Q1: Dab tsi yog qhov tseem ceeb ntawm cov khoom siv tshuaj lom neeg ua kom muaj cov yeeb nkab Q420?
Cov ntsiab lus carbon ntawm Q420 cov yeeb nkab steel yog tswj tau hauv qab 0.18% kom ntseeg tau zoo weldability thiab nruj. Cov ntsiab lus manganese yog cov ntsiab lus tseem ceeb (1.00% rau 1.70%), thiab microolous ntsiab xws li niobium (ti) (ti) ntxiv rau kev txhim kho lub zog thiab cov qoob loo. Phosphorus thiab cov leeg sulfur cov ntsiab lus yog txhua qhov txwv rau hauv qab 0.030% (Q420d / e) los txo qhov txias thiab kub brittleness. Qee qib kawm qib qis Q420 (xws li Q420E) tseem yuav tsum muaj cov pa nitrogen (n) cov ntsiab lus ntawm tsawg dua lossis sib npaug rau 0.015% txhawm rau txhim kho qis-kub tougness. Cov khoom siv optimized no muab Q420 steel yeeb nkab kho tshuab cov cuab yeej siv tau zoo tshaj plaws, ua kom haum rau cov qauv hluav taws xob siab.
Q2: Cov khoom siv neeg kho tshuab ntawm Q420 cov yeeb nkab yog dab tsi? Q420 cov yeeb nkab steel muaj ib qho muaj zog ntau dua lossis sib npaug ntawm 420 MPA, thiab 680 MPa ntau dua lossis sib npaug rau 19%, ua kom muaj zog thiab sib npaug. Cov Kev Cuam Tshuam Cov Khaub Ncaws Yuav Tsum Muaj Txawv Tebchaws: Q420B xav kom muaj ntau dua lossis sib npaug nrog ntau dua lossis sib npaug rau ntau dua lossis sib npaug rau 27 j at -40 degree. Cov txiaj ntsig lub zog sib txawv (tawm lub zog / tensile lub zog) ntawm Q420 steel yeeb nkab yog feem ntau tsawg dua los yog sib npaug nrog txaus yas deformation muaj peev xwm nyob hauv kev thauj khoom. Tsis tas li ntawd, nws ua rau cov khoom txias zoo tshaj plaws, ntsib qhov kev xav tau ntawm cov txheej txheem fabrication.
Q3: Dab tsi yog qhov sib txawv tseem ceeb ntawm Q420 thiab Q390 yeeb nkab hlau?
Q420 muaj lub zog ntau dua rau lub zog (ntau dua lossis sib npaug li ntawm 420 MPa) dua li 390 MPa), ua rau nws muaj kev tsim nyog nrog cov qauv thauj khoom nrog cov khoom siv siab dua. Q420 muaj cov ntsiab lus ntau dua (xws li NB thiab V), Thaum Q390 feem ntau tsuas muaj manganese (mn) raws li kev sib dhos ua ntej. Q420 muaj kev cuam tshuam ntau dua cov kev cuam tshuam nyuaj, thiab Q420D / e, tshwj xeeb, muaj kev ua tau zoo tshaj qhov piv rau Q390D / e. Q420 yog tus nqi 10% mus rau 15% siab dua Q390 vim yog cov nqi siab dua thiab kev ua. Hauv cov ntawv thov, Q420 feem ntau siv hauv cov tshuab hnyav, ntev ntev cov cuab yeej, thiab cov tsev nce siab, qhov twg siab dua lub zog yog qhov yuav tsum tau ua.
Q4: Qhov ntsuas kub yog dab tsi rau Q420 cov yeeb nkab steel?
Q420B is suitable for ambient temperatures, Q420D for temperatures as low as -20°C, and Q420E for extreme temperatures as low as -40°C. At high temperatures (>350 Qib), lub zog ntawm Q420 maj txo qis, thiab cov hlau kub-resistant xws li muaj kev sib dhos. Qhov tsawg-qhov kub-ua tau zoo ntawm Q420D / e yog zoo dua rau cov roj carbon hlau (xws li QU235b), tab sis xws li 09mnnidr). Yog li ntawd, thaum siv cov cheeb tsam txias, nws cov kev cuam tshuam nyuaj yuav tsum raug tshuaj xyuas kom ntseeg tau tias nws raws li cov cai tsim.
Q5: Cov khoom xa tuaj dab tsi rau Q420 cov yeeb nkab?
Q420 steel pipe is typically delivered in the hot-rolled (HR) or normalized (N) condition, depending on the grade and intended use. Q420B can be delivered in the hot-rolled condition, while Q420D/E typically requires normalizing to ensure low-temperature toughness. The normalizing temperature is generally 880-920°C, with a holding time calculated based on the wall thickness (1.5 minutes/mm). For thick-walled pipe (>40mm), ib qho kev ua txhaum thiab tempering (quenching + txheej txheem (quenching + txheej txheem yuav tsum tau txhim kho kev ua tau zoo. Cov ntaub ntawv kev kho cua sov thiab cov khoom siv ua tshuab khoom siv yuav tsum tau raws li cov zaub mov xa tuaj.
