roj no yaj thiab txav mus rau hauv lub pas dej molten weld. Qhov no ua rau cov pa roj carbon ntau ntawm cov hlau welding, ua rau nws nyuaj thiab nkig, thiab raug kub kub tawg.
Cov Teeb Meem Dilution: Yog tias lub pas dej weld dilutes ntau dhau ntawm cov qub carburized puag hlau, qhov tshwm sim ntawm cov khoom siv vuam vuam yuav raug tawm, txo nws cov corrosion thiab kub tsis kam.
Lim- Hnub Nyoog Cracking: Lub tshav kub- thaj tsam cuam tshuam (HAZ) ntawm cov khoom qub, carburized tej zaum twb yuav embrittled thiab nquag tawg los ntawm vuam kev nyuaj siab.
Cov txheej txheem pom zoo thiab muab tub lim:
Kev npaj yog qhov tseem ceeb:
Sib tsoo rov qab rau thaj tsam ntawm daim phiaj qub uas yuav ua qhov vuam. Tshem tawm yam tsawg kawg 1-2 hli ntawm carburized nto txheej kom nthuav tawm "tshiab" hlau hauv qab. Qhov no txo cov pa roj carbon ntau rau kev tsiv teb tsaws.
Filler Hlau Xaiv:
Tsis txhob siv cov muab tub lim (piv txwv li, ERNiCr-3). Thaum ERNiCr-3 (Alloy 600 hom muab tub lim) feem ntau yog siv rau vuam Alloy 800, nws tuaj yeem raug cuam tshuam rau cov khoom thauj los ntawm carburized puag hlau.
Cov Filler Pom Zoo: Siv ntau tshaj -alloyed muab tub lim xws li ERNiCrMo-3 (Alloy 625) lossis ERNiCrMo-4 (Alloy C-276).
Yog vim li cas: Cov high-molybdenum, siab- npib tsib xee muab tub lim muaj ntau dua rau cov pa roj carbon thiab impurities. Lawv yog cov ductile ntau dua thiab tiv taus kev tawg, txawm tias qee qhov kev khaws cov pa roj carbon monoxide tshwm sim los ntawm daim phiaj qub carburized.
Vuam Tshuab:
Siv cov khoom siv hluav taws xob tsawg (GTAW/TIG nyiam).
Txo cov dilution los ntawm kev siv cov txheej txheem weaving me ntsis los xyuas kom meej qhov vuam hlau fuses rau ob sab tsis dhau melting cov khoom qub carburized puag.
Khaws qhov kub ntawm qhov sib cuam tshuam qis.
Txawm tias muaj kev ceev faj, hom kev kho no suav tias yog ib ntus. Cov khoom qub carburized yuav txuas ntxiv mus, thiab qhov chaw weld tseem yog qhov tsis muaj zog.
Q4: Tshaj li cov tshuaj muaj pes tsawg leeg, dab tsi zoo hauv kev tsim khoom ntawm Incoloy 800 bar Tshuag yog qhov tseem ceeb rau kev ua haujlwm ntev hauv cov khoom siv carburizing?
A: Rau kev pabcuam carburizing, qhov zoo ntawm cov khoom lag luam bar tsis yog hais txog kev ua kom tau raws li cov tshuaj lom neeg hauv ASTM B408. Ob yam -cov qoob loo loj thiab qhov chaw saum npoo- yog qhov tseem ceeb rau kev ua tau zoo.
1. Grain Size (Qhov "Coarse Grain" Advantage):
Qhov yuav tsum tau muaj: Rau siab - kub carburizing kev pab cuam, ib co coarse grain loj (ASTM Grain Size No. 3 los yog coarser) yog feem ntau teev, ntau npaum li cas zoo grain loj xav tau rau ambient kub zog.
Yog vim li cas: Cov ciam teb nplej yog siab - thaj chaw muaj zog thiab ua raws li txoj kev nrawm nrawm rau cov pa roj carbon (ib qho tshwm sim hu ua grain ciam diffusion). Ib qho ntxhib- cov khoom nplej muaj tsawg dua tag nrho cov qoob loo ciam thaj tsam ntawm ib chav tsev ntim. Qhov no txo txoj hauv kev kom cov pa roj nkag mus tob rau hauv qhov bar.
Cov Specification: Xyuas kom cov bar Tshuag yog muab nyob rau hauv annealed mob nrog ib tug tswj, coarse grain qauv. Qee lub tuam txhab muab "H-qib" (Alloy 800H / HT) uas muaj qhov loj me me thiab muaj zog nkag siab dua.
2. Ntoj yam mob (Qhov yuav tsum tau "Daim tawv nqaij huv"):
Kev pheej hmoo: Txhua qhov chaw tsis xws luag -xws li laps, seams, khawb, lossis decarburization- ua raws li kev ntxhov siab thiab, qhov tseem ceeb tshaj, yog qhov chaw rau cov pa roj carbon ntau ntxiv.
