20 # seamless steel yeeb nkab yog cov khoom qib uas tau teev tseg hauv GB3087-2008 "Seamless steel kav rau qis thiab nruab nrab siab boilers". Nws yog qhov zoo tshaj plaws carbon structural steel seamless steel yeeb nkab haum rau kev tsim ntau yam tsawg-siab thiab nruab nrab-siab boilers. Nws yog cov khoom siv ntau thiab loj-ntev steel yeeb nkab. Thaum lub chaw tsim khoom ntawm cov khoom siv boiler tau tsim qhov kub thiab txias reheater header, nws tau pom tias muaj qhov cuam tshuam loj heev ntawm cov kab nrib pleb ntawm sab hauv ntawm ntau lub yeeb nkab txuas. Cov khoom siv yeeb nkab yog 20 steel nrog qhov tshwj xeeb ntawm Φ57mm × 5mm. Peb tau tshuaj xyuas cov yeeb nkab steel tawg thiab ua ib qho kev ntsuam xyuas kom rov tsim dua qhov tsis xws luag thiab nrhiav kom paub qhov ua rau ntawm qhov sib tsoo tawg.

1. Txhaum feature tsom xam
Crack morphology: Nws tuaj yeem pom tau tias muaj ntau qhov sib txawv ntawm cov kab nrib pleb faib raws qhov ntev ntawm cov yeeb nkab steel. Cov kab nrib pleb yog teem kom zoo. Txhua qhov tawg muaj ib tug wavy feature, nrog ib tug me ntsis deflection nyob rau hauv lub longitudinal kev taw qhia thiab tsis muaj longitudinal khawb. Muaj qee qhov deflection lub kaum sab xis ntawm qhov tawg thiab qhov chaw ntawm cov yeeb nkab steel thiab ib qho dav. Muaj oxides thiab decarburization ntawm ntug ntawm qhov tawg. Hauv qab yog blunt thiab tsis muaj lub cim ntawm kev nthuav dav. Cov qauv matrix yog ib txwm ferrite + pearlite, uas tau muab faib rau hauv ib lub band thiab muaj ib qho loj ntawm 8. Qhov ua rau ntawm qhov tawg yog cuam tshuam nrog kev sib txhuam ntawm cov phab ntsa hauv cov yeeb nkab steel thiab cov pwm puab thaum lub sij hawm tsim cov cev steel.

Raws li macroscopic thiab microscopic morphological yam ntxwv ntawm cov kab nrib pleb, nws tuaj yeem suav tau tias qhov tawg tau tsim ua ntej kev kho cua sov kawg ntawm cov yeeb nkab steel. Cov yeeb nkab steel siv Φ90mm round tube billet. Cov txheej txheem tseem ceeb uas nws dhau mus yog kub perforation, kub dov thiab txoj kab uas hla txo, thiab ob daim duab txias. Cov txheej txheem tshwj xeeb yog tias Φ90mm round tube billet yog dov rau hauv Φ93mm × 5.8mm ntxhib raj, thiab ces kub dov thiab txo rau Φ72mm × 6.2mm. Tom qab pickling thiab lubrication, thawj daim duab txias yog nqa tawm. Qhov tshwj xeeb tom qab kos duab txias yog Φ65mm × 5.5mm. Tom qab nruab nrab annealing, pickling, thiab lubrication, qhov thib ob txias yog nqa tawm. Qhov tshwj xeeb tom qab kos duab txias yog Φ57mm × 5mm.

Raws li kev txheeb xyuas cov txheej txheem tsim khoom, cov yam ntxwv cuam tshuam rau kev sib txhuam ntawm cov phab ntsa hauv cov yeeb nkab steel thiab cov tuag sab hauv feem ntau yog qhov zoo ntawm lubrication thiab kuj muaj feem xyuam rau cov yas ntawm cov yeeb nkab steel. Yog hais tias cov yas ntawm cov yeeb nkab steel tsis zoo, qhov ua tau ntawm kev kos cov kab nrib pleb yuav nce ntau, thiab cov yas tsis zoo yog cuam tshuam nrog kev ntxhov siab nruab nrab ntawm kev kho cua sov. Raws li qhov no, nws yog inferred tias cov kab nrib pleb tuaj yeem tsim nyob rau hauv cov txheej txheem kos duab txias. Tsis tas li ntawd, vim tias cov kab nrib pleb tsis qhib rau qhov loj thiab tsis muaj qhov pom tseeb ntawm kev nthuav dav, nws txhais tau hais tias cov kab nrib pleb tsis tau ntsib kev cuam tshuam ntawm cov duab kos duab deformation tom qab lawv tsim, yog li nws yog ntxiv inferred tias feem ntau yuav. lub sij hawm rau cov kab nrib pleb yuav tsum yog qhov thib ob txias txheej txheem. Cov feem cuam tshuam feem ntau yog cov roj lubrication tsis zoo thiab / lossis kev ntxhov siab tsis zoo annealing.

