1.Vim li cas qhov txias txias cuam tshuam qhov hardness ntawm txias-rolled coils? Lub hauv paus ntsiab lus yog dab tsi?
Cov khoom hloov pauv theem sib txawv: Nrog rau qhov txias txias, atoms muaj sijhawm txaus rau diffuse, tsim ferrite thiab pearlite (mos theem); Nrog rau qhov txias txias sai heev, atoms tsis muaj sijhawm txaus rau diffuse, ua rau tsis yog -diffusional theem transformation, tsim martensite (theem nyuaj). Martensite is a supersaturated solid solution with severe lattice distortion and high dislocation density, thus exhibiting extremely high hardness.
Cov carbide morphology txawv: Rau qis- carbon steel, cua txias ceev tiv thaiv cov pa roj carbon atom los ntawm kev sib sau ua ke tag nrho, tsim cov cementite zoo lossis supersaturated cov ntsiab lus, uas muab kev sib zog ua kom muaj zog; qeeb txias ua rau coarse carbides thiab txaus softening.
Cov qoob loo loj: Cov cua txias nrawm inhibits kev loj hlob ntawm cov nplej, ua rau cov nplej nplua nuj (zoo nplej ntxiv dag zog, me ntsis nce hardness); qeeb txias ua rau coarse nplej thiab txo hardness.
2.Rau qhov zoo tib yam qis- carbon steel txias- dov coils (xws li SPCC thiab DC01), qhov cua txias tshwj xeeb cuam tshuam li cas rau qhov hardness?
Slow furnace cooling (tsis tshua muaj cua txias npaum li cas, xws li<30℃/h): This results in coarse ferrite + coarse lamellar pearlite, with large grains. The hardness is lowest at this stage, with HRB typically between 35 and 50 (completely softened).
Cua txias (qhov nruab nrab cua txias): Qhov no ua rau zoo ferrite + nplua lamellar pearlite (sorbite). Vim cov nplej refinement thiab txo pearlite interlamellar qhov sib txawv, qhov hardness nce, muaj peev xwm ncav cuag 55-65 HRB.
Cua txias los yog txau txias txias (kuj ceev ceev): Yog tias qhov txias txias txaus, bainite los yog siab -density dislocation ferrite yuav tsim nyob rau hauv qee qhov chaw, ntxiv rau qhov hardness ntxiv; HRB tuaj yeem tshaj 70.
Kev txias txias heev (quenching): Yog tias dej ncaj qha quenched, martensite yuav tsim, thiab lub hardness yuav nce mus txog HRC 30 (hloov mus rau HRB tsis muaj nuj nqis vim qhov hnyav hnyav).
3.Yuav ua li cas cov cua txias yuav siv los tswj cov hardness ntawm siab -lub zog steel (xws li DP steel) ntawm ib tug nruam annealing ntau lawm kab?
Lub Hom Phiaj: Kom tau txais ob lub-theem microstructure ntawm mos ferrite + hard martensite, ua kom muaj zog tsis muaj zog, siab tensile zog, thiab ua haujlwm zoo.
Txheej Txheem Tswjhwm: Cov ntawv hlau yog rhuab mus rau ob-theem cheeb tsam (kwv yees li 770 ~ 830 degree) nyob rau hauv thaj tsam annealing, qhov taw tes ntawm microstructure yog ferrite + austenite.
Cov kauj ruam tseem ceeb: Kev ua kom txias sai heev (ultra- txias txias) yuav tsum tau ua haujlwm, feem ntau ntau dua 30℃/ s, thiab tseem tshaj 100℃/ s.
Mechanism: Qhov no ceev ceev ceev yog txaus los inhibit qhov kev hloov ntawm austenite rau pearlite los yog bainite, yuam nws mus rau hauv martensite ntawm qhov kub thiab txias.
