Kev tshuaj xyuas ntawm Kev Tsim thiab Kev Sib Cuag ntawm Phosphorus Segregation hauv Carbon Structural Steel

Kev tshuaj xyuas ntawm Kev Tsim thiab Kev Sib Cuag ntawm Phosphorus Segregation hauv Carbon Structural Steel

Tam sim no, cov kev qhia tshwj xeeb ntawm cov qauv hlau steel hlau rods thiab cov tuav tau muab los ntawm cov tsev steel mills yog φ5.5-φ45, thiab qhov loj dua yog φ6.5-φ30. Muaj ntau yam xwm txheej zoo tshwm sim los ntawm kev sib cais ntawm phosphorus hauv cov hlau me me thiab cov khoom siv raw khoom. Cia peb tham txog kev cuam tshuam ntawm phosphorus cais thiab kev tsom xam ntawm kev tsim cov kab nrib pleb rau koj siv.

Qhov sib ntxiv ntawm phosphorus rau hlau tuaj yeem kaw qhov austenite theem cheeb tsam hauv daim duab hlau-carbon theem. Yog li ntawd, qhov kev ncua deb ntawm lub solidus thiab lub liquidus yuav tsum tau loj. Thaum phosphorus-muaj hlau yog txias los ntawm cov kua rau cov khoom, nws yuav tsum dhau los ntawm ntau qhov kub thiab txias. Qhov diffusion tus nqi ntawm phosphorus hauv steel yog qeeb. Lub sij hawm no, molten hlau nrog ib tug siab phosphorus concentration (tsawg melting point) yog sau nyob rau hauv qhov khoob ntawm thawj solidified dendrites, yog li tsim phosphorus cais.

Nyob rau hauv lub taub hau txias lossis txias extrusion txheej txheem, cov khoom tawg yog feem ntau pom. Kev tshuaj xyuas metallographic thiab kev soj ntsuam ntawm cov khoom tawg tau qhia tias cov ferrite thiab pearlite raug faib rau hauv cov hlua, thiab ib daim kab xev ntawm cov hlau dawb tuaj yeem pom meej hauv cov matrix. Nyob rau hauv lub ferrite, muaj intermittent band-shaped lub teeb grey sulfide inclusions ntawm no band-shaped ferrite matrix. Cov qauv band-shaped 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 nyob rau hauv cheeb tsam uas muaj phosphorus loj segregation tshwm dawb thiab ci. Vim yog cov ntsiab lus phosphorus siab ntawm txoj siv tawv dawb thiab ci, cov ntsiab lus carbon hauv phosphorus-enriched dawb thiab ci siv yog txo los yog cov ntsiab lus carbon tsawg heev. Nyob rau hauv txoj kev no, lub columnar muaju ntawm cov nruam casting slab tsim mus rau qhov chaw thaum lub sij hawm nruam casting ntawm phosphorus-enriched siv. . Thaum lub billet yog solidified, austenite dendrites yog thawj precipitated los ntawm cov hlau molten. Cov phosphorus thiab sulfur muaj nyob rau hauv cov dendrites no raug txo, tab sis qhov kawg solidified molten hlau yog nplua nuj nyob rau hauv phosphorus thiab sulfur impurity ntsiab, uas solidify nyob rau hauv nruab nrab ntawm lub dendrite axis, vim hais tias ntawm cov ntsiab lus siab ntawm phosphorus thiab sulfur, sulfur yuav tsim sulfide, thiab phosphorus yuav yaj hauv matrix. Nws tsis yooj yim rau diffuse thiab muaj cov nyhuv ntawm cov pa roj carbon. Cov pa roj carbon tsis tuaj yeem yaj hauv, yog li nyob ib puag ncig cov tshuaj phosphorus (Cov sab ntawm ferrite dawb band) muaj cov ntsiab lus carbon ntau dua. Cov pa roj carbon monoxide ntawm ob sab ntawm txoj siv ferrite, uas yog, ntawm ob sab ntawm phosphorus-enriched cheeb tsam, raws li ib tug nqaim, intermittent pearlite siv thaum uas tig mus rau lub ferrite dawb siv, thiab cov ntaub so ntswg uas nyob ib sab sib cais. Thaum lub billet yog rhuab thiab nias, lub shafts yuav txuas mus rau lub dov kev taw qhia. Nws yog precisely vim hais tias cov ferrite band muaj phosphorus siab, uas yog, phosphorus loj segregation ua rau tsim ib tug loj broad thiab kaj ferrite band qauv, nrog pom tseeb hlau muaj lub teeb grey strips ntawm sulfide nyob rau hauv lub broad thiab kaj band. cev. Qhov no phosphorus-nplua nuj ferrite band nrog ntev strips ntawm sulfide yog qhov peb feem ntau hu ua "dab kab" lub koom haum (saib daim duab 1-2).

