2024 Tus sau: Howard Calhoun | [email protected]. Kawg hloov kho: 2023-12-17 10:28
Hlau yog cov khoom siv hlau ntau tshaj plaws hauv kev lag luam, raws li cov qauv thiab cov cuab yeej uas xav tau los ua. Nyob ntawm lub hom phiaj ntawm cov khoom siv no, ntau yam ntawm nws lub cev muaj zog, nrog rau qhov ceev, hloov. Hauv kab lus no, peb yuav txiav txim siab seb cov hlau twg muaj qhov ntom ntom hauv kg / m3.
steel yog dab tsi, thiab nws zoo li cas?
Ua ntej muab cov ntxhuav ntawm qhov ntom ntawm cov hlau hauv kg / m3, cia peb paub txog cov khoom nws tus kheej. Hlau nyob rau hauv metallurgy yog ib tug alloy ntawm hlau nrog carbon, cov ntsiab lus ntawm uas tsis pub tshaj 2.1 atomic feem pua. Yog tias muaj cov pa roj carbon ntau, ces graphite pib tsim hauv lub cev, uas ua rau muaj kev hloov pauv ntawm cov khoom ntawm cov hlau. Hauv particular, nws hardness thiab brittleness nce, thiab plasticity txo. Yog tias muaj ntau tshaj 2.1% carbon, ces cov hlau yog hu ua cam khwb cia hlau.
Qhov tseem ceeb tshaj plaws kom nkag siab yog cov hlau yog cov hlau alloy nrog lwm cov khoom uas ua raws li impurities. Yog tias hlau dhau los ua cov khoom tsis yog cov tub ntxhais,ces cov hlau no tsis yog hlau.
Steel txawv heev. Yog li, cov ntsiab lus ntawm cov pa roj carbon tsawg ua rau tsim cov chav kawm ntawm cov khoom siv. Nws cov ntsiab lus siab dua ua ib chav kawm ntawm cov cuab yeej steels. Ntxiv nrog rau carbon, muaj cov ntaub ntawv alloyed nrog ntau yam ntsiab lus. Piv txwv li, ntxiv ntau dua 13% chromium ua rau tsim cov khoom tsis muaj stainless, thiab cov ntsiab lus loj ntawm molybdenum thiab tungsten ua ib chav kawm ntawm cov hlau txiav.
Dab tsi txiav txim siab qhov ntom ntawm cov hlau?
Muaj ntau yam uas txiav txim siab qhov ntom ntawm cov hlau hauv kg / m3. Cov no suav nrog cov hauv qab no:
- ntom ntawm hlau nws tus kheej rau ib qho siv lead ua lattice;
- ntau thiab hom impurities;
- muaj cov theem.
Ntawm cov xwm txheej no, thawj qhov tseem ceeb tshaj plaws, vim nws yog hlau uas yog lub hauv paus ntawm cov alloys hauv kev xav. Raws li paub, nws muaj peev xwm muaj nyob rau hauv ob lub lattices: bcc (lub cev-centered cubic) thiab fcc (lub ntsej muag-centered cubic).
thawj hom lattice tsim cov ntawv hu ua ferritic steels, thib ob - austenitic. Lub fcc lattice yog kaw-packed, thaum lub bcc lattice yog looser packing ntawm atoms. Txawm li cas los xij, qhov ceev ntawm ferritic steels feem ntau siab dua li ntawm austenitic sawv daws yuav. Yog vim li cas rau qhov no yog qhov yooj yim, qhov tseeb yog tias fcc yog cov qauv ruaj khov tsuas yog nyob rau hauv qhov kub siab rau cov hlau ntshiab, thiab tag nrho cov hlau nthuav dav heev thaum rhuab. Qhov kawg ua rau kev poob qis.
Carbon steels
Dab tsi yog qhov ntom ntawm carbon steel? Feem ntau, peb tuaj yeem hais tias nws qis dua me ntsis ntawm qhov ntom ntawm BCC hlau ntshiab (7874 kg / m 3). Qhov kev txo qis me ntsis no yog vim qhov tseeb tias cov pa roj carbon hauv bcc lattice occupies octahedral pores. Qhov ceev ntawm carbon nws tus kheej nyob rau hauv cov qauv ntawm pob zeb diamond thiab graphite yog tsawg heev, yog li nws ntxiv rau hlau txo nws qhov nruab nrab ntom. Txij li thaum cov pa roj carbon atoms nyob hauv qhov loj octahedral pores, lawv me ntsis nce qhov nruab nrab lattice parameter, uas cuam tshuam me ntsis hauv qhov ntsuas qhov ntsuas. Hauv qab no yog ib lub rooj ntawm steel ntom hauv kg / m3, nyob ntawm qib thiab kub.
Alloy steels
Raws li tau hais, cov no suav nrog cov hlau-raws li alloys uas, ntxiv rau carbon, muaj lwm yam khoom xws li chromium, npib tsib xee, tungsten, vanadium, thiab lwm yam. Yog li, qhov ntom ntawm stainless hlau 12X18H9, muaj, ntxiv rau chromium, npib tsib xee, ntawm chav tsev kub yog 7900 kg / m 3, uas siab dua li cov hlau ntshiab BCC. Yog tias tsis muaj npib tsib xee hauv "stainless steel", ces nws qhov ceev yuav qis dua li cov hlau ntshiab, vim tias chromium atom yog sib dua li hlau.
Qhov ntom yog cov hlau nrawm. Lawv muaj ntau cov hlau hnyav xws li molybdenum thiab tungsten. Lawv qhov ceev tuaj yeem ncav cuag 8800 kg/m3.
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