1. Thermal -} kev siv tshuab: tus neeg tsav tsheb tseem ceeb ntawm microstructure
a. Kev tswj cov dov & txias (thermo- mechanical tswj cov txheej txheem, TMCP)
Lub tshuab: TMCP cuam tshuam cov hlau uas muaj qhov kub tshwj xeeb (feem ntau 800-950 degree, lub Austenite recrystallization thaj tsam) thiab tswj cov posts- rolling txias tus nqi. Tus txheej txheem no ua kom cov hmoov av, uas tom qab hloov pauv mus ua kom tiav rau hauv ferrite {}} pumble nplej thaum txias.
Finer nplej =} zoo dua qis - kub nruj: Cov nplej uas muaj cov nplej uas muaj cov nplej zom ntau ntxiv, uas ua raws li cov nyom rau cov kev sib tsoo thaum muaj qhov kub thiab txias hluav taws xob thauj khoom. Piv txwv li, txo cov grerrite grain loj los ntawm 50 μm txog 10 μm muaj peev xwm ob npaug ntawm 0℃cuam tshuam lub zog ntawm s355j0wp (los ntawm qhov 28 J) J) J).
Cua Txias Zog Tswj: Qeeb txias (cua txias) zam qhov kev tsim ntawm nyuaj, parsension zoo li martensite lossis bainite, uas yog nquag mus rau brittle begiture ntawm tsawg kub. Conversely, overlyly txias txias (piv txwv li, dej quenching) tuaj yeem ntxias cov martile, tsa rau dastile- brimtle transitional hloov kub (DBTT) los ntawm 30-50 degree.
b. Normalizing cua sov kev kho mob
Daim Ntawv Thov Kev Thov: For thick S355J0WP plates (e.g., >20 hli), dov ib leeg yuav ua rau kev sib deev tsis sib luag hauv cov tub ntxhais. Li qub (cua sov rau 900-950 degree, cia li tuav homogenite, tom qab cua txias, thiab ua kom muaj kev phom sij ferrite {}} lub txivtter faib.
Cuam tshuam rau cov khoom: Nonmentized S3555J0WP Cov Khoom Taw Qhia Ua Haujlwm 15-20% Cov Khoom Siv Kub Ntau Tshaj Plaws Tsis Zoo, raws li nws cov khoom siv kub thiab cov kab mob PARDED) uas ua raws li cov kab tawg ntawm cov khoom tawg.
2. Kev tsis txaus siab sab hauv: zais cov kev pheej hmoo rau tsawg - kub tawm
a. Tsis - nws yog xim hlau suav nrog
Hom thiab cuam tshuam:
Sulfide suav (piv txwv li, MNS): Txawm tias cov ntsiab lus sulfur (tsawg dua los yog sib npaug rau 0.015%), seem ntawm cov kev coj ua) tsim kev ntxhov siab. Ntawm qhov kub tsawg zaus, cov suav no cais tawm los ntawm cov matrix, pib tawg uas propagate sai.
Oxide suav (piv txwv li, al₂o₃): Nyuaj, angular al₂o₃ suav nrog (los ntawm deoxidation) ua li "micro {{} Tsis txhob nqus cov peev xwm los nqus tej yam kev cuam tshuam lub zog.
Me quav: SivDaim duab muaj tshuaj calciumThaum lub sij hawm smelting hloov mns suav nrog rau hauv spherical CAS -} Caa ua si, uas tsis tshua pib pib. Qhov no tuaj yeem txhim kho qis qis - kub cuam tshuam nyuaj los ntawm 25-30%.
b. Porosity thiab Shrinkage Tej kab noj hniav
Tsim khoom: Porosity (cov roj npuas me me) lossis shrinkage kab noj hniav (los ntawm kev ua tsis tiav) daim ntawv thaum lub sijhawm ua pov thawj. Cov kev tsis haum no txo cov ntsaws lag luam - bearing ntxhov siab, lawv tuaj yeem loj hlob mus rau macroscopic tawg hauv qab kev ntxhov siab me ntsis.
