Muaj ntau ntau txoj kev kho cua sov rau cov hlau ductile.
Nyob rau hauv cov qauv ntawm cov hlau ductile, cov graphite yog kheej kheej, thiab nws cov tsis muaj zog thiab kev puas tsuaj rau lub matrix yog tsis muaj zog tshaj li ntawm flake graphite. Qhov kev ua tau zoo ntawm cov hlau nplaum feem ntau yog nyob ntawm cov qauv matrix, thiab qhov cuam tshuam ntawm graphite yog qhov thib ob. Kev txhim kho cov qauv matrix ntawm cov hlau nplaum los ntawm ntau yam kev kho cua sov tuaj yeem txhim kho nws cov khoom siv hluav taws xob kom sib txawv. Vim yog cov tshuaj lom neeg muaj pes tsawg leeg, tus nqi cua txias, tus neeg sawv cev spheroidizing thiab lwm yam, cov qauv sib xyaw ntawm ferrite + pearlite + cementite + graphite feem ntau tshwm sim hauv cov qauv cam khwb cia, tshwj xeeb tshaj yog nyob rau ntawm phab ntsa nyias ntawm cov casting. Lub hom phiaj ntawm kev kho cua sov yog kom tau txais cov qauv tsim nyog thiab yog li txhim kho cov khoom siv kho tshuab.
Feem ntau siv cov kev kho cua sov rau cov hlau ductile yog raws li hauv qab no.
(1) Tsawg-kub graphitization annealing cua sov kub 720 ~ 760 ℃. Nws yog txias rau hauv qhov cub kom qis dua 500 ℃ thiab tom qab ntawd cua txias. Decompose eutectoid cementite kom tau cov hlau ductile nrog ferrite matrix los txhim kho toughness.
(2) High-temperature graphitization annealing ntawm 880 ~ 930 ℃, tom qab ntawd hloov mus rau 720 ~ 760 ℃ rau kev txuag hluav taws xob, thiab tom qab ntawd txias nrog lub qhov cub kom qis dua 500 ℃ thiab cua txias tawm ntawm qhov cub. Tshem tawm cov qauv dawb thiab tau txais cov hlau nplaum nrog ferrite matrix, uas txhim kho plasticity, txo hardness thiab nce toughness.
(3) Ua kom tiav austenitization thiab normalizing ntawm 880 ~ 930 ℃, txoj kev txias: cua txias, cua txias lossis cua txias. Txhawm rau txo kev ntxhov siab, ntxiv cov txheej txheem tempering: 500 ~ 600 ℃ kom tau pearlite + me me ntawm ferrite + spherical shape Graphite, uas ua rau muaj zog, hardness thiab hnav tsis kam.
(4) Ua tsis tiav austenitization, normalizing thiab cua sov ntawm 820 ~ 860 ℃, txoj kev txias: cua txias, cua txias lossis cua txias. Txhawm rau txo kev ntxhov siab, ntxiv cov txheej txheem tempering: 500 ~ 600 ℃ kom tau pearlite + ib qho me me ntawm cov hlau tawg Cov qauv lub cev ua tiav cov khoom siv zoo dua.
(5) quenching thiab tempering kev kho mob: cua sov ntawm 840 ~ 880 ° C, txias txoj kev: roj los yog dej txias, tempering kub tom qab quenching: 550 ~ 600 ° C, kom tau tempered sorbite qauv thiab txhim kho cov khoom siv kho tshuab.
(6) Isothermal quenching: Cua sov ntawm 840 ~ 880 ℃ thiab quenching hauv da dej ntsev ntawm 250 ~ 350 ℃ kom tau txais cov khoom siv kho tshuab, tshwj xeeb tshaj yog txhawm rau txhim kho lub zog, toughness thiab hnav tsis kam.
Thaum kho cua sov thiab cua sov, qhov kub ntawm cov casting nkag mus rau hauv lub cub tawg yog feem ntau tsawg dua 350 ° C. Cov cua kub ceev nyob ntawm qhov loj thiab qhov nyuaj ntawm cov casting, thiab xaiv ntawm 30 ~ 120 ° C / h. Qhov kub nkag rau hauv qhov cub rau qhov loj thiab qhov nyuaj yuav tsum qis dua thiab cov cua sov yuav tsum qeeb dua. Cov cua kub kub nyob ntawm cov qauv matrix thiab tshuaj muaj pes tsawg leeg. Lub sijhawm tuav yog nyob ntawm phab ntsa thickness ntawm lub casting.
