Tempering ntawm Steel
Tempering yog txheej txheem kev kho cua sov uas lub tshuab ua haujlwm quenched rov qab rau qhov kub hauv qab A1, tuav rau lub sijhawm tshwj xeeb, thiab tom qab ntawd txias rau hauv chav tsev kub. quenched steel yuav tsum tsis txhob siv ncaj qha; nws yuav tsum tau tempering, uas txiav txim siab lub microstructure thiab cov khoom ntawm cov hlau thiab yog ib qho tseem ceeb ntawm kev kho cua sov kauj ruam.
Lub hom phiaj ntawm Tempering
Ua kom tiav Cov Khoom Siv Hluav Taws Xob uas xav tau
Tom qab quenching, lub workpiece muaj siab hardness tab sis tsis tshua muaj ductility thiab toughness. Txhawm rau ua kom tau raws li qhov xav tau ntawm kev ua haujlwm sib txawv rau ntau qhov chaw, tempering yog siv los hloov kho lub microstructure quenched, kho hardness, thiab txo brittleness, uas ua rau cov khoom xav tau ntawm lub workpiece.
Yuav Stabilize Workpiece Dimensions
Lub martensite thiab khaws cia austenite tsim thaum lub sij hawm quenching yog cov qauv tsis ruaj khov uas yuav decompose nyob rau lub sij hawm, ua rau qhov loj me thiab cov duab hloov. Tempering hloov cov quenched microstructure mus rau hauv ib qho ruaj khov, kom ntseeg tau tias lub workpiece tuav nws qhov ntev thiab cov duab thaum siv.
Txhawm rau txo lossis tshem tawm cov kev ntxhov siab sab hauv los ntawm quenching
Quenching induces tseem ceeb hauv kev ntxhov siab. Yog tias tsis tau sai sai los ntawm tempering, cov kev ntxhov siab no tuaj yeem ua rau lub workpiece deform los yog tawg.
Transformations Thaum Tempering ntawm Quenched Steel
Quenched martensite thiab khaws cia austenite yog metastable theem uas decompose rau hauv ferrite thiab carbides thaum tempered ntawm chav tsev kub mus rau hauv qab A1. Cov kev hloov pauv tshwj xeeb nyob ntawm qhov kub thiab txias:
Decomposition ntawm Martensite (tsawg dua los yog sib npaug rau 200 degree)
Thaum tempered qis dua 80 degree, tsis muaj kev hloov pauv loj ntawm microstructural tshwm sim, tshwj tsis yog rau pawg ntawm carbon atoms hauv martensite. Ntawm 80℃thiab 200 degree, martensite pib decompose, nrog carbon atoms precipitating li ε-carbides (Fe2.4C), txo cov pa roj carbon supersaturation nyob rau hauv martensite thiab txo tetragonality. Raws li qhov kub thiab txias tsis tshua muaj, tsuas yog ib feem ntawm cov pa roj carbon ntau dhau, tawm hauv martensite raws li cov kua dej supersaturated carbon hauv -Fe. Cov nplua ε-carbides tau tawg mus rau hauv qhov sib cuam tshuam ntawm supersaturated - cov kua dej khov, tswj kev sib raug zoo (qhov twg cov atoms ntawm theem ciam teb yog sib koom los ntawm ob lub siv lead ua lattices). Qhov no microstructure, uas muaj tsawg supersaturated -solid tov thiab ε-carbides, hu ua tempered martensite. Vim yog qhov zoo thiab muaj qhov sib txawv ntawm cov ε-carbides, qhov nyuaj ntawm cov hlau tsis txo qis thaum tempered qis dua 200 degree. Txawm li cas los xij, nag lossis daus ntawm ε-carbides txo cov lattice distortion, txo qis quenching kev ntxhov siab thiab ua rau me ntsis ntxiv cov yas thiab toughness ntawm cov hlau.
Decomposition ntawm Retained Austenite (200℃-300 degree)
Khaws austenite zoo ib yam li undercooled austenite, yog li nws cov khoom hloov pauv hloov pauv zoo ib yam li cov uas tsis muaj austenite nyob rau hauv qhov kub zoo sib xws, tsim martensite, bainite, lossis pearlite nyob ntawm qhov kub thiab txias.
Thaum cov hlau yog tempered ntawm 200℃thiab 300 degree, martensite tseem decompose, thiab khaws cia austenite pib hloov mus rau hauv qis bainite (200℃-300℃yog qis dua bainite transformation ntau). Ntawm qhov ntsuas kub no, quenching kev ntxhov siab ntxiv txo qis, tab sis hardness tsis poob qis.
Kev hloov pauv ntawm Carbides (250℃-450 degree)
Thaum tempered saum 250 degree, qhov muaj peev xwm diffusion ntawm carbon atoms ua rau ε-carbides maj mam hloov mus rau hauv cov cementite ruaj khov. Los ntawm 450 degree, tag nrho ε-carbides hloov mus rau hauv cov cementite tawg heev. Cov nag lossis daus tas li ntawm cov pa roj carbon monoxide txo qis cov ntsiab lus ntawm cov pa roj carbon monoxide hauv - cov kua tshuaj rau nws cov qib sib npaug, tig mus rau hauv ferrite, txawm tias nws tseem muaj rab koob - zoo li hauv cov duab. Cov qauv no, tsim los ntawm rab koob-zoo li ferrite thiab cov cementite tawg heev, hu ua tempered troostite. Tempered troostite qauv ntawm 45 steel yog qhia nyob rau hauv daim duab hauv qab no. Nyob rau ntawm no, lub hardness ntawm cov hlau txo, thiab nws toughness thiab plasticity nce ntxiv, nrog quenching kev nyuaj siab yuav luag tshem tawm.
