1. Q: Dab tsi yog qhov sib txawv ntawm cov hlau metallurgical ntawm 1.4845 (AISI 310) thiab 1.4571 (AISI 316Ti), thiab qhov sib txawv no txhais li cas rau lawv qhov kev ua haujlwm siab tshaj plaws thiab kev tiv thaiv corrosion profile?
A:Qhov tseem ceeb sib txawv ntawm 1.4845 thiab 1.4571 nyob rau hauv lawv cov tswv yim alloying, uas yog optimized rau tag nrho cov kev pab cuam ib puag ncig.
1.4845 (X15CrNiSi25-20), feem ntau hu ua AISI 310, yog siab -kub austenitic stainless hlau. Nws cov yam ntxwv txhais yog cov ntsiab lus chromium siab ntawm 24-26% thiab cov ntsiab lus nickel ntawm 19-22%. Qhov kev sib xyaw no muab tshwj xeeb oxidation tsis kam. Qhov siab chromium tso cai rau tsim kom muaj kev ruaj khov, ua raws chromium oxide (Cr₂O₃) nplai uas tiv thaiv kev sib kis txawm tias kub txog li 1100℃(2012℃F) hauv kev pabcuam cuam tshuam. Nws tsis muaj molybdenum; Hloov chaw, nws tso siab rau siab nickel kom muaj kev ruaj ntseg austenitic thiab tiv thaiv sigma theem embrittlement ntawm qhov kub siab.
1.4571 (X6CrNiMoTi17-12-2), los yog AISI 316Ti, yog molybdenum -alloyed austenitic stainless hlau tsim los rau ntub corrosion tsis kam ntau dua kub. Nws muaj 16.5-18.5% chromium, 10.5-13.5% nickel, thiab 2.0-2.5% molybdenum. Qhov sib ntxiv ntawm molybdenum muab kev tiv thaiv zoo tshaj rau pitting thiab crevice corrosion hauv chloride{10}}muaj ib puag ncig (xws li dej hiav txwv, cov kuab tshuaj lom). Tsis tas li ntawd, 1.4571 yog titanium-stabilized (Ti ~ 5 × C%). Qhov kev ruaj khov no tiv thaiv kev cuam tshuam ntawm intergranular corrosion (sensitization) tom qab vuam los ntawm kev khi cov pa roj carbon monoxide rau hauv titanium carbides es tsis txhob cia chromium carbides tsim ntawm cov ciam teb. Yog li ntawd, 1.4845 yog cov khoom ntawm kev xaiv rau radiant tubes, furnace muffles, thiab thermal ua cov khoom, thaum 1.4571 yog tus qauv rau kws, zaub mov ua, thiab marine piping systems uas corrosion kuj ntawm nruab nrab kub (feem ntau hauv qab 400 degree) yog qhov tseem ceeb.
2. Q: Nyob rau hauv cov ntsiab lus ntawm siab -kub piping systems xws li reformers los yog incinerators, dab tsi tshwj xeeb tsim kev txiav txim siab (creep, oxidation, thiab thermal qaug zog) yuav tsum tau suav rau thaum qhia txog 1.4845 kav piv rau 1.4571 kav?
A:Thaum tsim cov kav dej rau kev ua haujlwm siab - qhov kub thiab txias, kev xaiv ntawm 1.4845 thiab 1.4571 yog tswj hwm los ntawm cov khoom muaj peev xwm tiv taus kev ntxhov siab thiab kev tawm tsam ib puag ncig ib txhij.
