430 vs 439 Stainless hlau: Ferritic Corrosion-Resistant Alloys

 

Q1: Dab tsi yog cov tshuaj muaj pes tsawg leeg, cov khoom siv kho tshuab, thiab kev siv thawj zaug ntawm 430 thiab 439 stainless hlau?
A1: Qib 430 yog ib qho yooj yim ferritic stainless hlau nrog ib ncig ntawm 16-18% chromium thiab tsis muaj npib tsib xee, muab kev tiv thaiv corrosion zoo hauv cov cua me me. Qib 439 yog cov qauv ruaj khov, zoo ib yam hauv cov ntsiab lus chromium tab sis nrog qhov tseem ceeb ntxiv ntawm titanium (feem ntau 0.15% min). Titanium ua raws li kev ruaj ntseg los ntawm kev khi nrog carbon thiab nitrogen. Ob qib yog sib nqus, muaj zog nruab nrab, thiab zoo heev tiv thaiv kev ntxhov siab corrosion cracking . 430 yog dav siv rau cov khoom siv sab hauv trim, automotive décor, thiab fasteners . 439, nrog nws txhim khu kev ruaj ntseg, yog teev rau automotive cua tshuab (txias kawg), tshav kub exchangers, thiab lub tshuab ntxhua khaub ncaws tubs.

Q2: Yuav ua li cas ntxiv ntawm titanium hauv 439 stainless hlau txhim kho nws cov kev ua tau zoo tshaj 430?
A2: Titanium ua rau kev ua tau zoo los ntawm kev tiv thaiv "sensitization." Thaum vuam los yog siab - qhov kub thiab txias, cov pa roj carbon hauv cov hlau tuaj yeem ua ke nrog chromium los ua chromium carbides ntawm cov ciam teb nplej, depleting hauv zos corrosion kuj. Hauv 439, titanium muaj kev sib raug zoo rau cov pa roj carbon ntau dua li chromium. Nws tsim ruaj khov titanium carbides ua ntej, tawm hauv tag nrho cov chromium hauv kev daws kom muaj kev tiv thaiv oxide txheej. Qhov no "stabilization" pab 439 superior tiv thaiv intergranular nres tom qab vuam los yog cua sov, ib qho tsis muaj zog nyob rau hauv unstabilized qib zoo li 430.

Q3: Nyob rau hauv dab tsi hom corrosive ib puag ncig puas 439 outperform 430?
A3: Qib 439 ua tau zoo tshaj 430 nyob rau hauv ib puag ncig uas muaj cua sov, me me acids, thiab condensing noo noo. Nws cov qauv stabilized ua rau nws muaj zog heev rau intergranular corrosion nyob rau hauv welded seem, uas yog ib qho tseem ceeb rau lub tshuab pa. Nws kuj tseem qhia tau tias muaj kev tiv thaiv zoo dua rau oxidizing acids thiab pitting hauv chloride- muaj cov dej (xws li hauv cov tshuab rhaub dej) piv rau 430. Txawm tias tsis tsim nyog rau cov tshuaj lom neeg los yog cov dej hauv hiav txwv, 439 tuaj yeem ua rau muaj kev txhoj puab heev nyob rau hauv cov tsheb hauv qab lub cev, lub tank dej kub, thiab qee yam khoom noj khoom haus 30 tej zaum yuav ua tsis tau.

Q4: Puas muaj qhov tsis zoo lossis kev txiav txim siab tshwj xeeb thaum ua haujlwm nrog 439 piv rau 430?
A4: Thawj qhov kev txiav txim siab yog tus nqi, raws li 439 feem ntau nqa tus nqi tshaj 430 vim qhov sib ntxiv ntawm titanium. Fabricators yuav tsum tau nco ntsoov tias thaum 439 lub weldability yog deb tshaj li 430, tag nrho cov qib ferritic yuav tsum tau ceev faj welding xyaum (tsawg tshav kub input, tsim nyog shielding) kom tsis txhob muaj ntau yam qoob loo loj hlob thiab embrittlement nyob rau hauv lub tshav kub - cuam tshuam cheeb tsam. Los ntawm txoj kev xav, 439 tej zaum yuav tsis yooj yim rau txhua hom thiab ntau thiab tsawg raws li 430 ubiquitous. Txawm li cas los xij, rau daim ntawv thov raug, nws lub neej kev pab ntev dua thiab kev ntseeg siab feem ntau ua pov thawj rau thawj zaug peev thiab kev npaj.

Q5: Thaum twg ib qhov project tshwj xeeb yuav xaiv 439 ntau dua 430 stainless hlau?
A5: Xaiv 439 thaum koj qhov project cuam tshuam nrog kev sib txuas ntawm cov hauv qab no:vuam xav tau, raug rau qhov kub siab(txog ~ 800℃intermittently), los yogtiv tauj nrog cov xov xwm ua phem me mezoo li condensate los yog organic acids. Nws yog qhov kev xaiv ua haujlwm tsis zoo tshaj 430 rau cov tshuab hluav taws xob niaj hnub siv hluav taws xob (post-catalyst) thiab cov kav dej hauv tsev. Yog tias daim ntawv thov yog cov khoom siv zoo nkauj, sab hauv tsev, thiab tsis muaj vuam (xws li lub vaj huam sib luag zoo nkauj), ces 430 tseem yog ib qho khoom siv zoo kawg nkaus thiab tus nqi - cov khoom siv tau zoo. Txoj cai yog: yog welding koom nrog ib puag ncig kev pabcuam corrosive, hloov mus rau 439.