409 vs 439 Ferritic Stainless Steels: Automotive Exhaust System Specialists

 

Dab tsi yog lawv cov ntsiab lus tseem ceeb thiab kev ua haujlwm tseem ceeb rau kev siv pa?

409 (UNS S40900) yog qib chromium lean nrog 10.5-11.75% Cr, 0.5% max Ni, thiab titanium stabilization, tsim los rau cov nqi-rhiab rau automotive exhaust manifolds thiab tailpipes. Nws muaj cov cua kub zoo txog li 650℃thiab yog cov khoom siv stainless hlau feem ntau siv rau cov qauv tsheb thauj neeg caij tsheb.439 (UNS S43900) muaj ntau dua chromium (17-19%) thiab titanium, nrog rau me me ntxiv ntawm niobium rau kev txhim kho kom ruaj khov. Nws tuaj yeem tiv taus qhov kub thiab txias txog li 800℃thiab muaj kev tiv thaiv zoo tshaj rau cov pa roj carbon monoxide, ua rau nws tsim nyog rau kev ua haujlwm thiab lub tshuab hluav taws xob diesel tsheb.

Yuav ua li cas lawv corrosion resistances ua nyob rau hauv automotive tso ib puag ncig?

409 tiv taus cov pa hluav taws xob dav dav hauv cov qauv roj av, tab sis tej zaum yuav muaj pitting corrosion nyob rau hauv cov tsheb diesel vim muaj cov ntsiab lus sulfur ntau dua hauv cov pa pa thiab ua haujlwm ntev dua.439 cov ntsiab lus chromium siab dua thiab kev ruaj ntseg dual (titanium + niobium) tiv thaiv cov pa roj condensate corrosion, uas yog ib qho teeb meem tshwm sim nyob rau hauv nres - cav pib cov kua qaub thiab diesel cav. noo noo thaum lub caij txias pib.Nyob rau hauv cov cheeb tsam ntug dej hiav txwv uas cov tshuaj tsuag ntsev tuaj yeem nkag mus rau hauv cov pa tawm, 439's corrosion resistance extends component lifespan by 2-3 times piv rau 409, justifying nws tus nqi siab dua rau off- txoj kev thiab marine-siv tsheb.

Hauv daim ntawv thov tsheb twg yog txhua qib qhov kev xaiv zoo tshaj?

409 yog qib qub rau cov qauv roj av cov neeg caij tsheb tso tawm manifolds, catalytic converter vaj tse, thiab tailpipes, qhov twg tus nqi yog tus thawj tsav tsheb thiab kev pab lub neej kev cia siab yog nruab nrab (5-8 xyoo).Nws kuj yog siv rau cov khoom siv hluav taws xob tom qab rau cov tsheb siv nyiaj, qhov kev them nqi yog qhov tseem ceeb tshaj qhov ntev {{5}4}39{100% kev siv sijhawm ntev}. roj av thiab diesel tsheb, suav nrog cov tsheb thauj khoom, SUVs, thiab cov tsheb sib tw, qhov twg cov pa cua txias dua thiab kev pabcuam lub neej yuav tsum nruj dua (10+ xyoo). Nws kuj tseem yog qib kev xaiv rau cov tshuab tso pa hauv thaj chaw ntug dej hiav txwv thiab sab qaum teb nrog hnyav ntsev siv rau de-icing.

Tus nqi thiab kev tsim khoom lag luam yog dab tsi- tawm ntawm ob qib?

409 yog qhov pheej yig dua (20-30%) dua li 439, ua rau nws tus nqi ntau tshaj - qib stainless hlau zoo rau siab - ntim automotive tso zis ntau lawm. Nws cov lean alloy muaj pes tsawg leeg kuj txo cov khoom hnyav, ua rau cov roj efficiency zoo dua.439 muaj qhov zoo dua weldability dua li 409, vim nws cov chromium siab dua thiab dual stabilization tiv thaiv rhiab heev thaum vuam, tshem tawm qhov xav tau tom qab-weld heat treatment. Qhov no ua rau nws yooj yim dua rau kev tsim cov khoom siv hluav taws xob zoo li lub taub hau thiab cov khoom sib koom ua ke.409 yuav tsum tau preheating thaum lub sij hawm vuam kom tsis txhob tawg, tshwj xeeb tshaj yog rau cov tuab-walled Cheebtsam xws li tso manifolds, thaum 439 tuaj yeem welded nrog cov qauv ferritic muab tub lim hlau yam tsis muaj preheating.

Dab tsi yog qhov tseem ceeb ntawm kev tsim thiab kev saib xyuas cov lus qhia rau kev siv pa?

Thaum vuam 409, siv tsawg- cov txheej txheem cua sov xws li TIG vuam kom txo cov qoob loo loj hlob hauv tshav kub- cuam tshuam thaj chaw, uas tuaj yeem txo cov tawv nqaij thiab ua rau muaj kev pheej hmoo ntawm thermal qaug zog tawg.Rau 439, siv cov hlau sib txuam ferritic muab tub lim (xws li, ER439) kom tsis txhob muaj kev sib txhuam thiab kev sib koom ua ke uas siv cov cua sov ua kom sov. tuaj yeem ua rau thermal expansion mismatch.Txhawm rau kev ua kom lub neej ntev, ob qib yuav tsum tau coated nrog siab -kub ceramic txheej, uas tiv thaiv sab nraud ntsev tsuag corrosion thiab sab hauv roj corrosion, tshwj xeeb tshaj yog nyob rau hauv ib puag ncig hnyav.