Rau1.4845 (310), tus tsim tsom raucreep zog thiab oxidation kuj. Raws li ASME Tshooj II, Ntu D, 1.4845 tau tso cai rau kev ntxhov siab qhov tseem ceeb uas txuas mus txog kwv yees li 815℃(1500℃F) rau kev pabcuam ruaj khov. Cov kws kho tsheb yuav tsum suav txog kev nkag mus rau - lub sijhawm - nyob ntawm cov yas deformation uas tshwm sim nyob rau hauv qhov kev thauj khoom tas li ntawm qhov kub thiab txias . 1.4845 tuav nws cov qauv austenitic yam tsis muaj theem hloov pauv, tab sis nws muaj feem cuam tshuam rau qib sigma yog tias tuav ntawm 600℃thiab 900℃rau lub sijhawm ntev. Txawm li cas los xij, nws cov ntsiab lus nickel siab txo qhov kev pheej hmoo no zoo dua li qis dua - qib alloyed. Thermal qaug zog kuj yog ib qho tseem ceeb; 1.4845 muaj cov coefficient siab heev ntawm thermal expansion (CTE), yuav tsum tau ua tib zoo tsim cov voj voog loj los yog lub hauv siab kom tiv thaiv buckling lossis weld qaug zog hauv kev pabcuam cyclic.
Rau1.4571 (316 Ti), siab -kub siv feem ntau txwv. Thaum nws tuaj yeem siv tsis tu ncua mus txog 750 degree, nws cov creep kuj degrades ho siab tshaj 550 degree. Lub titanium stabilization muab kev tiv thaiv zoo rau polythionic acid kev nyuaj siab corrosion cracking (SCC) thaum lub sij hawm kaw, uas yog zoo rau refineries, tab sis nws tsis impart tib theem ntawm oxidation scaling tsis kam raws li 1.4845. Nyob rau hauv siab -kub oxidizing atmospheres, 1.4571 yuav tsim ib txheej oxide tsis tshua muaj zog thiab muaj kev ua kom nrawm hlau poob los ntawm kev ntsuas. Yog li, yog tias lub kav dej tuav cov pa taws ntawm 950 degree, 1.4845 yog qhov yuav tsum tau ua; Yog tias lub kaw lus tuav cov kua dej kub ntawm 300℃nrog cov tshuaj chloride, 1.4571 yog qhov kev xaiv zoo tshaj kom tsis txhob pitting, txawm tias qhov kub thiab txias yuav qis dua.
3. Q: Dab tsi yog qhov tseem ceeb ntawm kev tsim cov khoom sib tw uas cuam tshuam nrog vuam 1.4571 (316Ti) kav piv rau 1.4845 (310) cov kav dej, thiab dab tsi tom qab-weld heat treatment (PWHT) raws tu qauv-yog tias muaj- raug pom zoo rau txhua tus los tiv thaiv corrosion?
A:Lub vuam metallurgy ntawm ob qib no yuav tsum muaj cov txheej txheem sib txawv los khaws lawv cov corrosion tshwj xeeb -cov khoom tiv taus.
1.4571 (316 Ti)nthuav tawm cov teeb meem ntsig txog titanium stabilization. Thaum titanium ntxiv los tiv thaiv kev hnov mob, nws kuj cuam tshuam rau lub pas dej da dej. Titanium muaj affinity siab rau oxygen thiab nitrogen; Yog tias kev tiv thaiv kev tiv thaiv roj tsis txaus, titanium oxides tuaj yeem tsim, ua rau "tsib kab txaij" lossis kev sib kis kab mob. Ntau qhov tseem ceeb, 1.4571 feem ntau yog welded siv cov hlau muab tub lim 1.4576 (316L nrog Mo siab dua) lossis 1.4570 (316Ti). Ib qho yuam kev feem ntau yog siv 316L muab tub lim, uas, thaum corrosion{10}}resistant, tej zaum yuav tsis phim cov titanium{11}}stabilized puag hlau zoo kawg nkaus.Tom qab-weld heat treatment (PWHT)feem ntau yogtsis xav tauua 1,4571. Qhov tseeb, PWHT nyob rau hauv qhov rhiab heev (450-850 degree) yog kev puas tsuaj tshwj tsis yog tias cov khoom siv yav tas los daws tau -annealed. Lub titanium stabilization ua kom lub Heat Afected Zone (HAZ) tseem resistant rau intergranular corrosion nyob rau hauv raws li -welded mob.
