1.Yuav ua li cas yog grain loj? Dab tsi yog qhov loj npaum li cas ntawm cov ntawv txias -rolled steel ntawv?
Grain size yog hais txog qhov loj ntawm tus kheej cov pob zeb me me (grains) nyob rau hauv cov qauv polycrystalline ntawm cov hlau. Nws yog feem ntau qhia raws li qhov nruab nrab ntawm cov nplej loj thiab tuaj yeem pom tau siv lub tshuab ntsuas metallographic thiab ntsuas raws li cov qauv xws li ASTM E112.
Rau txias- dov coils (tshwj xeeb tshaj yog cov khoom lag luam annealed), cov qoob loo loj yog kwv yees li hauv qab no:
Common Grain Size: Feem ntau cov khoom lag luam muaj txias- cov ntawv yob muaj cov ntawv loj ntawm ASTM qib 7 thiab 10. Hloov mus rau qhov nruab nrab txoj kab uas hla, qhov no yog kwv yees li 30 micrometers (0.030 mm) txog 10 micrometers (0.010 mm).
Ultra-Zoo Grain: Qee lub siab- steels muaj zog, los ntawm microalloying thiab tswj dov thiab txias, tuaj yeem muaj cov nplej ua kom zoo rau ASTM qib 12 lossis siab dua (< 5 micrometers).
Coarse Grain: If the annealing temperature is too high or the annealing time is too long, the grains can grow to below ASTM grade 5 (>60 micrometers), qhov xwm txheej uas feem ntau zam hauv kev tsim khoom.
2.Yuav ua li cas cov nplej loj muaj nyob rau saum npoo zoo thaum lub sij hawm stamping?
Tsim Mechanism: Thaum cov nplej loj loj, cov anisotropy ntawm txhua lub lis piam (qhov sib txawv deformation muaj peev xwm nyob rau hauv cov lus qhia sib txawv) ua qhov tseem ceeb. Thaum lub sij hawm stamping, lub macroscopic uniform deformation yog qhov tshwm sim ntawm kev sib koom tes deformation ntawm suav tsis txheeb nplej. Yog hais tias cov nplej yog ntxhib dhau lawm, cov nplej uas koom nrog deformation kuj tsawg, thiab tus cwj pwm deformation ntawm txhua cov nplej yuav cuam tshuam rau ntawm qhov chaw macroscopic.
Qhov tshwm sim: Nyob rau hauv kev ntxhov siab, cov nplej nrog cov kev taw qhia sib txawv muaj qhov sib txawv ntawm qhov sib txawv, ua rau cov kab mob tsis sib xws ntawm qhov chaw, hu ua txiv kab ntxwv tev nyhuv. Qhov no tsis tsuas yog cuam tshuam rau qhov zoo nkauj tab sis kuj tseem pom tom qab pleev xim, thiab hauv cov xwm txheej hnyav, tuaj yeem dhau los ua cov ntsiab lus kev ntxhov siab, ua rau tawg.
Cov Lus Qhia dav dav: Rau lub tsheb sab nrauv lub cev vaj huam sib luag (xws li lub qhov rooj thiab lub hood) nrog cov kev xav tau zoo heev ntawm qhov chaw, qhov loj ntawm cov nplej feem ntau yuav tsum yog me me, feem ntau tswj tau rau qib ASTM 7-8 lossis finer.
3.Dab tsi yog qhov cuam tshuam ntawm cov hmoov nplej ntau dhau los yog ntxhib ntawm lub zog thiab plasticity (elongation) ntawm cov khoom?
Cov nplej zoo heev (xws li ASTM qib 12 thiab siab dua):
Lub zog (↑): Ntau cov qoob loo loj heev cuam tshuam kev txav mus los, ua rau muaj zog ntau ntxiv thiab lub zog tensile.
Plasticity (↓): Txawm hais tias cov nplej zoo tuaj yeem txhim kho lub zog thiab tawv, cov nplej zoo heev ua rau kev ua haujlwm hnyav heev. Thaum lub sij hawm molding, cov ntaub ntawv pov thawj siab tsis kam mus deformation, yooj yim ua rau pwm hnav thiab hnyav springback, ua rau nws nyuaj rau cov duab. Rau qhov chaw uas yuav tsum tau ua kom yooj yim molding, cov nplej zoo heev yog qhov ua rau muaj kev puas tsuaj.
Cov qoob loo nruab nrab (piv txwv li, ASTM qib 7-9):
Qhov zoo tshaj plaws tshuav nyiaj li cas: Muaj lub zog txaus los tiv thaiv kev deformation thaum siv, nrog rau cov yas zoo (elongation) thiab qhov qis qis qis, ua kom yooj yim stamping.
Cov nplej ntau dhau (piv txwv li, ASTM qib 5 thiab hauv qab):
Lub zog (↓): Cov ciam teb tsawg dua txo qhov kev tawm tsam rau kev txav mus los, ua rau cov khoom siv softer (yield zog qis).
