Kev Tshawb Fawb Txog Kev Tsim Thiab Kev Tawg Ntawm Phosphorus Segregation Hauv Carbon Structural Steel
Tam sim no, cov lus qhia dav dav ntawm cov hlau carbon hlau hlau rods thiab bars muab los ntawm cov chaw tsim khoom hauv tsev yog φ5.5-φ45, thiab qhov ntau dua yog φ6.5-φ30. Muaj ntau qhov xwm txheej zoo los ntawm kev sib cais phosphorus hauv cov hlau me me thiab cov khoom siv raw. Cia peb tham txog kev cuam tshuam ntawm kev sib cais phosphorus thiab kev tshuaj xyuas ntawm kev tsim cov kab nrib pleb rau koj qhov kev siv.
Qhov ntxiv ntawm phosphorus rau hlau tuaj yeem kaw qhov austenite theem thaj tsam hauv daim duab hlau-carbon theem. Yog li ntawd, qhov deb ntawm solidus thiab liquidus yuav tsum tau nthuav dav. Thaum cov hlau uas muaj phosphorus txias los ntawm kua mus rau khoom, nws yuav tsum dhau los ntawm ntau qhov kub thiab txias. Qhov nrawm ntawm phosphorus hauv hlau qeeb. Lub sijhawm no, cov hlau molten nrog qhov siab phosphorus concentration (qis melting point) tau sau rau hauv qhov sib txawv ntawm thawj cov dendrites khov, yog li tsim cov phosphorus sib cais.
Hauv cov txheej txheem txias lossis cov txheej txheem extrusion txias, cov khoom tawg feem ntau pom. Kev tshuaj xyuas metallographic thiab kev tshuaj xyuas ntawm cov khoom tawg qhia tau hais tias ferrite thiab pearlite tau faib ua cov kab, thiab ib daim hlau dawb tuaj yeem pom tseeb hauv lub matrix. Hauv ferrite, muaj cov kab sib xyaw ua ke ntawm cov xim grey sulfide ntawm cov kab ferrite matrix no. Cov qauv kab no tshwm sim los ntawm kev sib cais ntawm sulfur phosphide hu ua "dab kab". Qhov no yog vim tias thaj chaw nplua nuj phosphorus hauv thaj chaw uas muaj kev sib cais phosphorus hnyav tshwm sim dawb thiab ci. Vim yog cov ntsiab lus phosphorus siab ntawm txoj siv dawb thiab ci, cov ntsiab lus carbon hauv txoj siv dawb thiab ci uas muaj phosphorus-enriched raug txo qis lossis cov ntsiab lus carbon me me heev. Ua li no, cov siv lead ua ke ntawm cov slab casting txuas ntxiv mus rau hauv nruab nrab thaum lub sijhawm casting txuas ntxiv ntawm txoj siv phosphorus-enriched. . Thaum lub billet khov kho, austenite dendrites thawj zaug precipitated los ntawm cov hlau molten. Cov phosphorus thiab sulfur uas muaj nyob hauv cov dendrites no raug txo qis, tab sis cov hlau molten khov kho kawg yog nplua nuj nyob rau hauv phosphorus thiab sulfur impurity elements, uas khov kho nyob nruab nrab ntawm lub dendrite axis, vim muaj cov phosphorus thiab sulfur ntau, sulfur yuav tsim sulfide, thiab phosphorus yuav yaj hauv lub matrix. Nws tsis yooj yim rau diffuse thiab muaj cov nyhuv ntawm kev tso tawm carbon. Carbon tsis tuaj yeem yaj rau hauv, yog li nyob ib puag ncig cov phosphorus khoom khov kho kua (Cov sab ntawm ferrite dawb band) muaj cov pa roj carbon ntau dua. Cov khoom carbon ntawm ob sab ntawm ferrite siv, uas yog, ntawm ob sab ntawm thaj chaw phosphorus-enriched, feem tsim ib txoj siv nqaim, intermittent pearlite sib luag rau ferrite dawb siv, thiab cov ntaub so ntswg ib txwm nyob ib sab Cais. Thaum lub billet raug cua sov thiab nias, cov shafts yuav txuas ntxiv raws li kev coj ua dov. Nws yog qhov tseeb vim tias ferrite band muaj phosphorus siab, uas yog, qhov kev sib cais phosphorus loj ua rau muaj kev tsim ntawm cov qauv ferrite dav thiab ci, nrog cov hlau pom tseeb Muaj cov kab grey ntawm sulfide hauv cov kab dav thiab ci ntawm lub cev lub cev. Cov kab ferrite nplua nuj phosphorus no nrog cov kab ntev ntawm sulfide yog qhov peb feem ntau hu ua lub koom haum "ghost line" (saib Daim Duab 1-2).