Hloov: A porosity volume fraction of >0.5% tuaj yeem txo qis 0℃cuam tshuam lub zog ntawm s355j0wP los ntawm 40%, tsis muaj qhov "J0" qib kawm.
c. Residual kev nyuaj siab
Lub hauv paus: Residual stresses form during rolling (uneven cooling) or welding (thermal expansion/contraction). Tensile residual stresses (e.g., >200 MPa) nyob rau saum npoo lossis ze - Weld cheeb tsam sib txuas nrog tsawg- kub ua kom tawg.
Tus yam ntxwv: S35555j0wP daim hlau nrog cov siab nyob ntawm cov kev ntxhov siab tensile yuav nthuav tawm brittle fracture ntawm} 10 degree, txawm tias lawv dBTT yog theoretically 0 degree. Kev nyuaj siab kev pab txhawb kev pab txhawb (cua sov txog 550-600 degree, ces qeeb txias) tuaj yeem txo cov kev ntxhov siab tsawg los ntawm 60-80%, kho kom sov qis.
3. Cov Khoom Thickness: Ib qho Tseem Ceeb Rau Tsawg - kub ua tau zoo
a. Microsuctionation Heterogeneity
Thick plates (e.g., >30 hli) txias qeeb dua nyob rau hauv cov tub ntxhais tshaj li saum npoo thaum lub sij hawm dov, ua rau coarser nplej hauv cov tub ntxhais. Coarse nplej muaj qis tawv: 0℃cuam tshuam lub zog ntawm 40 lub hli} qis dua 10 hli} tuab tuab ntawm tib lub cev muaj pes tsawg leeg.
b. Triaxial kev ntxhov siab lub xeev
Nyob rau hauv kev cuam tshuam chaw thau khoom, tuab cov ntaub ntawv kev aTriaxial kev ntxhov siab lub xeev(Tensile muaj kev ntxhov siab hauv peb cov lus qhia) nyob ze qhov chaw cuam tshuam, whereas nyias cov ntaub ntawv muaj ntau cov kev ntxhov siab ntau yam kev ntxhov siab. Triaxial kev ntxhov siab txwv tsis pub muaj kev cuam tshuam zoo dua qub
Cov Qauv Xav Tau: ENG 10025-5 tso cai rau qis dua kev cuam tshuam rau cov phiaj s355j0wp daim hlau (piv txwv li 27-4 xyoos, vs. 34 j rau<16 mm) to account for this effect.
4. Kev Pabcuam Chaw: Ua kom nrawm degradation ntawm tsawg - cov khoom kub
a. Atmospheric corrosion
Lub tshuab: S3555J0wP kev cia siab rau ib qho ntom ntom, muaj cov txheej txheem xeb (muaj CU, CR Oxides) rau corrosion tsis kam. Txawm li cas los xij, nyob rau hauv txias, huab cua chaw ib puag ncig (piv txwv li thaj chaw txias txias), rov ua kom khov {} Ya raws penetrates qhov tawg, ua raupitting corrosion(zos cov hlau tsis zoo).
Cuam tshuam rau cov khoom: Pits ua raws li ntse tsis yog ovtches, feeb kev ntxhov siab. Ntawm tsawg kub, cov notches txo cov steel lub pob txha pob txha tawv tawv (KIC) los ntawm 20-30%, ua rau nws tsis ua tiav hauv kev ua tiav lossis kev thauj khoom zoo.
b. Hydrogen nqus (hydrogen embrittlement)
Qho tseem ceeb: Hydrogen tuaj yeem nkag S355j0wP thaum lub sijhawm vuam (noo noo hauv elovodes), pickling (acidic daws), lossis kev pabcuam acidic), lossis huab cua noo nrog h₂s). Ntawm tsawg kub, hydrogen atoms diffuse diffuse rau cov ciaj ciam av thiab ua hydrogen molecules (h₂), tsim kev kub siab sab hauv.
Lub txiv: Hydrogen embrittlement txo qis qis - kev cuam tshuam kub me me (piv txwv li kev ntxhov siab tsis tu ncua (piv txwv li qhov ntsuas kub) txawm nyob saum dBTTT.