Aggregation thiab Loj hlob ntawm Cementite thiab Recrystallization ntawm Ferrite (450℃-700 degree)
Tshaj li 450 degree, cov cementite tawg heev maj mam spheroidizes rau hauv cov khoom zoo, thiab thaum kub nce, cov khoom no loj tuaj. Ib txhij, ferrite pib recrystallize ntawm 500℃thiab 600 degree, hloov los ntawm lath lossis rab koob-zoo li cov duab rau hauv cov nplej ntau ntau.
Cov qauv no, muaj cov cementite granular faib rau ntawm polygonal ferrite matrix, hu ua tempered sorbite. Tempered sorbite qauv ntawm 45 steel yog qhia nyob rau hauv daim duab hauv qab no. Yog tias qhov kub thiab txias ntxiv mus rau 650℃-A1, granular cementite coarsens, tsim cov microstructure ntawm polygonal ferrite thiab loj dua granular cementite, hu ua tempered pearlite.
Kev hloov pauv ntawm quenched steel thaum lub sij hawm tempering tshwm sim ntau qhov kub thiab txias. Txawm nyob rau tib qhov kub thiab txias, ntau hom kev hloov pauv tuaj yeem tshwm sim. Cov khoom ntawm tempered steel nyob ntawm cov kev hloov microstructural, uas, nyob rau hauv lem, cuam tshuam nws cov neeg kho tshuab kev ua tau zoo. Feem ntau, thaum lub tempering kub nce, lub zog thiab hardness txo thaum ductility thiab toughness txhim kho, nrog rau cov kev hloov no ua ntau pronounced nyob rau hauv siab kub.
Hom thiab kev siv ntawm Tempering
Qhov tseem ceeb tshaj plaws uas txiav txim siab steel lub microstructure thiab cov khoom yog qhov kub thiab txias. Tempering tau muab faib ua peb hom raws li qhov kub thiab txias thiab ua rau microstructure:
Tsawg-Tshav Kub Kub (150℃-250 degree)
Tsawg-kub tempering tsim tempered martensite. Lub hom phiaj yog khaws cov siab hardness thiab hnav tsis kam ntawm quenched steel thaum txo kev ntxhov siab thiab brittleness, thiab txhim kho ductility thiab toughness. Txoj kev no tsuas yog siv rau siab - carbon thiab alloy steels hauv cov cuab yeej txiav, ntsuas cov cuab yeej, txias stamping tuag, dov bearings, carburized qhov chaw, thiab nto-quenched qhov chaw. Lub hardness tom qab tempering yog feem ntau ntawm 58-64 HRC.
Nruab nrab-Tsub Tempering (350℃-500 degree)
Txoj kev no yields tempered troostite. Nws lub hom phiaj yog kom ua tiav cov txiaj ntsig siab, elastic txwv, thiab tseem ceeb toughness. Nruab nrab-kub tempering feem ntau yog siv rau ntau yam elastic Cheebtsam thiab kub- ua hauj lwm tuag. Lub hardness tom qab tempering feem ntau yog li ntawm 35-50 HRC.
Siab -Tsov Kub Kub (500℃-650 degree)
Txoj kev no ua rau tempered sorbite. Lub hom phiaj yog kom ua tiav qhov sib npaug ntawm lub zog, hardness, ductility, thiab toughness. Thaum quenching thiab siab -kub tempering tau ua ke, cov txheej txheem feem ntau hu ua "quenching thiab tempering." Nws yog dav siv rau cov khoom siv tseem ceeb hauv kev tsim cov tsheb, tsheb laij teb, thiab cov cuab yeej siv tshuab (xws li txuas cov pas nrig, studs, gears, thiab kis tau tus mob). Lub hardness tom qab tempering feem ntau yog li ntawm 200-330 HBW.
Txawm hais tias qhov hardness qhov tseem ceeb ntawm cov hlau tom qab normalizing thiab quenching -tempering yog qhov zoo sib xws, cov khoom siv tseem ceeb hauv kev tsim khoom feem ntau yog quenching -tempering es tsis yog normalizing. Qhov no yog vim hais tias lub microstructure ntawm tempered sorbite muaj granular cementite, whereas sorbite tau los ntawm normalizing muaj lamellar cementite. Yog li ntawd, quenched thiab tempered steel tsis tsuas yog muaj zog dua, tab sis kuj muaj zoo ductility thiab toughness piv rau lub normalized lub xeev.
quenching thiab tempering tuaj yeem ua cov txheej txheem kho cua sov zaum kawg lossis raws li kev kho mob ua ntej ua ntej qhov tawv tawv thiab tshuaj kho cua sov. Txij li thaum lub hardness ntawm tempered steel tsis siab, nws tso cai rau kom yooj yim machining thiab tsawg nto roughness qhov tseem ceeb.
Ntxiv rau peb txoj kev tempering no, qee qhov siab - alloy steels tau siab - kub softening tempering ntawm 20℃-40℃hauv qab A1 kom tau tempered pearlite ua lwm txoj rau spheroidizing annealing.
Txhawm rau kom paub meej txog kev hloov pauv microstructural thaum tempering, lub workpiece yuav tsum tau tuav ntawm qhov kub thiab txias rau lub sijhawm txaus, feem ntau ntawm 1 mus rau 3 teev, nyob ntawm cov khoom, kub, thickness, load, thiab cua sov txoj kev. Txoj kev ua kom txias tom qab tempering tsis cuam tshuam rau kev ua haujlwm ntawm cov hlau, tab sis kom tsis txhob muaj kev ntxhov siab tshiab, cov khoom ua haujlwm feem ntau maj mam txias hauv huab cua tom qab tempering.
Tiv tauj peb
Yog xav paub ntxiv, thov hu rau peb ntawmmetal@welongpost.com.
