Cementite, tseem hu ua hlau carbide (Fe₃C), yog ib qho tseem ceeb intermetallic compound pom nyob rau hauv microstructure ntawm hlau thiab cam khwb cia hlau. Tab sis dab tsi yog cementite, thiab vim li cas nws thiaj li tseem ceeb hauv kev siv metallurgical? Tsab ntawv blog no yuav tshawb txog cov yam ntxwv, tsim, thiab lub luag haujlwm ntawm cementite hauv ntau hom hlau.
Yuav ua li cas Cementite tsim nyob rau hauv Steel?
Cementite tsim los ntawm kev sib xyaw ntawm hlau thiab carbon ntawm qhov kub siab. Nyob rau hauv cov hlau - cov pa roj carbon theem daim duab, cementite yog sawv cev raws li ib tug compound uas muaj kwv yees li 6.67% carbon los ntawm qhov hnyav. Nws tsim feem ntau tshwm sim thaum lub sij hawm solidification ntawm molten hlau los yog thaum lub sij hawm kho cua sov txheej txheem ntawm hlau.
Nyob rau hauv cov ntsiab lus ntawm steel lub microstructure, cementite feem ntau coexists nrog ferrite ( - hlau) thiab pearlite, uas yog ib txheej txheej uas muaj alternating bands ntawm ferrite thiab cementite. Lub xub ntiag ntawm cementite ho cuam tshuam cov khoom siv ntawm cov hlau, vim nws ua raws li tus neeg sawv cev hardening.
Cov txheej txheem hloov pauv
Thaum lub sij hawm txias thiab solidification, carbon yuav nyob twj ywm yaj nyob rau hauv cov hlau lattice los yog ua ke nrog hlau los ua cementite. Ntau yam kev hloov pauv ua rau muaj kev tsim cov cementite:
Austenitization: Thaum cov hlau kub siab tshaj qhov kub tseem ceeb, nws hloov mus rau hauv austenite ( - hlau), lub ntsej muag - nruab nrab cubic qauv muaj peev xwm ntawm cov pa roj carbon ntau.
Txias thiab Theem Transformation: Thaum txias, nyob ntawm tus nqi ntawm cov cua txias thiab cov ntsiab lus carbon, austenite tuaj yeem hloov mus rau hauv microstructures sib txawv. Piv txwv li, kev txias qeeb yuav ua rau tsim pearlite, thaum txias ceev tuaj yeem ua rau martensite, nrog cementite precipitating thaum lub sij hawm hloov pauv.
Cementite nag lossis daus: Thaum lub sij hawm tempering txheej txheem ntawm martensitic steel, cementite tuaj yeem precipitate tawm ntawm supersaturated martensitic matrix, pab txhawb rau tag nrho cov khoom ntawm cov khoom.
Dab tsi yog cov yam ntxwv tseem ceeb ntawm Cementite?
Cementite muaj ntau yam tseem ceeb uas cuam tshuam rau cov khoom ntawm cov hlau:
Siab Hardness: Cementite yog qhov nyuaj tshaj li ferrite, pab txhawb rau tag nrho hardness ntawm hlau. Nws qhov hardness yog ib qho ntawm cov laj thawj vim li cas nws thiaj li tsim nyog hauv qee qhov kev siv siab - zog.
Brittleness: Thaum cementite txhim kho hardness, nws kuj qhia txog brittleness. Cov yam ntxwv no tuaj yeem ua rau muaj kev puas tsuaj rau hauv cov ntawv thov uas yuav tsum tau ua kom ductility, ua rau nws tseem ceeb heev los tswj cov nyiaj cementite hauv microstructure.
Kub stability: Cementite ruaj khov ntawm qhov kub siab, uas ua rau nws yog ib qho tseem ceeb hauv theem siab ntawm -kub siv, xws li hauv cov cuab yeej txiav thiab tuag.
Tshuaj muaj pes tsawg leeg: Raws li kev sib xyaw ntawm hlau thiab carbon, cementite tuaj yeem cuam tshuam cov hlau cov lus teb rau kev kho cua sov thiab nws cov kev ua tau zoo tag nrho hauv kev pabcuam.