Txhawm rau txiav txim siab qhov ua rau ntawm cov kab nrib pleb, kev kuaj kev tsim tawm tawg tau ua tiav hauv kev koom tes nrog cov tuam txhab steel yeeb nkab. Raws li kev soj ntsuam saum toj no, cov kev ntsuam xyuas hauv qab no tau ua tiav: Nyob rau hauv cov xwm txheej uas qhov perforation thiab kub dov txoj kab uas hla txo cov txheej txheem tseem tsis hloov, lub lubrication thiab / los yog kev ntxhov siab nyem annealing tshav kub kho cov xwm txheej raug hloov, thiab cov kav hlau rub tau raug tshuaj xyuas. sim rov tsim dua qhov tsis xws luag.

2. Kev npaj xeem
Cuaj qhov kev sim no tau npaj los ntawm kev hloov cov txheej txheem lubrication thiab cov txheej txheem annealing. Ntawm lawv, phosphating thiab lubrication lub sij hawm yuav tsum yog 40min, ib txwm intermediate kev nyuaj siab nyem annealing kub yuav tsum tau yog 830 ℃, thiab ib txwm rwb thaiv tsev lub sij hawm yuav tsum yog 20min. Cov txheej txheem xeem siv 30t txias chav tsev thiab cov menyuam hauv qab cua sov kho rauv.

3. Cov ntawv xeem
Los ntawm kev tshuaj xyuas cov kav hlau uas tsim los ntawm 9 lub tswv yim saum toj no, nws tau pom tias tsuas yog cov phiaj xwm 3, 4, 5, thiab 6, lwm cov tswv yim txhua tus tau co los yog hloov pauv mus rau qhov sib txawv. Ntawm lawv, scheme 1 muaj ib qho annular kauj ruam; schemes 2 thiab 8 muaj transverse kab nrib pleb, thiab cov tawg morphology zoo ib yam li uas pom nyob rau hauv ntau lawm; schemes 7 thiab 9 tau shaken, tab sis tsis pom transverse tawg.

4. Kev tshuaj xyuas thiab kev sib tham
Los ntawm kev sim ntau, nws tau lees paub tag nrho tias lubrication thiab nruab nrab kev ntxhov siab nyem annealing thaum lub caij txias txheej txheem ntawm cov kav hlau steel muaj qhov cuam tshuam tseem ceeb rau qhov zoo ntawm cov kav hlau tiav. Tshwj xeeb, schemes 2 thiab 8 rov tsim dua qhov tsis xws luag ntawm cov phab ntsa sab hauv ntawm cov yeeb nkab steel uas pom hauv cov khoom saum toj no.

Scheme 1 yog los ua thawj qhov kev kos duab txias rau ntawm qhov kub-dov txo qis-inch niam raj yam tsis ua cov txheej txheem phosphating thiab lubrication. Vim tsis muaj lubrication, lub load yuav tsum tau thaum lub sij hawm txias txias txheej txheem tau mus txog lub siab tshaj plaws load ntawm lub txias drawing tshuab. Cov txheej txheem kos duab txias yog ua haujlwm hnyav heev. Kev co ntawm cov yeeb nkab steel thiab kev sib txhuam nrog cov pwm ua rau pom tseeb cov kauj ruam ntawm cov phab ntsa sab hauv ntawm lub raj, qhia tau hais tias thaum lub plasticity ntawm niam lub raj yog zoo, txawm hais tias lub unlubricated daim duab muaj qhov cuam tshuam tsis zoo, nws tsis yooj yim los ua. cov kab nrib pleb. Nyob rau hauv lub tswv yim 2, cov yeeb nkab steel uas tsis zoo phosphating thiab lubrication yog txuas ntxiv txias tsis muaj kev ntxhov siab rau nruab nrab annealing, uas ua rau cov kab nrib pleb zoo sib xws. Txawm li cas los xij, nyob rau hauv Scheme 3, tsis muaj qhov tsis xws luag nyob rau hauv qhov nruam txias ntawm cov yeeb nkab steel nrog zoo phosphating thiab lubrication yam tsis muaj kev ntxhov siab hauv nruab nrab annealing, uas ua ntej qhia tau hais tias tsis zoo lubrication yog lub ntsiab ntawm cov kab nrib pleb. Schemes 4 mus rau 6 yog los hloov cov txheej txheem kev kho cua sov thaum ua kom lub lubrication zoo, thiab tsis muaj qhov tsis xws luag tshwm sim, qhia tias qhov nruab nrab ntawm kev ntxhov siab annealing tsis yog qhov tseem ceeb ua rau muaj qhov tshwm sim ntawm cov kab nrib pleb. Schemes 7 mus rau 9 hloov cov txheej txheem kho cua sov thaum lub sij hawm luv luv phosphating thiab lubrication los ntawm ib nrab. Yog li ntawd, cov kav hlau steel ntawm Schemes 7 thiab 9 muaj co kab, thiab Scheme 8 tsim cov kab nrib pleb zoo sib xws.

