Vim li cas ho tsis tuaj yeem Weld Ductile Iron?

Vim li cas ho tsis tuaj yeem welded hlau?**

** Taw qhia

Ductile hlau, tseem hu ua nodular hlau los yog spheroidal graphite hlau, yog ib hom cam khwb cia hlau uas yog dav siv nyob rau hauv ntau yam industries vim nws txhua yam khoom thiab versatility. Nws muaj kev sib xyaw ua ke zoo ntawm lub zog, toughness, thiab hnav tsis kam, ua rau nws haum rau cov ntawv thov uas xav tau cov ntaub ntawv ua haujlwm siab. Txawm li cas los xij, ib qho kev txwv ntawm cov hlau tsis zoo yog nws qhov nyuaj hauv kev vuam. Tsab ntawv xov xwm no yuav tshawb txog cov laj thawj tom qab cov teeb meem cuam tshuam nrog vuam cov hlau thiab sib tham txog lwm txoj hauv kev los koom nrog cov khoom siv no.

Nkag siab Cov Hlau Hlau

Ductile hlau muab nws lub npe los ntawm qhov tseeb tias nws nthuav tawm ductility, tsis zoo li cov hlau cam khwb cia, uas yog nkig. Lub xub ntiag ntawm graphite nodules, uas ua raws li kev ntxhov siab concentrators, ua rau cov hlau nplaum kom nqus tau lub zog thiab deform plastically ua ntej fracturing. Cov cuab yeej no ua rau nws tiv taus kev tawg thiab muab kev cuam tshuam zoo dua piv rau lwm cov cam khwb cia hlau.

Cov Kev Sib Tw ntawm Vuam Cov Hlau Hlau

Txawm hais tias nws muaj ntau qhov zoo, cov hlau nplaum ua rau muaj teeb meem loj thaum nws los txog rau vuam. Lub ntsiab yog vim li cas rau qhov nyuaj no yog nws muaj pes tsawg leeg, microstructure, thiab tsim ntawm brittle theem thaum vuam.

Cov ntsiab lus carbon siab

Cov hlau nplaum muaj cov pa roj carbon ntau dua li lwm hom cam khwb cia hlau, feem ntau yog li ntawm 2.2% mus rau 4.0%. Cov pa roj carbon ntau ntxiv ua rau cov khoom siv lub zog tab sis kuj ua rau cov theem nyuaj thiab nkig, xws li cementite (Fe3C). Cov theem no tuaj yeem ua rau tawg thiab txo cov ductility nyob rau hauv qhov chaw kub ntxhov (HAZ) thaum vuam.

Microstructure

Lub microstructure ntawm ductile hlau muaj graphite nodules embedded nyob rau hauv ib tug ferritic los yog pearlitic matrix. Lub xub ntiag ntawm cov nodules qhia heterogeneity, ua rau muaj teeb meem thaum vuam. Cov ntsiab lus ntawm cov pa roj carbon ntau hauv matrix tuaj yeem ua rau tsim cov theem nkig, uas ua rau txo qis weldability.

Brittle Phase Tsim

Thaum ductile hlau raug rau siab thermal cycling thaum lub sij hawm vuam, cov ntsiab lus carbon nyob rau hauv cov khoom yuav hloov mus rau hauv martensite. Martensite yog ib theem nyuaj thiab nkig uas tsis muaj qhov ductility ntawm cov khoom qub. Yog li ntawd, qhov tsim ntawm martensite nyob rau hauv HAZ tuaj yeem cuam tshuam lub zog thiab toughness ntawm vuam.

Tiv thaiv thiab txo qis cov teeb meem vuam

Vim muaj cov teeb meem cuam tshuam nrog vuam cov hlau, qee qhov kev ceev faj thiab cov txheej txheem yuav tsum tau ua haujlwm kom txo tau qhov kev pheej hmoo ntawm kev tawg thiab brittleness. Cov tswv yim no suav nrog preheating, tom qab vuam kev kho cua sov, thiab siv cov txheej txheem vuam tshwj xeeb.

Preheating

Preheating suav nrog nce qhov kub ntawm lub hauv paus hlau ua ntej vuam, uas yuav pab txo qis thermal gradients, txo cov kev ntxhov siab, thiab ua kom txias txias. Los ntawm preheating cov ductile hlau, qhov kev pheej hmoo ntawm kev tsim nkig theem, xws li martensite, yog txo, txhim khu lub weldability ntawm cov khoom.

