440A vs 440B Martensitic Stainless Steels: Balanced Corrosion vs Mid-Hardness Wear Resistance

 

Dab tsi yog lawv cov ntsiab lus tseem ceeb thiab cov cuab yeej cuab tam sib txawv?

440A muaj 0.60–0.75% C, 16–18% Cr, Tsawg dua lossis sib npaug li 0.75% Mo, tsis muaj npib tsib xee. Tom qab kev kho cua sov (quenching + tempering), nws ua tiav qhov siab tshaj plaws hardness ntawm 56 HRC, ntsuas qhov hnav tsis kam nrog kev tiv thaiv corrosion rau qhov chaw qhuav.440B nta 0.75-0.95% C, 16-18% Cr, Tsawg dua lossis sib npaug li 0.75% Mo, tsis muaj nickel. Nws cov ntsiab lus carbon siab dua tsim cov chromium carbides ntau dua, ua rau lub siab tawv ntawm 58 HRC-2 HRC siab dua 440A-nrog me ntsis txo corrosion kuj.Ob qib yog sib nqus thiab xav tau kev kho cua sov kom qhib lawv lub peev xwm hardness tag nrho; lawv yog mos thiab ductile nyob rau hauv lub xeev annealed.

Lawv cov tawv tawv thiab hnav tsis kam txhais li cas kom xaus - siv daim ntawv thov?

440A yog haum rau qis-rau- nruab nrab hnav cov cuab yeej txiav thiab cov khoom siv kho tshuab: riam chav ua noj, vaj txiav, cov kabmob sib tw me me, thiab lub valve stems rau cov tshuab ziab khaub ncaws. Nws cov kev tiv thaiv corrosion ua rau nws siv tau rau cov ntawv thov sab hauv tsev nrog rau qee lub sij hawm me me ya raws.440B excels hauv nruab nrab- hnav daim ntaub ntawv: muaj txiab rau cov khoom uas tsis yog- abrasive cov ntaub ntawv, precision ntsuas cov cuab yeej, thiab phom phom qhov chaw. Nws cov hardness siab dua txhim kho ntug tuav piv rau 440A, txawm hais tias nws yog nkig ntau dua.Txawm tsis pom zoo rau qib siab - cuam tshuam qhov chaw- lawv cov qauv martensitic ua rau lawv yooj yim rau chipping nyob rau hauv hnyav loads.

Yuav ua li cas lawv corrosion resistances piv nyob rau hauv txawv ib puag ncig?

440A muaj kev tiv thaiv corrosion siab tshaj plaws ntawm 440- cov qib series, zam qhov ziab hauv tsev thiab luv- lub sij hawm raug rau ambient humidity yam tsis muaj xeb tseem ceeb. Kev siv roj tsis tu ncua tuaj yeem ua kom nws lub neej ua haujlwm nyob rau hauv ib nrab- teeb tsa sab nraum zoov.440B cov pa roj carbon ntau dua cuam tshuam cov chromium passive zaj duab xis ntau dua 440A, ua rau nws yooj yim rau xeb hauv qhov chaw ntub dej. Nws yuav tsum muaj cov txheej txheem tiv thaiv (piv txwv li, oiling, plating) rau kev siv sab nraum qhov chaw qhuav hauv tsev. Ob qib tsis tsim nyog rau kev siv dej hiav txwv, ntug dej hiav txwv, lossis tshuaj siv tshuaj lom neeg- qib nag lossis daus zoo li 17-4 PH yog lwm txoj hauv kev zoo dua rau cov xwm txheej no.

Dab tsi yog cov lus qhia txog kev kho cua sov tseem ceeb rau cov qib no?

Rau 440A: Austenitize ntawm 1010-1060 degree, quench nyob rau hauv cov roj rau hauv chav tsev kub, ces temper ntawm 150-200℃kom sib npaug hardness thiab toughness. Tsis txhob tempering siab tshaj 200 degree, vim qhov no yuav txo qis hardness.Rau 440B: Siv tib yam austenitizing kub ntau yam (1010–1060 degree), roj quench, ces temper ntawm 150–200℃. 440B tau txais txiaj ntsig los ntawm ob chav tempering kom tshem tawm qhov kub thiab txias tam sim ntawd. quenching los tiv thaiv tawg los ntawm residual kev nyuaj siab.

Cov kev txwv tseem ceeb thiab cov txheej txheem kev thov yog dab tsi?

440A thiab 440B muaj qhov tsis zoo weldability- vuam ua rau carbide nag lossis daus ntawm cov ciam teb, ua rau brittleness thiab tawg. Kev sib koom ua ke (xov xov, xovxwm-fitting) yog qhov nyiam rau kev sib dhos.440B tus nqi me ntsis ntau dua 440A vim yog cov ntsiab lus nruj dua, yog li nws yuav tsum tsuas yog siv thaum hnav hnyav dua yog qhov tseem ceeb.Xaiv 440A rau kev sib npaug corrosion thiab nruab nrab hardness; xaiv 440B rau kev txhim kho hnav tsis kam nyob rau hauv qhuav, qis- daim ntaub ntawv ntub dej.