Vim li cas nws tseem ceeb: Hauv carburizing, carbon tawm tsam qhov chaw. Yog hais tias lub bar muaj ib tug ntxhib nto los yog residual nplai los ntawm kub dov uas tsis tau muab tshem tawm kom zoo, qhov chaw zoo rau carburization nce. Qhov tseem ceeb tshaj, cov txheej txheem decarburized (nto depleted ntawm carbon) yog softer thiab tsis muaj zog, thiab thaum carburization pib, nws yuav mus unevenly.
Qhov Ntsuas Qhov Zoo: Siab- cov khoom lag luam zoo rau qhov kev pabcuam no feem ntau tsis muaj qhov nruab nrab lossis tig thiab polished kom tshem tawm tag nrho cov khoom tsis zoo thiab decarburization los ntawm cov txheej txheem ua haujlwm kub. Qhov no muab lub ntsej muag du, zoo ib yam uas tiv thaiv cov pa roj carbon ntau dua.
Q5: Tus tsim qauv yog xaiv ntawm tus qauv Alloy 800 (UNS N08800) thiab Alloy 800HT (UNS N08811) rau ib txheej hnyav -lub luag haujlwm carburizing furnace txhawb nqa rods ua haujlwm ntawm 980℃(1800℃F). Qhov kev txiav txim siab yog dab tsi?
A: Ntawm 980℃(1800℃F), koj nyob ntawm qhov txwv siab tshaj ntawm cov hlau dab tsi -nickel-chromium alloys tuaj yeem ua tau. Qhov kev xaiv ntawm tus qauv Alloy 800 thiab Alloy 800HT hinges ntawm lub load-cov kev cai bearing thiab qhov tshwj xeeb creep kuj xav tau.
Qhov txawv tseem ceeb: Creep Strength
Standard Alloy 800 (N08800): Muaj lub zog zoo tab sis tsis ua kom zoo rau qhov siab tshaj plaws creep kuj. Ntawm 980 degree, nws lub zog creep tej zaum yuav tsis txaus rau cov khoom hnyav hnyav, ua rau maj mam sagging (creep deformation) dhau sijhawm.
Alloy 800HT (N08811 / N08810): Qhov no yog ib qho kev tswj xyuas chemistry ntawm Alloy 800 tshwj xeeb tsim los rau kev pom kev nkag siab zoo. Nws nta:
Cov ntsiab lus Carbon siab dua: Tswj tau rau 0.06-0.10% (piv rau cov pa roj carbon tsawg hauv tus qauv 800).
Tightly Controlled Grain Size: Yuav tsum muaj cov nplej ntxhib loj (ASTM 5 lossis coarser) kom muaj zog tshaj plaws.
Tiag Ti: C Ratio: Yuav tsum muaj qhov tsawg kawg nkaus titanium-rau- Cov pa roj carbon piv (feem ntau 4: 1) kom ntseeg tau tias tag nrho cov pa roj carbon yog khi li TiC ruaj khov, uas ntxiv dag zog rau cov ciam teb thiab tiv thaiv chromium carbide tsim.
Kev txiav txim siab Matrix ntawm 980 degree:
| Qhov xwm txheej | Txheem Alloy 800 (N08800) | Hlau alloy 800HT (N08811) |
|---|---|---|
| Carburization Resistance | Zoo | Zoo (zoo sib xws) |
| Oxidation Resistance | Zoo | Zoo (zoo sib xws) |
| Creep Strength (Load{0}}Bearing) | Nruab nrab | Zoo heev (Superior) |
| Nqi | qis | Siab dua |
| Kev thov kom haum | Lightly loaded kev txhawb nqa, baffles, radiant tubes nrog tsawg txhua yam kev ntxhov siab. | Cov pas nrig txhawb nqa hnyav, cov yob ua haujlwm, kab sib chaws, thiab cov tswv cuab hauv cov khoom siv siab tshaj - qhov cub kub. |
Qhov Kev Txiav Txim:
Yog tias cov pas nrig txhawb nqa tuav qhov hnyav (piv txwv li, pob tawb loj ntawm cov khoom hnyav) ntawm 980 degree, Alloy 800HT yog qhov tsim nyog xaiv. Lub zog creep ntau zog yuav tiv thaiv cov pas nrig los ntawm sagging thiab deforming tshaj cov cuab yeej tsim lub neej. Yog tias cov pas nrig tau maj mam thauj khoom lossis qhov kub thiab txias me ntsis, tus qauv Alloy 800 tuaj yeem txaus, tab sis ntawm 980 degree, tus nqi ntxiv ntawm 800HT feem ntau yog tsim nyog los ntawm lub neej ntev kev pab cuam thiab txo cov txij nkawm.
