1. Q: Dab tsi yog qhov tseem ceeb ntawm kev sib xyaw thiab kev sib txawv ntawm qhov sib txawv ntawm 1.4833 (AISI 309S) thiab 1.4948 (AISI 304H), thiab qhov kev sib txawv no cuam tshuam li cas rau lawv qhov kev ua haujlwm siab - kub?
A:Qhov tseem ceeb sib txawv ntawm 1.4833 thiab 1.4948 nyob rau hauv lawv cov chromium thiab npib tsib xee cov ntsiab lus, uas ncaj qha dictates lawv oxidation tsis kam thiab siab - kub lub zog.
1.4833 (X15CrNiSi20-12), feem ntau hu ua AISI 309S, yog siab -kub austenitic stainless hlau uas muaj kwv yees li 22-24% chromium thiab 12-15% npib tsib xee. Cov ntsiab lus chromium siab, siab dua li qib 304, muab qhov tshwj xeeb oxidation tsis kam. Qhov kev xaiv "S" qhia tias muaj cov pa roj carbon tsawg (feem ntau Tsawg dua lossis sib npaug li 0.08%), uas txo qis carbide nag lossis daus thaum vuam thiab ua kom zoo dua corrosion kuj nyob rau hauv raws li -welded mob. Cov hlau no tshwj xeeb yog tsim los rau kev sib tshuam siab - qhov kub thiab txias kev pabcuam, nrog rau qhov ntsuas kub txog li 980℃(1800℃F). Cov ntsiab lus npib tsib xee siab dua kuj tseem ua rau txhim kho lub zog nkag thiab austenite stability ntawm qhov kub siab.
1.4948 (X6CrNi18-10), los yog AISI 304H, yog siab - carbon variant ntawm tus qauv 304 austenitic stainless hlau. Nws muaj 18-20% chromium thiab 8-10.5% npib tsib xee, nrog rau cov ntsiab lus ntawm cov pa roj carbon monoxide xws li 0.04% mus rau 0.10%. Lub npe "H" txhais tau hais tias "siab carbon," uas yog txhob txwm tshaj tawm los txhim kho siab -kub creep zog. Cov ntsiab lus siab carbon siab tso cai rau nag lossis daus ntawm cov carbides uas ntxiv dag zog rau cov ciam teb thaum lub sijhawm ua haujlwm siab kub. Txawm li cas los xij, tus yam ntxwv zoo ib yam no ua rau 1.4948 muaj kev cuam tshuam ntau dua rau kev hnov mob thiab kev cuam tshuam ntawm intergranular tom qab vuam tshwj tsis yog tias cov tshuaj zoo annealed.
Yog li ntawd, 1.4833 yog cov khoom siv zoo tshaj plaws rau cov kav dej uas cuam tshuam rau cov huab cua oxidizing hnyav dua thiab siab dua qhov kub siab tshaj, xws li cov khoom siv hluav taws xob thiab cov khoom siv hluav taws xob hauv cov hluav taws xob tawg hauv petrochemical. Hauv qhov sib piv, 1.4948 raug xaiv rau cov ntawv thov uas xav tau lub zog nkag siab ntawm qhov nruab nrab qhov siab siab (feem ntau yog 500-800 degree) qhov twg oxidizing ib puag ncig tsis nruj, xws li cov raj superheater hauv lub tshuab hluav taws xob lossis cov kav dej refinery qhov twg tus nqi -kev ua tau zoo thiab nkag siab oxidation yog qhov tseem ceeb tshaj qhov kev txwv ntau tshaj.
2. Q: Nyob rau hauv siab -kub piping daim ntaub ntawv xws li reformer tubes los yog superheater headers, ua li cas lub creep rupture lub zog thiab tso cai rau kev ntxhov siab qhov tseem ceeb (ib ASME Tshooj II, Ntu D) ntawm 1.4948 piv rau cov ntawm 1.4833, thiab dab tsi tsim cuam tshuam tshwm sim los ntawm qhov sib txawv no?
