Ntau npaum li cas cov carbon cov ntsiab lus cuam tshuam rau weldability ntawm Q345 hlau?
Cov pa roj carbon (c) yog qhov tseem ceeb sib txuam cuam tshuam rau lub weldability ntawm Q345 hlau. Nws cov ntsiab lus ncaj qha rau kev txiav txim siab tawg, sib koom ua ke nyuaj, thiab cov txheej txheem nyuaj thaum lub sij hawm sib tw, nrog MN, P, thiab S). Tshwj xeeb, kev cuam tshuam ntawm cov ntsiab lus cardability ntawm Q345 hlau yog feem ntau ntawm peb cov ntsiab lus carbon tseem ceeb, ntau tshaj tawm cov kev cuam tshuam tsis zoo):
1. Cov ntsiab lus carbon yog qhov sib txheeb zoo nrog kev pheej hmoo ntawm weld txias tawg
Txias tawg (kab nrib pleb uas tshwm sim thaum lub sij hawm txias tom qab vuam, feem ntau tshwm sim kom tsis txhob muaj nyob rau hauv Q345 Vuam, thiab Carbon yog thawj qhov ua rau muaj khaub thuas txias:
Kev nyuaj siab zoo: qhov ntau dua cov ntsiab lus carbon, qhov ntau dua cov hlau ua haujlwm tsis muaj zog. Thaum lub sij hawm vuam, qhov cua sov - beurity dependation ua raws li los ntawm kev kub ntxhov sai, nrog lub hardness yooj yim tshaj 350 hv). Qhov no ua rau tus ntse txo qis hauv kev nruj nyob hauv thaj chaw no, thiab tuaj yeem cuam tshuam ncaj qha vim tias seem weld ntxhov siab.
Piv txwv li, yog tias cov pa roj carbon monuts ntawm Q345 nce ntawm 0.16% rau 0.20% rau 0.20% (ze rau cov qauv kev pheej hmoo ntau dua 30%, nce kev pheej hmoo ntawm kev tawg txias los ntawm 2-3 zaug.
Hydrogen-induced cracking: Carbon combines with diffusible hydrogen in the weld to form gases such as CH₄, which accumulate at the grain boundaries between the weld metal and the HAZ. When the hydrogen concentration exceeds a critical value (typically >5 ml / 100 g), nws reacts nrog residual kev nyuaj siab ua rau cov kab nrib pleb. Qhov ntau dua cov ntsiab lus carbon, qhov muaj zog dua cov nyhuv hydrogen "cuab yeej" thiab ntau dua qhov tawg nrawm. Yog li ntawd, GB / T 1591 {{{{{{} nkauj nruj me ntsis uas cov pa roj carbon monoxide ntawm Q345 yuav tsum tau tsawg dua lossis sib npaug tsawg dua lossis sib npaug lossis sib luag rau 60 hli). Qhov tseem ceeb, lub hom phiaj no ua kom txoj kev pheej hmoo ntawm kev tawg txias tsis pub dhau ib qho kev tswj hwm tau los ntawm kev tswj cov pa roj carbon. Yog tias cov ntsiab lus carbon ntau dua 0.20%, txawm nrog preheating (150-250 degree) thiab tom qab cua sov (250 degree), tawg yog qhov nyuaj kom tsis txhob kiag li kev zam.
Ii. Cov ntsiab lus ntawm cov pa roj carbon cov ntsiab lus ntau txo cov tawv ntawm welded pob qij txha.
Cov ntsiab lus yuav tsum tau ua rau Q345 vuam yog "sib phim cov khoom sib tw nrog lub hauv paus hlau" (thiab cov ntsiab lus carbon monoxide yog qhov tseem ceeb rau kev cuam tshuam cov nyiaj no:
Weld metal toughness: During welding, carbon in the wire/electrode transfers to the molten pool. If the base metal carbon content is too high (e.g., >0.18%), Feld hlau sib npaug (CEQ) yuav tshaj tus qauv, ua rau muaj kev tsim ntawm Weld Micruction thiab Txo Lub Zog Hluav Taws Xob (AKV). Cov ntaub ntawv ntsuas qhia tau hais tias thaum cov ntsiab lus carbon ntawm Q345 hauv paus kev lag luam ntawm 50 xyoos (hauv qab cov qauv kev nyab xeeb.