Tsis tas li ntawd, ductile hlau castings kuj tuaj yeem ua rau saum npoo quenched siv cov zaus, nruab nrab zaus, nplaim taws thiab lwm txoj hauv kev kom tau txais siab tawv, hnav tsis kam thiab qaug zog. Nws kuj tseem tuaj yeem kho nrog mos nitriding los txhim kho qhov hnav tsis kam ntawm castings.
1.Quenching thiab tempering kev kho mob ntawm cov hlau ductile
Ductile castings yuav tsum muaj zog dua li cov kabmob, thiab cov hlau cam khwb cia feem ntau quenched thiab tempered ntawm qhov kub thiab txias. Cov txheej txheem yog: cua sov lub casting mus rau ib tug kub ntawm 860-900 ° C, insulating nws tso cai rau tag nrho cov thawj matrix rau austenitize, ces txias nws nyob rau hauv roj los yog molten ntsev kom tiav quenching, thiab ces cua sov thiab tswj nws ntawm 250-350. ° C rau tempering, thiab tus thawj matrix yog hloov dua siab tshiab rau hauv hluav taws martensite thiab khaws cia austenite qauv, tus kheej kheej kheej graphite zoo tsis hloov. Cov kev kho castings muaj siab hardness thiab tej yam toughness, khaws cov lubrication zog ntawm graphite, thiab tau txhim kho hnav tsis kam.
Ductile hlau castings, raws li ncej qhov chaw, xws li crankshafts thiab txuas rods ntawm diesel xyaw, yuav tsum tau txhua yam khoom siv nrog siab zog thiab zoo toughness. Cov cam khwb cia hlau qhov chaw yuav tsum tau quenched thiab tempered. Cov txheej txheem yog: cov cam khwb cia hlau yog rhuab mus rau ib tug kub ntawm 860-900 ° C thiab insulated rau austenitize lub matrix, ces txias nyob rau hauv roj los yog molten ntsev kom tiav quenching, thiab ces tempered ntawm ib tug kub ntawm 500-600 ° C rau. tau ib tug tempered troostite qauv. (Feem ntau tseem muaj me me ntawm cov ntshiab ferrite loj), thiab cov duab ntawm tus kheej kheej kheej graphite tseem tsis hloov. Tom qab kev kho mob, lub zog thiab toughness phim zoo thiab haum rau kev ua haujlwm ntawm cov ncej ncej.
2. Annealing ntawm ductile hlau los txhim kho toughness
Thaum lub sij hawm casting txheej txheem ntawm ductile hlau, zoo tib yam grey cam khwb cia hlau muaj ib tug loj whitening nyiam thiab loj sab hauv. Nws yog ib qho nyuaj kom tau txais ib qho ntshiab ferrite lossis pearlite matrix rau cam khwb cia hlau qhov chaw. Txhawm rau txhim kho cov ductility lossis toughness ntawm cam khwb cia hlau qhov chaw, cam khwb cia hlau yog feem ntau Cov khoom yog reheated rau 900-950 ° C thiab cia sov rau lub sij hawm txaus los ua high-temperature annealing, thiab ces txias rau 600 ° C thiab txias tawm. ntawm qhov cub. Thaum lub sij hawm txheej txheem, cov cementite hauv matrix decomposes rau hauv graphite, thiab graphite yog precipitated los ntawm austenite. Cov graphites sib sau ua ke nyob ib puag ncig tus kheej kheej kheej graphite, thiab cov matrix tau hloov pauv tag nrho rau hauv ferrite.
Yog hais tias cov txheej txheem cam khwb cia yog tsim los ntawm (ferrite + pearlite) matrix thiab kheej kheej graphite, txhawm rau txhim kho lub zog, cov cementite hauv pearlite tsuas yog yuav tsum tau decomposed thiab hloov mus rau ferrite thiab kheej kheej graphite. Rau lub hom phiaj no, cov cam khwb cia hlau yuav tsum tau reheated. Tom qab insulated nce thiab nqis lub eutectoid kub ntawm 700-760 ℃, lub cub tawg yog txias rau 600 ℃ thiab ces txias tawm ntawm lub cub tawg.
3. Normalizing los txhim kho lub zog ntawm ductile hlau
Lub hom phiaj ntawm normalizing ductile hlau yog los hloov cov qauv matrix rau hauv cov qauv zoo pearlite. Cov txheej txheem yog rov ua kom cov hlau nplaum hlau nrog cov matrix ntawm ferrite thiab pearlite rau qhov kub ntawm 850-900 ° C. Thawj ferrite thiab pearlite yog hloov mus rau hauv austenite, thiab qee cov graphite kheej kheej yog yaj hauv austenite. Tom qab kev txuag hluav taws xob, cov cua txias austenite hloov mus rau hauv cov pearlite zoo, yog li lub zog ntawm cov ductile casting nce.
Post lub sij hawm: May-08-2024