Vim li cas Cementite tseem ceeb hauv Steel Production?
Cementite plays lub luag haujlwm tseem ceeb hauv kev txiav txim siab cov khoom siv ntawm cov hlau thiab cam khwb cia hlau. Nov yog qee qhov laj thawj tseem ceeb rau nws qhov tseem ceeb:
1. Microstructural Control
Lub xub ntiag thiab kev faib tawm ntawm cementite hauv microstructure cuam tshuam rau hardness, lub zog, thiab ductility ntawm steel. Los ntawm kev tswj kev tsim cov cementite los ntawm kev sib tsoo thiab kev kho cua sov, metallurgists tuaj yeem tsim cov khoom ntawm cov hlau rau cov ntawv thov tshwj xeeb.
2. Kev cuam tshuam rau kev hnav tsis kam
Cementite pab txhawb rau kev hnav tsis kam ntawm cov hlau, ua rau nws zoo tagnrho rau kev siv hauv cov cuab yeej thiab cov khoom uas muaj kev sib txhuam tseem ceeb thiab hnav. Piv txwv li, siab- carbon steels nrog cov ntsiab lus ntawm cov cementite ntau yog feem ntau siv rau hauv cov cuab yeej txiav thiab hnav- qhov chaw tiv taus.
3. Lub luag haujlwm hauv kev kho cua sov
Kev nkag siab txog lub luag haujlwm ntawm cementite yog qhov tseem ceeb thaum lub sijhawm kev kho cua sov ntawm cov hlau. Kev hloov pauv ntawm austenite mus rau pearlite lossis martensite ncaj qha cuam tshuam rau tus cwj pwm ntawm cementite, cuam tshuam rau cov khoom siv kho tshuab kawg ntawm cov khoom.
4. Kev cuam tshuam rau Alloy Development
Cementite kev sib cuam tshuam nrog lwm cov hlau alloying, xws li chromium, molybdenum, thiab manganese, pab kom muaj kev txhim kho qib siab - steels ua tau zoo. Cov ntsiab lus alloying no tuaj yeem hloov kho qhov ruaj khov thiab nag lossis daus ntawm cementite, txhim kho cov khoom siv tag nrho.
Yuav Ua Li Cas Cementite tuaj yeem tswj tau hauv kev ua hlau?
Kev tswj cov cementite hauv kev ua hlau muaj ntau txoj hauv kev, suav nrog:
Alloying: Ntxiv cov ntsiab lus alloying tshwj xeeb tuaj yeem cuam tshuam rau kev solubility ntawm cov pa roj carbon monoxide thiab tsim cov cementite, tso cai rau kev tsim cov microstructures.
Kev kho cua sov: Kho cov cua sov thiab cua txias thaum lub sij hawm kho cua sov tuaj yeem tswj cov nyiaj thiab kev faib tawm ntawm cementite hauv microstructure kawg.
Thermomechanical Txheej Txheem: Cov txheej txheem xws li dov thiab forging tuaj yeem hloov pauv kev faib cov cementite thiab txhim kho cov khoom siv ntawm cov hlau.
Xaus: Qhov Tseem Ceeb ntawm Cementite hauv Niaj Hnub Metallurgy
Hauv kev xaus, cementite yog ib qho tseem ceeb ntawm cov hlau microstructure, cuam tshuam nws cov hardness, lub zog, thiab tag nrho kev ua tau zoo. Kev nkag siab txog kev tsim, cov yam ntxwv, thiab lub luag haujlwm ntawm cementite tso cai rau cov neeg siv hlau ua kom zoo rau cov hlau rau ntau yam kev siv, los ntawm kev tsim kho mus rau kev siv cuab yeej. Raws li kev tshawb fawb hauv cov ntaub ntawv tshawb fawb txuas ntxiv mus, lub peev xwm los tswj cov cementite yuav ua rau txoj hauv kev rau kev txhim kho cov tshiab, siab - steels ua tau zoo uas ua tau raws li qhov xav tau ntawm cov kev sib tw niaj hnub engineering.