A:Lub creep rupture lub zog thiab tso cai rau kev ntxhov siab qhov tseem ceeb rau ob lub alloys sib txawv heev ntawm qhov kub thiab txias, qhia txog lawv cov kev xav ntawm kev tsim metallurgical.
1.4948 (304H)yog tsim tshwj xeeb rau cov ntawv thov uas creep lub zog yog thawj tsim qauv. Vim nws tswj tau cov ntsiab lus siab dua carbon (0.04–0.10%), nws nthuav tawm lub zog siab tshaj plaws ntawm kev sib tsoo piv rau cov qauv 304 qib thiab, tshwj xeeb, piv rau 1.4833 ntawm qhov kub txog li 650℃(1200℃F). Lub nplua carbide nag lossis daus uas tshwm sim thaum lub sij hawm kev pab cuam pins grain ciam teb, retarding grain ciam swb thiab creep deformation. Raws li ASME Tshooj II, Ntu D, 1.4948 tswj hwm qhov muaj txiaj ntsig kev ntxhov siab ntau dua nyob rau hauv qhov kub ntawm 500-700 degree, ua rau nws qhov kev xaiv zoo tshaj plaws rau superheater thiab reheater tubing hauv fossil roj fais fab nroj tsuag uas muaj kev ntxhov siab nyob rau nruab nrab qhov kub thiab txias yog qhov kev tswj xyuas tsis ua haujlwm.
1.4833 (309S), thaum muaj kev tiv thaiv oxidation zoo heev, feem ntau pom muaj zog qis dua 1.4948 ntawm qhov kub hauv qab 750 degree. Nws qhov tsim kom zoo dua yog tsis nyob rau hauv creep kuj tab sis nyob rau hauv nws lub peev xwm los tiv thaiv scaling thiab tswj cov qauv kev ncaj ncees nyob rau hauv ntau hnyav oxidizing ib puag ncig. Ntawm qhov kub siab tshaj 800 degree, 1.4833 tswj cov khoom siv hluav taws xob zoo qhov twg 1.4948 yuav muaj kev nrawm oxidation thiab hlau poob.
Kev tsim qauv yog qhov tseem ceeb: rau cov kav dej ua haujlwm ntawm 600℃nyob rau hauv siab sab hauv (piv txwv li, 50 bar), 1.4948 feem ntau yuav tso cai rau cov phab ntsa tuab dua vim nws qhov kev cia siab ntau dua, ua rau txo cov khoom hnyav thiab tus nqi. Hloov pauv, rau lub kaw lus ua haujlwm ntawm 900℃hauv ib puag ncig oxidizing flue gas, 1.4833 yuav tsum tsis muaj kev xav txog kev xav, vim 1.4948 yuav raug kev txom nyem los ntawm kev puas tsuaj loj thiab kev poob qis uas ua rau nws lub zog nkag siab zoo tsis cuam tshuam.
3. Q: Dab tsi yog qhov kev txiav txim siab tseem ceeb ntawm kev siv vuam rau 1.4833 thiab 1.4948 seamless kav, tshwj xeeb tshaj yog hais txog kev xaiv hlau muab tub lim, kev tswj cov cua sov, thiab tom qab-weld heat treatment (PWHT) yuav tsum tau tiv thaiv kom tsis txhob muaj kev kub ntxhov thiab tswj lub neej kev pab cuam?
A:Vuam cov qib siab no -kub austenitic yuav tsum muaj kev tswj xyuas kom tsis txhob cuam tshuam lawv cov yam ntxwv ntawm kev ua haujlwm -oxidation tsis kam rau 1.4833 thiab creep zog rau 1.4948.