Cov kev sib piv saum toj no qhia tau hais tias cov kab nrib pleb yuav tshwm sim nyob rau hauv ob qho tib si ntawm lubrication tsis zoo + tsis muaj qhov nruab nrab annealing thiab lubrication tsis zoo + qis nruab nrab annealing kub. Nyob rau hauv cov ntaub ntawv ntawm lubrication tsis zoo + zoo intermediate annealing, zoo lubrication + tsis intermediate annealing, thiab zoo lubrication + tsawg intermediate annealing kub, txawm tias co kab defects yuav tshwm sim, transverse tawg yuav tsis tshwm sim nyob rau hauv lub puab phab ntsa ntawm cov yeeb nkab steel. Cov roj lubrication tsis zoo yog qhov ua rau muaj kev cuam tshuam ntawm cov kab nrib pleb, thiab kev ntxhov siab nruab nrab tsis zoo yog qhov ua rau muaj kev cuam tshuam.

Txij li thaum qhov kev nyuab siab ntawm cov yeeb nkab steel yog proportional rau qhov kev sib txhuam quab yuam, lubrication tsis zoo yuav ua rau muaj kev nce ntxiv hauv cov duab kos thiab txo tus nqi kos duab. Qhov ceev yog tsawg thaum cov yeeb nkab steel yog thawj kos. Yog hais tias qhov ceev yog qis dua ib qho nqi, uas yog, nws mus txog qhov taw tes bifurcation, lub mandrel yuav ua rau nws tus kheej zoo siab vibration, uas ua rau co kab. Nyob rau hauv cov ntaub ntawv ntawm lubrication tsis txaus, axial kev sib txhuam ntawm qhov chaw (tshwj xeeb tshaj yog nyob rau hauv lub puab nto) hlau thiab tuag thaum lub sij hawm kos duab yog zoo heev, uas ua rau ua hauj lwm hardening. Yog tias qhov kev ntxhov siab tom qab annealing kub kho qhov kub ntawm cov yeeb nkab steel tsis txaus (xws li txog 630 ℃ teem rau hauv qhov kev sim) los yog tsis muaj annealing, nws yog ib qho yooj yim ua rau tawg tawg.

Raws li theoretical xam (qhov qis tshaj recrystallization kub ≈ 0.4 × 1350 ℃), recrystallization kub ntawm 20 # steel yog hais txog 610 ℃. Yog hais tias qhov kub thiab txias yog nyob ze rau qhov kub ntawm recrystallization, cov yeeb nkab steel tsis ua kom tiav recrystallize, thiab kev ua hauj lwm hardening tsis raug tshem tawm, ua rau cov khoom tsis zoo plasticity, hlau ntws yog thaiv thaum muaj kev sib txhuam, thiab sab hauv thiab sab nrauv ntawm cov hlau yog hnyav heev. deformed unevenly, yog li tsim ib tug loj axial ntxiv kev nyuaj siab. Yog li ntawd, axial kev ntxhov siab ntawm cov hlau sab hauv ntawm cov yeeb nkab steel tshaj nws qhov kev txwv, yog li tsim cov kab nrib pleb.

5. Cov lus xaus
Lub cim ntawm cov kab nrib pleb ntawm cov phab ntsa sab hauv ntawm 20 # seamless steel yeeb nkab yog tshwm sim los ntawm kev sib xyaw ua ke ntawm cov roj lubrication tsis zoo thaum lub sij hawm kos duab thiab tsis muaj kev ntxhov siab nruab nrab tsis txaus annealing kev kho cua sov (lossis tsis muaj annealing). Ntawm lawv, lubrication tsis zoo yog qhov laj thawj tseem ceeb, thiab kev ntxhov siab nruab nrab ntawm kev ntxhov siab tsis zoo annealing (lossis tsis muaj annealing) yog qhov ua rau muaj kev cuam tshuam. Txhawm rau kom tsis txhob muaj qhov tsis zoo sib xws, cov tuam txhab tsim khoom yuav tsum xav kom cov neeg ua haujlwm hauv kev cob qhia nruj me ntsis ua raws li cov kev cai ntawm cov txheej txheem lubrication thiab kev kho cua sov hauv kev tsim khoom. Tsis tas li ntawd, txij li cov menyuam-hauv qab nruam annealing rauv yog lub tshuab hluav taws xob txuas ntxiv, txawm hais tias nws yooj yim thiab nrawm rau thauj khoom thiab tshem tawm, nws nyuaj rau tswj qhov kub thiab ceev ntawm cov khoom sib txawv thiab qhov ntau thiab tsawg hauv qhov cub. Yog tias nws tsis nruj me ntsis raws li cov kev cai, nws yog ib qho yooj yim uas yuav ua rau tsis sib xws annealing kub los yog luv luv lub sij hawm, uas ua rau recrystallization tsis txaus, ua rau muaj teeb meem nyob rau hauv cov khoom tom ntej. Yog li ntawd, cov tuam txhab lag luam uas siv cov yob-hauv qab txuas ntxiv rau qhov cua sov rau kev kho cua sov yuav tsum tswj hwm ntau yam kev xav tau thiab kev ua haujlwm tiag tiag ntawm kev kho cua sov.