Daim Duab 1 Hlau dab hauv cov hlau carbon SWRCH35K 200X
Daim Duab 2 Hlau dab hauv cov hlau carbon dawb Q235 500X
Thaum cov hlau kub dov, tsuav yog muaj phosphorus sib cais hauv billet, nws tsis yooj yim sua kom tau txais cov qauv microstructure sib xws. Ntxiv mus, vim muaj phosphorus sib cais hnyav, cov qauv "dab hlau" tau tsim, uas yuav txo cov khoom siv kho tshuab ntawm cov khoom siv.
Qhov kev sib cais ntawm phosphorus hauv cov hlau carbon yog ib txwm muaj, tab sis qib sib txawv. Thaum cov phosphorus raug sib cais hnyav (cov qauv "dab kab" tshwm sim), nws yuav coj cov teebmeem tsis zoo rau cov hlau. Nws yog qhov tseeb, qhov kev sib cais hnyav ntawm phosphorus yog qhov ua rau cov khoom tawg thaum lub sijhawm txias. Vim tias cov noob sib txawv hauv cov hlau muaj cov ntsiab lus phosphorus sib txawv, cov khoom muaj lub zog thiab qhov nyuaj sib txawv; ntawm qhov tod tes, nws kuj ua rau cov khoom tsim kev ntxhov siab sab hauv, nws yuav txhawb cov khoom kom yooj yim tawg sab hauv. Hauv cov khoom siv nrog cov qauv "dab hlau", nws yog qhov tseeb txo qis ntawm qhov nyuaj, lub zog, elongation tom qab tawg thiab txo qis thaj chaw, tshwj xeeb tshaj yog txo qis ntawm kev cuam tshuam toughness, uas yuav ua rau cov khoom siv txias brittleness, yog li cov ntsiab lus phosphorus thiab cov khoom siv ntawm cov hlau Muaj kev sib raug zoo heev.
Kev tshawb pom metallographic Hauv cov ntaub so ntswg "dab kab" hauv nruab nrab ntawm qhov pom, muaj ntau tus ntawm cov xim grey elongated sulfides. Cov khoom tsis yog hlau hauv cov hlau qauv feem ntau muaj nyob rau hauv daim ntawv ntawm oxides thiab sulfides. Raws li GB / T10561-2005 "Standard Grading Chart Microscopic Inspection Method rau Cov Ntsiab Lus ntawm Cov Khoom Tsis Yog Hlau hauv Hlau", Hom B inclusions raug vulcanized lub sijhawm no. Qib khoom ncav cuag 2.5 thiab siab dua. Raws li peb txhua tus paub, cov khoom tsis yog hlau yog qhov chaw ntawm cov kab nrib pleb. Lawv qhov muaj nyob yuav ua rau puas tsuaj rau qhov sib txuas thiab compactness ntawm cov hlau microstructure, thiab txo qhov intergranular zog ntawm hlau. Nws yog xav los ntawm qhov no tias qhov muaj sulfides nyob rau hauv "dab kab" ntawm cov qauv sab hauv ntawm cov hlau yog qhov chaw feem ntau rau kev tawg. Yog li ntawd, txias forging tawg thiab cua sov kho quenching tawg hauv ntau qhov chaw tsim khoom fastener yog tshwm sim los ntawm ntau tus ntawm lub teeb grey slender sulfides. Qhov tshwm sim ntawm cov xov tsis zoo no ua rau puas tsuaj rau cov khoom siv hlau thiab ua rau muaj kev pheej hmoo ntawm kev kho cua sov. Cov "xov dab" tsis tuaj yeem tshem tawm los ntawm kev ua kom zoo li qub, thiab lwm yam, thiab cov khoom tsis huv yuav tsum tau tswj hwm nruj me ntsis los ntawm cov txheej txheem smelting lossis ua ntej cov khoom siv raw nkag mus rau hauv lub Hoobkas.
Cov khoom tsis yog hlau raug muab faib ua alumina (hom A) silicate (hom C) thiab spherical oxide (hom D) raws li lawv cov khoom sib xyaw thiab kev hloov pauv. Lawv qhov muaj nyob txiav tawm qhov sib txuas ntawm cov hlau, thiab cov qhov lossis cov kab nrib pleb raug tsim tom qab tev tawm. Nws yooj yim heev los tsim qhov chaw ntawm cov kab nrib pleb thaum lub sijhawm txias thiab ua rau muaj kev ntxhov siab thaum lub sijhawm kho cua sov, ua rau muaj kev tawg quenching. Yog li ntawd, cov khoom tsis yog hlau yuav tsum tau tswj hwm nruj me ntsis. Cov qauv hlau tam sim no GB / T700-2006 "Carbon Structural Steel" thiab GB / T699-2016 "High-quality Carbon Structural Steel" tsis ua kom meej meej cov kev cai rau cov khoom tsis yog hlau. . Rau cov khoom tseem ceeb, cov kab ntxhib thiab zoo ntawm A, B, thiab C feem ntau tsis ntau tshaj 1.5, thiab cov kab ntxhib thiab zoo ntawm D thiab Ds tsis ntau tshaj 2.
Lub sijhawm tshaj tawm: Lub Kaum Hli-21-2021