Rau 1.4948 (304H), qhov tseem ceeb welding kev txhawj xeeb yogkev xav. Nrog cov ntsiab lus carbon txog 0.10%, lub tshav kub- cuam tshuam cheeb tsam (HAZ) yog qhov cuam tshuam rau chromium carbide nag lossis daus thaum raug kub ntawm 450℃thiab 850℃thaum vuam. Qhov no ua rau cov khoom muaj kev cuam tshuam rau intergranular corrosion nyob rau hauv kev pabcuam, tshwj xeeb tshaj yog tias cov kav dej tau ntsib cov corrosive condensates thaum kaw. Txhawm rau txo qhov no, muab tub lim hlau 1.4948 (304H sib piv) lossis, feem ntau, qis- carbon 1.4430 (308L) yog siv los tswj kev tiv thaiv corrosion.Tom qab-weld heat treatment (PWHT)-tshwj xeeb yog cov tshuaj annealing ntawm 1040-1100℃tom qab txias txias- yog txoj hauv kev zoo los kho corrosion kuj. Txawm li cas los xij, hauv kev tsim cov khoom siv hluav taws xob uas qhov kev kho cua sov tsis zoo, kev tswj xyuas hluav taws xob nruj heev (qhov siab tshaj qhov sib cuam tshuam ntawm 150-200 degree) thiab kev siv qis -carbon fillers yog qhov tseem ceeb kom txo qis kev nkag siab.
Rau 1.4833 (309S), vuam kev txiav txim siab tsom rau kev tswj xyuasoxidation tsis kamthiab tiv thaivkub tawg. Cov ntsiab lus chromium siab (22–24%) thiab cov ntsiab lus npib tsib xee (12–15%) ua rau cov hlau no tiv taus ntau dua 1.4948, txawm tias muaj cov pa roj carbon zoo sib xws. Txawm li cas los xij, nws cov thermal conductivity qis dua thiab ntau dua coefficient ntawm thermal expansion induce tseem ceeb residual stresses. Filler hlau xaiv feem ntau suav nrog 1.4847 (309Mo) lossis 1.4833 txuam chemistry kom ntseeg tau tias cov khoom siv vuam muaj qhov sib npaug oxidation tsis kam rau lub hauv paus hlau. Kev siv qis dua - alloy fillers (xws li 308L) yuav tsim qhov "tsis muaj zog txuas" uas ntsuas qhov zoo tshaj plaws hauv kev kub siab - kev pabcuam.PWHT feem ntau tsis tas yuav tsum muajrau 1,4833;. Hloov chaw, cov tshuaj annealing kho yuav raug siv tom qab fabrication yog tias cov khoom tau ua haujlwm txias heev lossis yog tias sigma theem embrittlement yog ib qho kev txhawj xeeb. Rau ob qho tib si alloys, autogenous welding (tsis muaj muab tub lim) feem ntau zam kom tsis txhob hnov qab (hauv 1.4948) thiab xyuas kom muaj kev tiv thaiv oxidation txaus hauv thaj tsam weld (hauv 1.4833).
4. Q: Nyob rau hauv petrochemical thiab refining ib puag ncig uas polythionic acid kev nyuaj siab corrosion cracking (PTA SCC) yog ib qho kev txhawj xeeb thaum lub sij hawm kaw, yuav ua li cas 1.4833 thiab 1.4948 coj tus cwj pwm, thiab dab tsi mitigation tswv yim feem ntau teev rau piping systems fabricated los ntawm cov alloys?
A:Polythionic acid kev nyuaj siab corrosion cracking yog ib qho tseem ceeb tsis ua hauj lwm mechanism rau austenitic stainless hlau nyob rau hauv refining thiab petrochemical kev pab cuam, tshwj xeeb tshaj yog nyob rau hauv cov units uas ua sulfur - bearing feedstocks xws li hydrotreaters, catalytic reformers, thiab cokers.