Plasticity (↓): Txawm hais tias qhov elongation yuav tsis qis ntawm lub tensile nkhaus, lub peev xwm deform hauv zos tsis zoo. Thaum ntxhib- cov ntaub ntawv nplej tau raug kev nyuaj siab, deformation zoo li mloog zoo rau ob peb cov mos mos- taw qhia cov nplej, ua rau lub caj dab thaum ntxov thiab tawg, piv txwv li, txo qis hauv cov elongation.
4.Rau qhov sib sib zog nqus nqus (xws li kev tsim cov kaus poom dej haus thiab lub tsheb roj lauj kaub), puas muaj cov kev cai tshwj xeeb rau cov nplej loj?
Yam Yuav Tsum Tau Paub Txog: Sib sib zog nqus- kos steels (xws li IF steel, interstitial steel) feem ntau yuav tsum tau coarsened nplej kom tsim nyog (tab sis tsis txhob ntxhib li los ua cov nyhuv txiv kab ntxwv). Piv txwv li, qhov loj ntawm cov nplej ntxiv ntawm - sib sib zog nqus - kos txias - cov ntawv dov feem ntau yog tswj tau nyob ib ncig ntawm ASTM qib 6-7. Qhov no yog vim qhov tsim nyog coarser nplej muab cov yas zoo dua, qis zog tawm los, thiab muaj txiaj ntsig zoo rau cov khoom ntws hauv qhov tuag.
Lub luag haujlwm tseem ceeb ntawm Uniformity: Sib sib zog nqus nqus yog qhov yooj yim tshaj plaws rau cov nplej sib xyaw (piv txwv li, sib xyaw ntawm cov nplej loj thiab me).
Yog tias cov khoom muaj ob qho tib si ASTM qib 5 coarse nplej thiab ASTM qib 9 cov nplej zoo, deformation yuav tsis sib xws. Zoo- cov cheeb tsam cov nplej muaj lub zog siab thiab nyuaj rau deform, thaum ntxhib- cov cheeb tsam cov nplej muaj zog tsawg thiab yooj yim rau deform.
Raws li qhov kev ntxhov siab hnyav ntawm kev sib sib zog nqus nqus, qhov kev tsis sib haum xeeb no yuav sai sai ua rau ntau dhau hauv zos thinning, nws thiaj li ua rau tawg ntawm qhov ntxhib - cov ciam teb lossis hauv cov ntxhib - cov cheeb tsam grained. Yog li ntawd, metallographic tshuaj xyuas qhov sib sib zog nqus-kos txias- cov ntawv dov muaj cov cai nruj heev txog kev hloov pauv ntawm cov nplej.
5.Hauv kev tsim khoom tiag tiag, peb tuaj yeem tau txais cov qoob loo zoo tshaj plaws los ntawm kev tswj cov txheej txheem?
Txias dov txo: Qhov ntau dua qhov txias dov deformation, qhov hnyav dua cov nplej tawg, lub zog khaws cia ntau dua, thiab ntau dua qhov kev tsav tsheb rau recrystallization. Qhov no feem ntau ua rau cov nplej zoo dua tom qab recrystallization. Yog tias qhov kev txo qis tsawg dhau, qhov kev tsav tsheb tsis txaus, uas tuaj yeem yooj yim ua rau kev tsim cov nplej ntxhib.
Annealing kub thiab lub sij hawm (qhov tseem ceeb tshaj plaws):
Tsis tshua muaj kub, lub sij hawm luv luv: Recrystalization nyuam qhuav ua tiav, thiab cov nplej zoo heev.
Kub kub, ntev lub sij hawm: grain loj hlob tshwm sim (grain engulfment mechanism). Txhawm rau kom tau txais cov nplej ntawm ib qho loj me, kev tswj xyuas qhov kub thiab txias thiab tuav lub sij hawm yog yuav tsum tau nyob rau hauv ib tug nruam annealing kab los yog tswb - hom rauv.
Alloying element thiab thib ob -theem hais:
Ntxiv cov ntsiab lus microalloying (xws li Nb, Ti) tsim cov khoom zoo carbonitride uas ua zoo li "nails" anchoring ntawm cov ciam teb, zoo tiv thaiv kev loj hlob ntawm cov nplej. Txawm tias muaj qhov kub thiab txias dua, cov nplej zoo tuaj yeem tau. Qhov no yog lub hauv paus rau kev ua tau zoo -grained siab- lub zog steel.
Rau kev sib sib zog nqus- kos cov hlau, cov precipitates no yuav tsum tau tswj kom tsis txhob muaj kev cuam tshuam ntau dhau ntawm kev loj hlob ntawm cov nplej, thiaj li yuav tau txais cov nplej ntxhib zoo nrog cov qauv zoo.
Leveling (Quenching thiab Tempering): Cov txheej txheem kawg -leveling-thaum lub hom phiaj tseem ceeb ntawm kev txhim kho cov duab thiab tshem tawm cov qoob loo ntawm cov qoob loo, kuj qhia qee qhov me me ntawm qhov tsis sib xws hauv cov nplej, zoo - kho qhov ua tau zoo kawg, tab sis feem ntau tsis hloov pauv cov qoob loo loj.