1.4845 (310), vim nws cov ntsiab lus siab chromium thiab npib tsib xee, muaj cov thermal conductivity qis dua thiab ntau dua coefficient ntawm thermal expansion dua li carbon steel. Qhov no ua rau muaj kev ntxhov siab ntau dua thiab muaj kev pheej hmoo ntau dua ntawm kub tawg yog tias qhov sib koom ua ke tau nruj dhau lawm. Vuam feem ntau ua tau siv 1.4847 (310Mo) lossis 1.4848 muab cov hlau ua kom muaj zog siab - kub.PWHT tsis tshua muaj uantawm 1.4845 rau kev tsim qauv; Hloov chaw, cov tshuaj annealing kev kho mob (hnyav txias los ntawm ~ 1080 degree) yog siv yog tias cov khoom tau raug rhiab heev los yog muaj kev txhawj xeeb txog sigma theem embrittlement tom qab fabrication. Txawm li cas los xij, nyob rau hauv feem ntau cov xwm txheej fabrication, 1.4845 yog siv nyob rau hauv cov kev daws teeb meem -annealed mob nrog nruj tswj ntawm tshav kub inputs (tswj interpass kub hauv qab no 150 degree) kom tsis txhob carbide nag lossis daus thiab txo cov residual stresses uas yuav ua rau kom nkag mus tsis ua hauj lwm nyob rau hauv kev pab cuam.
4. Q: Hauv cov chaw ua tshuaj lom neeg uas muaj cov ntxhia pob zeb muaj zog (piv txwv li, phosphoric lossis sulfuric acid) ntawm qhov kub nruab nrab, qhov muaj molybdenum hauv 1.4571 cuam tshuam li cas rau nws cov corrosion kuj piv rau 1.4845, uas tsis muaj molybdenum?
A:Lub xub ntiag ntawm molybdenum (2.0–2.5%) hauv 1.4571 yog qhov txiav txim siab rau kev ua haujlwm hauv kev txo cov kua qaub ib puag ncig thiab chloride-cov kabmob xov xwm, whereas 1.4845 tso siab rau nws cov chromium siab thiab npib tsib xee rau kev tiv thaiv hauv oxidizing acids.
1.4571 (316 Ti)excels nyob rau hauv ib puag ncig qhov twgtxo cov kua qaubthiabtshuaj chloride are concerns. Molybdenum significantly increases the material's Pitting Resistance Equivalent Number (PREN). In phosphoric acid production (wet process), where fluoride and chloride ions are present, 1.4571 is often the minimum specification to resist pitting and crevice corrosion. Similarly, in dilute sulfuric acid (up to 10% concentration at ambient temperatures), the molybdenum content provides a passive film stability that 1.4845 cannot match. However, 1.4571 is susceptible to stress corrosion cracking (SCC) in hot, concentrated chloride solutions (e.g., >60 degree).
1.4845 (310), tsis muaj molybdenum, tso siab rau nws cov chromium siab (25%) thiab npib tsib xee (20%) los tiv thaivoxidizing acidsxws li kub, concentrated nitric acid. Nyob rau hauv ib puag ncig sulfuric acid, thaum 1.4845 muaj kev tiv thaiv zoo rau oxidizing tej yam kev mob, nws raug kev txom nyem los ntawm ntau dua corrosion tus nqi tshaj 1.4571 nyob rau hauv stagnant los yog txo cov cheeb tsam uas cov kua qaub yuav depleted ntawm oxygen. Tsis tas li ntawd, 1.4845 tiv taus cov tshuaj chloride-induced SCC- ntau dua li 1.4571-vim nws cov ntsiab lus ntau dua nickel. Txawm li cas los xij, nws muaj kev cuam tshuam ntau dua rau pitting hauv dej hiav txwv stagnant lossis brine kev daws teeb meem vim nws tsis muaj molybdenum xav tau los tswj cov yeeb yaj kiab tsis zoo tiv thaiv halide nres. Yog li ntawd, rau lub raj xa dej nqa dilute sulfuric acid nrog chloride paug ntawm 80 degree, 1.4571 yuav raug xaiv; rau lub raj xa dej nqa kub, oxidizing nitric acid lossis kub kub combustion gases, 1.4845 yuav yog qhov kev xaiv zoo tshaj.
