Kub ua haujlwm thiab kub ua haujlwm yog cov yam ntxwv tseem ceeb ntawm cov hlau

2024 Tus sau: Howard Calhoun | [email protected]. Kawg hloov kho: 2023-12-17 10:28

Kub ua haujlwm thiab kub ua haujlwm yog cov yam ntxwv tseem ceeb heev. Qee cov khoom siv tshuab engineering ua haujlwm nyob rau hauv cov xwm txheej nyuaj heev ntawm qhov kub siab. Raws li cov qauv hlau, thaum rhuab, hloov pauv lawv cov khoom siv thiab lub cev sai sai, pib nquag oxidize thiab daim ntawv teev, uas yog qhov tsis txaus ntseeg thiab tsim kev hem thawj ntawm kev ua tsis tiav ntawm tag nrho cov rooj sib txoos, thiab tej zaum yuav muaj xwm txheej loj. Txhawm rau ua haujlwm ntawm qhov kub siab, cov khoom siv engineers, nrog kev pab los ntawm metallurgists, tsim ib tug xov tooj ntawm tshwj xeeb steels thiab alloys. Kab lus no qhia me ntsis txog lawv.

Kub-resistant steels

Ntau tus neeg sib npaug lub tswv yim ntawm kev tiv thaiv tshav kub nrog lub tswv yim xws li kev tiv thaiv tshav kub. Tsis muaj qhov xwm txheej yuav tsum ua li no. Thaum tshav kub kub kuj tseem hu ua liab brittleness. Thiab lub tswv yim no txhais tau hais tias muaj peev xwm ntawm cov hlau (los yog alloy) khaws ciahigh mechanical zog thaum ua haujlwm ntawm qhov kub siab. Ntawd yog, xws li cov hlau, txawm tias thaum tshav kub kub rau lub teeb liab (nws yog qhov zoo rau qhov kub siab tshaj 550 ° C), yuav tsis nkag thiab khaws cov rigidity txaus.

Hauv cov ntsiab lus yooj yim, kev tiv thaiv tshav kub yog lub peev xwm ntawm cov khoom siv los tswj kev ua haujlwm thaum rhuab mus rau qhov kub thiab txias. Cov txheej txheem zoo tib yam steels, txawm tias muaj cua sov me ntsis, ua cov ductile, uas tsis suav nrog lawv txoj kev siv rau kev tsim cov khoom lag luam ntawm qhov kub thiab txias.

Cov qib sib txawv ntawm cov hlau thiab alloys muaj qhov sib txawv ntawm cov cua sov. Qhov ntsuas no nyob ntawm cov tshuaj muaj pes tsawg leeg ntawm cov khoom. Kev ntsuas kub ua haujlwm tuaj yeem ua tiav rau lub sijhawm ntev. Tab sis feem ntau, cov qauv rhuab hauv qhov cub rau qhov kub thiab txias tau sim tensile rau lub sijhawm luv luv.

Kub-resistant steels

Thaum tshav kub kub ua haujlwm, sib piv rau cov cua sov, yog lub peev xwm ntawm cov ntaub ntawv los tiv thaiv kev txhim kho corrosion txheej txheem thaum ua haujlwm kub. Cov hlau zoo tib yam, yog tias raug cua sov (nrog rau kev kho cua sov hauv qhov chaw tiv thaiv lossis hauv lub tshuab nqus tsev), pib oxidize. Tsis tas li ntawd, nrog rau lub sijhawm cua sov, cov pa roj carbon monoxide ntawm cov khoom pib hlawv tawm. Yog li ntawd, qhov saum npoo yog depleted ntawm carbon, uas ua rau ib tug ntse hloov nyob rau hauv lub mechanical zog (feem ntau hardness) nyob rau saum npoo. Hnav tsis kam poob. Tau txais kev txhim kho tsis zoophenomenon, zoo li ib tug thab plaub. Cov hlau no tuaj yeem ua haujlwm ntawm qhov kub ntawm 550 ° C.

txhawm rau txhawm rau ua kom cov cua sov ntawm cov hlau, nws cov yaj yog alloyed nrog silicon, aluminium thiab chromium. Qee zaum nws txaus los ua kom cov cua sov ua haujlwm ntawm qhov chaw ntawm qhov chaw. Hauv qhov no, siliconizing lossis aluminizing (saturation ntawm txheej txheej nrog silicon lossis aluminium atoms, feem) yog siv rau hauv cov hmoov nruab nrab.

cov khoom siv siab melting

Thaum ua haujlwm ntawm qhov kub tshwj xeeb, cov ntaub ntawv xav tau tsis tuaj yeem siv, txij li thaum kub hauv cheeb tsam ntawm 2000 ° C, melting pib tshwm sim (ib theem ua kua raug tso tawm). Rau cov hom phiaj no, cov hlau refractory yog siv: tungsten, niobium, vanadium, zirconium, thiab lwm yam. Cov ntaub ntawv no kim heev, tab sis cov engineers tseem tsis tau pom qhov tsim nyog rau lawv.

Tus yam ntxwv ntawm chromium thiab npib tsib xee raws alloys

Alloys nrog cov cua kub tsis kam yog qhov xav tau zoo hauv kev tsim hluav taws xob engineering (cov hniav ntawm chav turbines, qhov chaw ntawm lub tshuab dav hlau, thiab lwm yam). Ntxiv mus, qhov kev xav tau ntawm cov ntaub ntawv zoo li no tau loj hlob tas li. Tsis tas li ntawd, kev tsim khoom xav kom cov kws tshawb fawb kom tau txais cov khoom siv ntau thiab ntau dua uas tuaj yeem tswj tau lawv cov kev ua tau zoo ntawm qhov kub thiab txias heev. Yog li ntawd, kev ua haujlwm tas li ua rau kom cov cua sov ua haujlwm. Nickel, lossis theej alloying hlau nrog cov khoom no, pab txhawb rau qhov no.

Txhua cov cua sov resistant steelsyog alloyed nrog npib tsib xee (tsis pub tsawg tshaj 65%). Chrome yog qhov yuav tsum tau ua. Cov ntsiab lus ntawm cov khoom no yuav tsum tsis pub tsawg dua 14%. Txwv tsis pub, cov hlau saum npoo yuav ua rau oxidized.

Cov hlau yog ntxiv alloyed nrog txhuas, vanadium thiab lwm yam refractory ntsiab. Aluminium, piv txwv li, txawm nyob rau hauv chav tsev kub yog them nrog nyias oxide zaj duab xis, uas tiv thaiv corrosion los ntawm kev nkag mus tob rau hauv cov hlau. Ntawd yog, tsis muaj qhov ntsuas tau tsim.