Hlau qhov chaw tuaj yeem tsim yuav luag txhua qhov tsis xws luag, tab sis vim lawv txoj kev tsim khoom, kev cai crystallization, casting zog thiab lwm yam casting alloys, ductile hlau feem ntau muaj qee qhov tsis xws luag.
Yog li dab tsi yog qhov tsis xws luag ntawm cov khoom siv hlau uas muaj feem xyuam rau tus neeg sawv cev spheroidizing, los yog dab tsi yog qhov tsis xws luag ntawm cov hlau txuas los ntawm tus neeg sawv cev spheroidizing?
(1) Dissimilation ntawm graphite npas: Lub dissimilation ntawm graphite npas ua rau tsis zoo graphite, xws li lumps, tadpoles, worms, horns los yog lwm yam uas tsis yog-spherical duab. Qhov no yog vim lub fact tias thaum spherical graphite loj hlob raws li hluav taws xob kev taw qhia, lub zos siv lead ua kev loj hlob hom thiab kev loj hlob tus nqi deviate los ntawm txoj cai loj hlob ib txwm.
(2) Graphite floating: Nyob rau hauv tuab-walled ductile hlau qhov chaw nrog hypereutectic muaj pes tsawg leeg, graphite-dense cheeb tsam feem ntau tshwm nyob rau sab saum toj ntawm lub pouring txoj hauj lwm, uas yog, qhov tshwm sim "floating thoob plaws". Qhov no yog vim qhov sib txawv ntawm graphite thiab molten hlau, thiab hypereutectic molten hlau ncaj qha Lub precipitated graphite yog tshwm sim los mus rau pem hauv ntej vim lub zog buoyancy.
(3) Whitening: Feem ntau, cov qauv ua kom zoo nkauj ntawm cov hlau cam khwb cia feem ntau tshwm sim rau ntawm qhov chaw, cov ces kaum ntse, seams, thiab lwm yam uas txias sai sai. Ntawm qhov tsis sib xws, whitening defect yog qhov opposite. Cov theem carbide tshwm nyob rau hauv nruab nrab ntawm qhov nruab nrab ntu ntawm cov casting thiab cov chaw kub. Ntu thiab lwm qhov chaw.
(4) Subcutaneous pinholes: Subcutaneous pinholes mas muaj hydrogen, tab sis kuj muaj me me ntawm carbon monoxide thiab nitrogen. Thaum cov ntsiab lus magnesium residual siab dhau lawm, nws kuj ua rau muaj kev nyiam nqus hydrogen los ntawm daim ntawv ntub dej, yog li ua rau muaj qhov tshwm sim ntawm subcutaneous pinholes. Tsis tas li ntawd, lub sij hawm nyob ntev ntawm spheroidized molten hlau kuj tuaj yeem ua rau cov pinholes ntau ntxiv.
(5) Shrinkage kab noj hniav: Shrinkage kab noj hniav feem ntau tshwm nyob rau hauv qhov kawg solidification qhov chaw thaum lub casting tiav (kub pob qij txha, kev sib txuas ntawm riser caj dab thiab lub casting, lub ces kaum sab hauv los yog kev sib txuas ntawm lub rooj vag puab thiab casting), uas yog muab zais rau hauv lub casting los yog ib lub qhov txuas rau saum npoo. Shrinkage porosity tshwm macroscopically ntawm qhov chaw kub, thiab cov qhov me me me me feem ntau cuam tshuam rau hauv lub qhov. Hais txog cov ntsiab lus spheroidizing, nws yog ib qho tsim nyog los tswj cov seem ntawm magnesium thiab cov av tsis tshua muaj siab kom tsis txhob siab dhau, uas muaj cov txiaj ntsig tseem ceeb ntawm kev txo qis macroscopic thiab microscopic shrinkage. Lub shrinkage nyiam yog yuav luag proportional rau spheroidizing ntsiab.
(6) Dub slag: Nws feem ntau tshwm sim nyob rau sab sauv ntawm lub casting (txoj hauj lwm pouring), thiab feem ntau yog muab faib ua lumpy, hlua zoo li thiab finely faib dub slag. Magnesium silicate, lub ntsiab tivthaiv ntawm dub slag, yog tsim los ntawm cov tshuaj tiv thaiv ntawm MgO thiab SiO2 nyob rau hauv molten hlau, thiab yog cuam tshuam los ntawm lawv cov txheeb ze cov ntsiab lus. Yog li ntawd, ib qho ntawm cov kev ntsuas los tswj cov slag dub yog kom txo cov seem ntawm magnesium (thaum ntxiv 0.15% magnesium, tag nrho cov nyiaj slag suav txog li 0.1% ntawm qhov hnyav. ntawm molten hlau). Cov seem uas tsis tshua muaj hauv ntiaj teb muaj kev sib raug zoo nrog cov pa oxygen thiab yog li tseem ceeb heev hauv kev txo cov slag dub. Muaj qhov pom tseeb los ntawm slag.
(7) Spheroidization poob: Qhov no yog vim hais tias spheroidized molten hlau nyob twj ywm rau lub sij hawm ntev, cov seem magnesium maj mam txo qis, lub slag tsis raug tshem tawm raws sij hawm, thiab leej faj yuav rov qab mus rau molten hlau, ua rau cov graphite nyob rau hauv lub solidified qauv. kom txo lossis txawm ploj mus, lwj mus rau hauv Irregular, worm-zoo li los yog flake graphite. Qhov kev poob qis ntawm spheroidization no muaj feem xyuam nrog cov ntsiab lus tsawg hauv lub ntiaj teb hauv spheroidizing tus neeg saib xyuas lossis tus nqi qis ntxiv ntawm tus neeg sawv cev spheroidizing. Txawm li cas los xij, nws tsis pom zoo kom nce cov nyiaj ntxiv tam sim ntawd vim tias cov ntsiab lus magnesium seem yog siab thiab cov nyiaj slag raug txo. thiab cementite yuav nce ntxiv, thiab hauv cov ntu tuab, cov pob graphite yuav degenerate rau hauv tadpole zoo li graphite.