5. Q: Los ntawm tus nqi ntawm lub neej (LCC) thiab cov khoom siv tshwj xeeb, kev xav txog kev yuav khoom tseem ceeb yog dab tsi (piv txwv li, ASTM cov qauv, kev ua tiav, thiab kev sim) rau 1.4571 thiab 1.4845 cov kav dej hauv kev lag luam tshuaj thiab petrochemical, raws li txoj cai?
A:Cov kev yuav khoom thiab kev tsim nyog rau ob qib no sib txawv heev raws li qhov kawg -siv kev lag luam- tshuaj tiv thaiv petrochemicals - txiav txim qhov txawv cov qauv thiab kev tswj kom zoo.
Rau1.4571 (316 Ti), tshwj xeeb hauv covtshuaj thiab biotechnologyKev lag luam, kev yuav khoom feem ntau ua raws li ASTM A312 (seamless lossis welded) lossis A358 (welded), tab sis nrog cov kev xav tau nruj ntxiv. Qhov saum npoo tiav yog qhov tseem ceeb. Cov txheej txheem zeb tiav feem ntau tsis tsim nyog; es tsis txhob, mechanical polishing (xws li, 180-grit lossis 320-grit internal inch tiav) yog teev kom ua tiav qhov roughness (Ra) ntawm<0.5 µm to prevent bacterial adhesion and ensure cleanability. Electro-polishing is frequently mandated to enhance the chromium oxide layer and further reduce surface activity. Furthermore, cov ntsiab lus ferriteyog tswj nruj heev. Rau autogenous orbital welding (feem ntau nyob rau hauv pharma), lub vuam yuav tsum muaj tsawg tshaj li 1% ferrite kom muaj corrosion kuj thiab tiv thaiv pitting. Daim ntawv pov thawj yuav tsum muaj tag nrho traceability los ntawm cov yaj mus rau cov khoom kawg, suav nrog EN 10204 3.1 ntawv pov thawj nrog cov kev txwv tshwj xeeb ntawm cov ntsiab lus suav nrog.
Rau1.4845 (310), siv dav hauvpetrochemical, refinery, thiab thermal uadaim ntawv thov, kev yuav khoom raws li ASTM A312 (rau kev pabcuam dav dav) lossis ASTM A358 rau hluav taws xob -fusion-welded loj- cov kav dej. Kev tsom xam hloov ntawm qhov chaw zoo nkauj raumechanical kev ncaj ncees ntawm qhov kub thiab txias. Specifications feem ntau suav nrog agrain loj yuav tsum tau(feem ntau ASTM Tsis muaj. 5 lossis coarser) txhawm rau txhim kho creep tsis kam. Tsis yog -kev kuaj kev puas tsuaj (NDT) yog qhov nruj dua: 100% radiography (RT) ntawm tag nrho cov kab ntev thiab cov voj voog ncig yog tus qauv, thiab kev ntsuas cov kua dej nkag (PT) ntawm cov cua sov- yuav tsum muaj kev cuam tshuam rau thaj chaw uas tuaj yeem nthuav tawm hauv qab thermal cycling. Tsis tas li ntawd, rau 1.4845, cov khoom siv tshwj xeeb feem ntau ua haujlwmKev txheeb xyuas cov khoom zoo (PMI)ntawm txhua cov yeeb nkab ntev los txheeb xyuas cov ntsiab lus siab nickel thiab chromium, tiv thaiv kev sib xyaw ua ke - nce nrog qis - qib 304 lossis 316 stainless hlau, uas yuav ua tsis tau zoo nyob rau hauv qhov kub ntawm - qhov kub thiab txias qhov chaw. Tus nqi lifecycle ntawm 1.4845 yog tsim nyog los ntawm nws lub neej ntev nyob rau hauv huab cua sov (feem ntau 20+} xyoo), whereas 1.4571 tus nqi yog ncaj ncees los ntawm nws tsis kam mus rau kev sib kis thiab corrosion nyob rau hauv cov txheej txheem tu cev tseem ceeb.