Thaum tshav kub kub -} Cov qauv hluav taws xob zoo li cov khoom siv roj ntsha ua rau muaj kev loj hlob ntawm qhov chaw 30%}} 50% qis dua li ntawm cov hlau. Piv txwv li, tom qab vuam Q345 nrog cov ntsiab lus carbon ntawm 0.20%, lub haz's Axt tus nqi ntawm -40 Qib yuav tsawg dua 20J, tsis ua raws li cov kev xav tau rau E-qib steel.
3. Cov ntsiab lus carbon. Cov ntsiab lus carbon txiav txim siab vuam txheej txheem sib luag
Qhov ntau dua cov ntsiab lus carbon, tus stricter cov txheej txheem tswj cov txheej txheem tsim nyog rau Q345 vuam, uas ncaj qha rau qhov nyuaj thiab tus nqi ntawm cov txheej txheem:
Preheating kub: Q345 nrog cov ntsiab lus carbon ntawm 0.14% {{{}} Yog tias cov ntsiab lus carbon cov ntsiab lus nce mus rau 0.18% -0.20%, txawm tias muaj 12 hli tuab rau siab tshaj 150 nyob rau hauv qis-ib puag ncig) kom tsis txhob tawg.
Heat Input Control: When welding high-carbon Q345 (>0.18%), cov tswv yim tshav kub (vuam tam sim no voltage / ceev) yuav tsum nruj me ntsis txwv rau 15}}} 30 kj / cm. Cov kev tawm hws ntau dhau yuav ua rau coarse haz lis, thaum muaj kev tawm dag zog dhau yuav ua rau muaj kev txias sai sai, uas tuaj yeem ua rau martensite tsim. Rau cov roj carbon Q345 (<0.16%), the heat input range can be expanded to 10-40 kJ/cm, offering greater process adaptability.
Tshaj tawm - Weld Kev Kho Mob: Siab}} Carbon Q345 yuav tsum yov 600 {650 degree) tom qab vuam. Txwv tsis pub, residual kev ntxhov siab thiab cov qauv tawv muaj peev xwm sib txuas los ua ke los ua kom muaj kev sib tsoo qeeb. Txawm li cas los xij, rau cov roj carbon Q345 (piv txwv li, 0.14%), cov kauj ruam no tuaj yeem raug rho tawm thaum vuam nyias daim hlau, txuag sijhawm. Ntsiab lus: Qhov cuam tshuam ntawm cov ntsiab lus carbon rau Q345 Weldability
Cov ntsiab lus carbon yog qhov tseem ceeb tswj tau hauv Q345 Weldability, thiab nws cov kev cuam tshuam tuaj yeem siv ib qho "tseem ceeb qhib":
Muaj ntau ntau (C Tsawg dua lossis sib npaug ntawm 0.16%): Kev pheej hmoo ntawm Veldability zoo, tsis tas yuav tsum muaj cov txheej txheem preheating> 90%;
Risk Range (0.16% < C<=0.20%): Moderate weldability, requiring strict control of preheating temperature, heat input, and hydrogen content, with joint toughness compliance dropping to 70%-80%;
Danger Range (C > 0.20%): Extremely poor weldability, with significant cold cracking and insufficient toughness. Even with specialized processes, joint reliability is difficult to guarantee, and the weld does not meet Q345 standard requirements. Therefore, in actual welding, Q345 with a lower carbon content (such as C=0.14%-0.16% marked in the material list) should be given priority. Especially for low-temperature environments (below -20°C) or thick plate (>20mm) qauv, qhov sib txawv me me hauv cov ntsiab lus carbon (xws li 0.02%) yuav txiav txim siab ncaj qha rau kev ua tiav lossis tsis ua haujlwm vuam.