1.4948 (304H)PTA SCC muaj kev cuam tshuam ntau heev. Thaum lub sij hawm ua haujlwm siab - kub (txog 400 degree), chromium carbides precipitate ntawm grain ciam teb -ib qho tshwm sim uas yog qhov xav tau rau lub zog nkag. Txawm li cas los xij, qhov no sensitized microstructure tsim chromium-depleted aav nyob ib sab ntawm cov ciam teb. Thaum lub tsev raug kaw thiab raug rau huab cua thiab noo noo, sulfur compounds los ntawm cov txheej txheem kwj dej ua ke nrog oxygen thiab dej los tsim polythionic acids (H₂SₓO₆). Cov kua qaub no nyiam tawm tsam cov chromium-depleted grain ciam teb, ua rau intergranular cracking nyob rau hauv residual tensile stresses. Rau 1.4948 piping, qhov no yog qhov kev txhawj xeeb tseem ceeb ntawm kev ncaj ncees.
1.4833 (309S), nrog nws cov ntsiab lus chromium siab dua thiab feem ntau qis dua cov ntsiab lus carbon (tshwj xeeb tshaj yog nyob rau hauv 309S variant), nthuav tawm qhov kev tiv thaiv ntau dua rau kev nkag siab thiab yog li rau PTA SCC. Cov ntsiab lus chromium siab dua ua kom ntseeg tau tias txawm tias qee qhov carbide nag lossis daus tshwm sim, cov ciam teb khaws cia cov chromium txaus los tiv thaiv polythionic acid nres.
Cov tswv yim txo qis rau cov kav dej sib txawv raws li. Rau1.4948, cov qauv kev lag luam (xws li NACE SP0170) feem ntau ua haujlwmSoda tshauv (sodium carbonate) neutralizationThaum lub sij hawm kaw kom neutralize tej acidic condensates. Tsis tas li ntawd, ntau qhov kev qhia tshwj xeeb xav tau astabilizing kev kho cua sovlos yog kev siv cov qhab nia ruaj khov (xws li 321H lossis 347H) nyob rau hauv qhov chaw ntawm 304H rau cov ntawv thov kev pabcuam qaub tseem ceeb. Rau1.4833, thaum nws muaj qhov tsis kam lees, kev ua siab zoo tseem suav nrog cov txheej txheem vuam kev ntxhov siab thiab, hauv kev pabcuam hnyav, tom qab-weld solution annealing kom paub meej tias tsis yog-sensitized microstructure. Ob qho khoom siv yuav tsum tau ua tib zoo tswj xyuas cov kev ntxhov siab ntawm qhov seem los ntawm kev sib txuas kom zoo thiab, qhov twg ua tau, kev siv cov kev kho kev ntxhov siab xws li kev txhaj tshuaj peening.
5. Q: Los ntawm kev xa khoom thiab kev lees paub zoo, qhov tseem ceeb ntawm ASTM specifications, kev xeem yuav tsum tau ua, thiab cov ntaub ntawv dab tsi (EN 10204) uas sib txawv seamless kav hauv 1.4833 (309S) thiab 1.4948 (304H) rau siab - kub siab kev pab cuam?
A:Kev yuav cov kav hlau tsis muaj seamless nyob rau hauv cov qib siab no - qhov kub thiab txias xav tau kev ua raws li cov qauv ASTM tshwj xeeb thiab cov kev ntsuas ntxiv uas cuam tshuam txog qhov tseem ceeb ntawm lawv qhov chaw pabcuam.