Cov txiaj ntsig Hardness: Yog tias qhov ntsuas cua txias tsis nrawm txaus, pearlite lossis bainite yuav tsim, ua rau tsis muaj zog tensile thiab hardness nyob rau hauv cov khoom kawg, ua rau nws tsis haum rau dual -theem steel. Yog li ntawd, tus nqi cua txias ncaj qha txiav txim qhov feem ntawm cov theem nyuaj (martensite) thiab qhov kawg hardness hauv DP steel.
4.Ntawm qhov hardness ntau ntxiv, dab tsi lwm yam tsis zoo tuaj yeem ua rau txias txias heev?
Ua kom brittleness: Yog hais tias qhov txias txias yog sai heev, ua rau ntau tshaj martensite tsim, cov khoom yas yuav txo qis, elongation yuav poob, thiab tawg yuav tshwm sim ncaj qha thaum stamping.
Sheet shape defects (wavy/warp): Cov cua txias heev (tshwj xeeb tshaj yog dej quenching lossis haib dav hlau txias) ua rau muaj kev ntxhov siab loj heev nyob rau hauv lub strip. Kev txias tsis sib xws tuaj yeem ua rau muaj teeb meem ntawm daim ntawv nyuaj (xws li ntug waviness, nruab nrab waviness).
Kev pheej hmoo ntawm kev laus: Rau qee cov qib steel, yog tias qhov txias txias tsis ua raws li kev kho mob kom tsim nyog, cov pa roj carbon atoms yaj yuav ua rau lub sijhawm tom qab chav tsev kub cia lossis pleev xim, ua rau muaj zog ntxiv thiab tsis muaj zog (natural aging).
Kev ua haujlwm tsis sib xws: Hauv tswb annealing, tus nqi txias ntawm cov hlau kauj yog nrawm dua ntawm cov npoo thiab qeeb ntawm cov tub ntxhais. Qhov sib txawv ntawm qhov txias txias ncaj qha ua rau qhov tsis sib xws ntawm cov coil (nqus npoo, softer core), cuam tshuam qhov sib xws ntawm kev ua haujlwm tom qab los ntawm tus neeg siv.
5.Hauv kev tsim khoom tiag tiag, peb yuav ua li cas tsim cov txheej txheem txias raws li lub hom phiaj hardness?
Txiav Txim Lub Hom Phiaj Ua Haujlwm: Ua ntej, qhia meej rau cov neeg siv khoom qhov xav tau hardness ntau yam (xws li, xav tau cov khoom muag muag nrog HRB 45-55, lossis cov hlau muaj zog nrog lub zog tensile ntawm 780MPa).
Nug CCT Curve (Nruam Cooling Transition Curve): Rau cov qib steel tshwj xeeb, sab laj rau lawv cov kab nkhaus CCT. Qhov nkhaus no qhia meej cov txheej txheem engineers: ntawm qhov txias npaum li cas, qhov microstructure yuav tau txais, thiab kwv yees hardness.
Xaiv Txoj Kev Txias:
Rau qhov softest (qhov tob tob), xaiv qhov txias txias (piv txwv li, qeeb txias hauv lub tswb nrov lossis cua txias tom qab tuav).
Rau nruab nrab hardness (zoo ib yam stamping), xaiv tswj txias (qhov txias txias seem nyob rau hauv ib tug nruam annealing kab).
Rau lub zog siab (DP steel, MS steel), xaiv qhov txias txias + meej tshaj - laus.
Kev Tshawb Fawb thiab Kev Kho Kom Zoo: Tom qab tsim khoom, ua qhov kev sim hardness thiab metallographic tsom xam kom paub meej tias tus nqi cua txias tau ua tiav lub hom phiaj tsim. Yog tias qhov hardness siab dhau lawm, nws txhais tau hais tias qhov txias txias yog ceev heev, thiab qhov txias txias yuav tsum tau txo los yog tshaj -kev laus kub / sij hawm yuav tsum tau nce; Yog tias qhov hardness tsawg dhau (siab- lub zog steel tsis ua raws li tus qauv), nws txhais tau hais tias qhov txias txias tsis txaus, thiab lub peev xwm txias yuav tsum tau txhim kho.