Analysis of Formation and Cracking of Phosphorus Segregation in Carbon Structural Steel02
Daim duab 1 Dab hlau hauv carbon steel SWRCH35K 200X

Analysis of Formation and Cracking of Phosphorus Segregation in Carbon Structural Steel01
Daim duab 2 Dab hlau hauv cov pa roj carbon steel Q235 500X

Thaum cov hlau yog kub dov, tsuav yog muaj phosphorus cais nyob rau hauv lub billet, nws yog tsis yooj yim sua kom tau ib tug uniform microstructure. Ntxiv mus, vim muaj kev sib cais ntawm phosphorus hnyav, "ghost wire" qauv tau tsim, uas yuav ua rau txo qis cov khoom siv ntawm cov khoom siv. .

Kev sib cais ntawm phosphorus hauv carbon hlau yog qhov sib txawv, tab sis qhov degree sib txawv. Thaum cov phosphorus raug cais nruj heev (cov qauv "dab kab" tshwm), nws yuav ua rau muaj kev cuam tshuam tsis zoo rau cov hlau. Pom tseeb, qhov sib cais hnyav ntawm phosphorus yog qhov ua txhaum ntawm cov khoom tawg thaum lub caij txias. Vim tias cov nplej sib txawv hauv cov hlau muaj cov ntsiab lus phosphorus sib txawv, cov khoom muaj zog sib txawv thiab hardness; ntawm qhov tod tes, nws tseem ua rau cov khoom tsim kev ntxhov siab sab hauv, nws yuav txhawb nqa cov khoom kom muaj kev cuam tshuam sab hauv. Nyob rau hauv cov ntaub ntawv nrog "ghost wire" qauv, nws yog precisely txo hardness, lub zog, elongation tom qab tawg thiab txo ntawm cheeb tsam, tshwj xeeb tshaj yog txo cov kev cuam tshuam toughness, uas yuav ua rau lub txias brittleness ntawm cov khoom, yog li cov ntsiab lus phosphorus. thiab cov yam ntxwv ntawm steel muaj kev sib raug zoo heev.

Metallographic nrhiav tau nyob rau hauv "dab kab" cov ntaub so ntswg nyob rau hauv nruab nrab ntawm lub teb ntawm saib, muaj ib tug loj tus naj npawb ntawm lub teeb grey elongated sulfides. Cov non-metallic inclusions nyob rau hauv structural steel mas muaj nyob rau hauv daim ntawv ntawm oxides thiab sulfides. Raws li GB/T10561-2005 "Standard Grading Chart Microscopic Inspection Method for the Content of Non-metallic Inclusions in Steel", hom B suav nrog yog vulcanized nyob rau lub sijhawm no Cov khoom siv qib nce mus txog 2.5 thiab siab dua. Raws li peb txhua tus paub, non-metallic inclusions yog qhov muaj peev xwm ntawm cov kab nrib pleb. Lawv lub neej yuav ua rau muaj kev puas tsuaj loj rau kev txuas ntxiv thiab kev cog lus ntawm cov hlau microstructure, thiab txo qis lub zog intergranular ntawm cov hlau. Nws yog inferred los ntawm qhov no hais tias lub xub ntiag ntawm sulfides nyob rau hauv lub "dab kab" ntawm lub sab hauv cov qauv ntawm cov hlau yog qhov zoo tshaj plaws qhov chaw rau tawg. Yog li ntawd, txias forging tawg thiab kev kho cua sov quenching kab nrib pleb nyob rau hauv ib tug loj tus naj npawb ntawm fastener ntau lawm qhov chaw yog tshwm sim los ntawm ib tug loj tus naj npawb ntawm lub teeb grey slender sulfides. Cov tsos ntawm cov weaves tsis zoo no rhuav tshem cov khoom txuas ntxiv ntawm cov hlau thiab ua rau muaj kev pheej hmoo ntawm kev kho cua sov. Cov "dab xov" tsis tuaj yeem raug tshem tawm los ntawm normalizing, thiab lwm yam, thiab cov ntsiab lus impurity yuav tsum nruj me ntsis tswj los ntawm cov txheej txheem smelting los yog ua ntej cov ntaub ntawv raw nkag mus rau hauv lub Hoobkas.

Cov non-metallic inclusions muab faib ua alumina (hom A) silicate (hom C) thiab kheej kheej oxide (hom D) raws li lawv muaj pes tsawg leeg thiab deformability. Lawv lub neej txiav tawm qhov txuas ntxiv ntawm cov hlau, thiab cov pits los yog tawg yog tsim tom qab tev. Nws yog ib qho yooj yim heev los tsim cov kab nrib pleb thaum lub caij txias thiab ua rau muaj kev ntxhov siab thaum kho cua sov, ua rau quenching cracking. Yog li ntawd, tsis yog-hlau inclusions yuav tsum nruj me ntsis tswj. Cov hlau tam sim no GB / T700-2006 "Carbon Structural Steel" thiab GB / T699-2016 "High-quality Carbon Structural Steel" cov qauv tsis ua kom pom tseeb rau cov khoom tsis yog hlau. . Rau qhov tseem ceeb, cov kab ntxhib thiab nplua ntawm A, B, thiab C feem ntau tsis ntau tshaj 1.5, thiab D thiab Ds ntxhib thiab nplua kab tsis ntau tshaj 2.


Post lub sij hawm: Oct-21-2021