Rau 1.4948 (304H), ASTM specification yog siv tauASTM A312 / A312M / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / A312M / ASTM A312 / ASTM A312 / A312M / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / A312M / ASTM A312 / ASTM A312 / A312M / ASTM A312 / A312M / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312 / ASTM A312) thiab ASTM A312M(Standard Specification rau Seamless, Welded, thiab hnyav hnyav ua hauj lwm Austenitic Stainless hlau kav). Txawm li cas los xij, rau siab - daim ntawv thov kub xws li boiler superheaters lossis refinery heaters, qhov nruj duaASTM A213 / A213M / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / A213M / ASTM A213 / A213M / ASTM A213 / ASTM A213 / A213M / ASTM A213 / ASTM A213 / A213M / ASTM A213 / ASTM A213 / ASTM A213 / A213M / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / A213M / ASTM A213 / ASTM A213 / A213M / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / ASTM A213 / A213M) တို့(Seamless Ferritic thiab Austenitic Alloy-Steel Boiler, Superheater, thiab Tshav Kub-Txiv Tubes) feem ntau hu ua. Cov kev cai tseem ceeb muaj xws li:
Tswj cov ntsiab lus carbon:0.04-0.10% nrog kev txwv nruj ntawm cov khoom seem.
Grain loj:Feem ntau teev raws li ASTM Tsis yog . 7 lossis coarser kom ntseeg tau tias muaj zog nkag.
Kev kuaj Hydrostatic:100% ntawm cov kav dej yuav tsum xeem dhau hydrostatic siab ntsuas ib qho kev qhia tshwj xeeb.
Nondestructive Examination (NDE):Kev kuaj ultrasonic (UT) lossis eddy kev kuaj tam sim no feem ntau raug yuam kom ntes laminations, suav nrog, lossis phab ntsa thickness variations.
Kev kuaj Hardness:Qhov siab tshaj plaws hardness txwv (feem ntau Tsawg dua los yog sib npaug rau 92 HRB) kom paub meej ductility thiab fabricability.
Rau 1.4833 (309S), thawj specification kuj yogASTM A 312 Cov Lus Qhiarau kev pabcuam piping, nrogASTM A 213muaj feem xyuam rau lub tshav kub exchanger thiab boiler tubing. Cov kev xav tau ntxiv feem ntau muaj xws li:
Positive Material Identification (PMI):100% PMI ntawm tag nrho cov yeeb nkab ntev yog qhov yuav tsum tau kuaj xyuas cov chromium elevated (22-24%) thiab npib tsib xee (12-15%) cov ntsiab lus, tiv thaiv cov nqi sib xyaws -ups nrog qis dua - cov qib alloy uas yuav ua tsis tau nyob rau hauv siab - kub kev pab cuam.
Kev kuaj Corrosion:Rau oxidizing kev pab cuam, intergranular corrosion testing ib ASTM A262 (Kev Xyaum E) yuav raug teev kom paub meej tias tsis kam mus rau sensitization.
Nto tiav:Rau siab -kub oxidation- cov ntawv thov tseem ceeb, cov khoom deg thiab passivated tau teev tseg kom tshem tawm cov nplai thiab xyuas kom muaj cov txheej txheem chromium oxide.
Rau ob qib,cov ntaub ntawvhauv qabTS EN 10204feem ntau yuav tsum tauHom 3.1(kev tshuaj xyuas daim ntawv pov thawj los ntawm cov chaw tsim khoom) rau cov qauv siab -cov ntawv thov kub, thiabHom 3.2(kev ywj pheej thib peb-kev soj ntsuam tog) rau cov ntawv thov tseem ceeb xws li kev tswj xyuas cov cuab yeej siv siab (PED) kev ua raws li kev ua raws li cov roj thiab roj tawm ntawm ntug dej hiav txwv. Tag nrho cov traceability los ntawm cov yaj mus rau qhov kawg khoom-xws li thaum tshav kub kub nrhiav, tshuaj ntsuam xyuas cov ntaub ntawv pov thawj, mechanical test results (tensile, flattening, flange tests), and NDE reports-yog standard for procurement in these high-value, critical-service material categories. Lub neej voj voog tus nqi tsim nyog rau cov qib no hinges ntawm lawv cov ntaub ntawv muaj peev xwm los tswj kev ua haujlwm zoo nyob rau hauv qhov ntsuas kub siab, feem ntau tshaj 100,000 teev ntawm kev pab cuam lub neej thaum tsim nyog, tsim, thiab khaws cia.
