Preheating thiab post-weld heat treatment (PWHT) ncaj qha cuam tshuam rau Q235NH Corten Steel's weld joint zoo-lawv tiv thaiv cov kab mob khaub thuas, txo qis kev ntxhov siab, thiab khaws lub hauv paus hlau lub toughness thiab corrosion kuj. Rau cov neeg tsim khoom, cov lus nug tseem ceeb yog: Q235NH puas xav tau cov kev kho mob no thaum vuam? Raws li GB / T 4171 tus qauv, kev siv vuam, thiab cov khoom siv, cov ntsiab lus tseem ceeb yog qhov tseeb:Q235NH tsis xav tau preheating los yog PWHT rau nyias daim hlau nyob rau hauv ib puag ncig me me, tab sis preheating yog yuav tsum tau rau cov phaj tuab los yog txias txias; PWHT tsuas yog xav tau rau qhov hnyav tshwj xeeb - cov xwm txheej ua haujlwm. Hauv qab no yog ib qho yooj yim, kev txiav txim siab tawg.
Cov ntsiab lus tseem ceeb: Vim li cas Kev Kho Kub Kub Teebmeem rau Vuam
Vuam Q235NH suav nrog cov cua kub hauv zos, uas ua rau qhov kub thiab txias gradients thiab residual stress. Kev kho cua sov hais txog ob qhov kev pheej hmoo tseem ceeb:
Preheating: Txo qhov cua txias ntawm thaj chaw vuam, zam qhov tsim ntawm cov tawv tawv, brittle microstructures thiab cov kab nrib pleb txias (ua los ntawm hydrogen tsub zuj zuj thiab txias ceev).
PWHT: Relieves residual stress, softens overly hard weld metal, and improves the weld joint's ductility-txawm tias nws tsis tshua xav tau rau Q235NH vim nws cov ntsiab lus carbon tsawg.
Preheating Requirements: Los ntawm Thickness & Ib puag ncig
Preheating rau Q235NH yog txiav txim siab los ntawm phaj thickness thiab ambient kub, nrog rau qhov tseeb qhov yuav tsum tau:
Tsis xav tau preheating: Phaj Tsawg dua los yog sib npaug li 16 hli tuab, welded nyob rau hauv ambient kub Ntau tshaj los yog sib npaug rau 15℃. Cov ntoo khaub lig nyias -section tso cai rau kom txias txias, thiab qis hydrogen consumables (xws li, E4315) ntxiv tshem tawm qhov mob khaub thuas tawg.
Yuav tsum Preheating: Plates 16-50mm thick, or any thickness welded at ambient temperatures ≤10℃. Preheat to 80-120℃ to slow cooling; for plates >50mm (kev cai tuab daim hlau), nce preheat kub rau 120-150 degree.
Txoj kev Preheating: Siv hluav taws xob tiv thaiv cua sov lossis roj cua sov, ua kom tag nrho thaj chaw vuam (tsawg kawg 3 zaug ntawm lub phaj tuab) ncav cuag lub hom phiaj kub ua ntej vuam.
Tshaj tawm -Kev Kho Hniav Kub: Thaum Yuav Tsum Tau?
Q235NH cov ntsiab lus qis qis (tsawg dua lossis sib npaug rau 0.18%) thiab cov khoom siv zoo txhais tau tias PWHT tsis yog tus qauv yuav tsum tau ua. Nws tsuas yog tsim nyog hauv ob qhov xwm txheej tshwj xeeb:
Thick Plates >50 hli: Tom qab vuam, ua kom muaj kev ntxhov siab annealing ntawm 550-600℃(tuav rau 1-2 teev ntawm 25mm thickness) kom tshem tawm cov kev ntxhov siab seem thiab tsis txhob lamellar tearing.
Critical Low-Cov ntawv thov kub: Yog hais tias Q235NH yog marginally siv ntawm -20℃rau load- bearing Cheebtsam, PWHT (550-580 degree) softens lub weld tshav kub-cuam tshuam cheeb tsam (HAZ) thiab txhim kho toughness.
Nco tseg: Tsis txhob overheating (＞650 degree) thaum lub sij hawm PWHT, vim nws coarsens grain qauv thiab txo corrosion kuj.
Vuam txheej txheem & Kev kho cua sov Compatibility
Cov txheej txheem vuam sib txawv cuam tshuam rau cov khoom siv hluav taws xob thiab cov cua txias, kho cov kev kho cua sov xav tau:
SMAW (Welding): Siv cov khoom siv hluav taws xob tsawg (E4315) kom txo tau cov cua sov ua ntej- cov phaj 16-20mm yuav hla preheating hauv qhov chaw sov.
GMAW (MIG Welding): Cov khoom siv hluav taws xob ntau dua li SMAW; rau daim hlau Tsawg dua los yog sib npaug li 20mm, tsis xav tau preheating txawm nyob ntawm 5-10 degree.
FCAW (Flux{0}}Cored Vuam): Self-shielded wires have moderate hydrogen content; preheat plates >16mm txog 80℃kom muaj kev nyab xeeb.
Tswv yim tswv yim & Common yuam kev
Kev ntsuas kub: Siv lub ntsuas kub tiv tauj los xyuas qhov ntsuas kub ua ntej-xav tias ua haujlwm yuav ua rau muaj cua sov tsis txaus lossis ntau dhau.
Tsis txhob dhau -Preheating: Preheating saum 150℃rau nyias daim hlau ua rau cov qoob loo loj hlob ntau dhau, txo qhov sib koom ua ke toughness.
Hla qhov tsis tsim nyog PWHT: Standard daim ntaub ntawv (phaj Tsawg dua los yog sib npaug rau 50mm, ib puag ncig me me) tsis xav tau PWHT, vim nws nkim sij hawm thiab yuav degrade nto patina tsim.
Hauv cov ntsiab lus, Q235NH qhov kev kho cua sov xav tau yog qhov xwm txheej- nyob ntawm: preheating yog khi rau phaj thickness thiab ambient kub, thaum PWHT tsuas yog rau cov tuab lossis cov khoom tseem ceeb. Ua raws li cov lus qhia no ua kom cov pob qij txha tuav tau Q235NH qhov toughness thiab corrosion tsis kam, zam kev tsis tsim nyog thiab nqi.