Kev kho cua sov tom qab Weld

Kev kho cua sov tom qab vuam (PWHT) yog lwm txoj hauv kev zoo los txo qhov kev pheej hmoo cuam tshuam nrog vuam vuam hlau. PWHT suav nrog cua sov cov qauv welded mus rau qhov kub thiab txias thiab tuav nws rau qee lub sijhawm. Cov txheej txheem no tso cai rau cov txheej txheem microstructure mus rau kev tswj hwm kev hloov pauv, tshem tawm cov kev ntxhov siab seem thiab tempering txhua theem nkig tsim thaum vuam.

Cov txheej txheem vuam tsim nyog

Qee cov txheej txheem vuam yog tsim nyog rau cov hlau nplaum vim lawv muaj peev xwm tswj tau cov cua sov nkag thiab txo qis thermal stresses. Ib txoj kev siv feem ntau yog shielded hlau arc vuam (SMAW), tseem hu ua stick welding. SMAW tso cai rau kev tswj xyuas qhov kub thiab txias qeeb, txo qhov tsim ntawm nkig theem.

Lwm cov txheej txheem nquag ua haujlwm yog roj tungsten arc vuam (GTAW) lossis tungsten inert gas (TIG) vuam. Cov txheej txheem TIG siv cov khoom siv tsis siv tungsten electrode los tsim cov arc thiab yuav tsum tau muab cov khoom siv los tsim cov kev sib txuas. Kev siv cov khoom siv muab tub lim tsim nyog yog qhov tseem ceeb rau kev tswj xyuas qhov kev ncaj ncees ntawm cov hlau.

Lwm txoj hauv kev los koom nrog Cov Hlau Hlau

Xav txog cov kev sib tw vuam cuam tshuam nrog cov khoom siv hlau, lwm txoj hauv kev rau kev koom nrog cov khoom siv no tau txais kev pom zoo hauv ntau qhov kev lag luam. Lwm txoj hauv kev no suav nrog kev sib txuas ua ke, mechanical fastening, thiab brazing.

Adhesive Bonding

Adhesive bonding yog siv cov nplaum nplaum uas muaj zog heev los koom nrog ob qhov chaw. Txoj kev no muab lwm txoj hauv kev zoo tshaj plaws rau vuam, vim nws tsis tas yuav tsum tau siv qhov kub thiab txias, txo qhov kev pheej hmoo ntawm distortion, thiab ua tiav cov kev ntxhov siab tsis sib xws. Adhesive bonding yog qhov tshwj xeeb tshaj yog rau kev koom nrog cov duab sib txawv lossis cov khoom sib txawv.

Mechanical Fastening

Mechanical fastening txoj kev, xws li bolts, ceev, thiab rivets, muab ib tug txhim khu kev qha txhais tau tias ntawm kev koom tes ductile hlau Cheebtsam. Cov txheej txheem no zam qhov kev xav tau ntawm cov txheej txheem kub kub thiab tuaj yeem yooj yim ua raws li cov duab sib txawv thiab ntau thiab tsawg. Txawm hais tias mechanical fastening tuaj yeem ua rau muaj kev ntxhov siab ntau, kev xav tsim tsim nyog tuaj yeem txo qhov teeb meem no.

Brazing

Brazing yog ib qho txheej txheem sib koom ua ke uas siv cov hlau muab tub lim nrog qhov qis qis dua li cov khoom siv hauv paus. Cov hlau muab tub lim yog rhuab saum nws lub melting point tab sis hauv qab lub melting point ntawm lub hauv paus hlau thiab ces muab faib mus rau lub sib koom tes los ntawm capillary kev txiav txim. Brazing muab txoj hauv kev zoo ntawm kev sib koom ua ke ntawm cov hlau nplaum vim nws txo qis cov tswv yim cua sov thiab zam kev tsim cov theem nkig.

Xaus

Hauv kev xaus, cov teeb meem cuam tshuam nrog vuam cov hlau yog feem ntau vim nws cov ntsiab lus carbon siab, microstructure, thiab tsim cov nkig theem thaum vuam. Txhawm rau kov yeej cov teeb meem no, preheating, tom qab vuam kev kho cua sov, thiab kev siv cov txheej txheem vuam tsim nyog raug pom zoo. Xwb, nplaum nplaum, mechanical fastening, thiab brazing tuaj yeem suav tias yog lwm txoj hauv kev rau kev koom nrog cov hlau nplaum. Nkag siab txog cov kev txwv no thiab kev siv cov txheej txheem tsim nyog yuav ua kom muaj kev sib koom ua tiav ntawm cov khoom siv hlau hlau thaum tuav lawv cov khoom siv kho tshuab.