t yog hais txog cov khoom siv hlau uas muaj cov khoom siv tib yam, cov qauv siv lead ua, thiab cov khoom siv lub cev, nrog rau cov kev daws teeb meem, cov khoom siv hlau, cov tshuaj ntshiab, thiab lwm yam.
Cov qoob loo loj
Tshaj tawm
[001] Kev ntsuas nruab nrab ntawm cov nplej loj ntawm cov hlau... GB 6394-2002
Cov qoob loo loj
[010] Kev ntsuas ntawm cov nplej loj ntawm cam khwb cia txhuas tooj liab alloys... GB 10852-89
[019] Kev ntsuas qhov nruab nrab ntawm cov nplej loj ntawm pearlite... GB 6394-2002
[062] Kev ntsuas qhov nruab nrab ntawm cov nplej loj ntawm cov hlau... ASTM E112
[074] Cov theem dub thiab dawb thaj tsam thiab qhov ntsuas qhov loj me... BW 2003-01
[149] Kev txiav txim siab ntawm qhov nruab nrab grain loj ntawm cov qauv xim xim... GB 6394-2002
Hlau qauv, cov qauv sab hauv ntawm cov hlau thiab alloys pom los ntawm cov txheej txheem metallographic. Nws muab faib ua 1. macrostructure, 2. microstructure.
Microstructure
Tshaj tawm
Kho kom raug
Metallography yog kev tshawb fawb uas kawm txog cov qauv sab hauv ntawm cov hlau lossis alloys. Tsis tas li ntawd xwb, tab sis kuj kawm txog qhov cuam tshuam ntawm cov qauv sab hauv ntawm cov hlau thiab alloys thaum cov xwm txheej sab nraud thiab sab hauv hloov pauv.
Cov xwm txheej sab nraud yog hais txog qhov kub thiab txias, kev ua deformation, kev txhaj tshuaj, thiab lwm yam. Lub npe hu ua intrinsic yam feem ntau yog xa mus rau cov tshuaj muaj pes tsawg leeg ntawm cov hlau lossis alloys. Hlau qauv qhia txog qhov tshwj xeeb morphology ntawm hlau qauv theem xws li martensite, austenite, ferrite, pearlite, thiab lwm yam.
Austenite
Austenite
1. Austenite - Ib qho kev daws teeb meem uas carbon thiab alloying ntsiab yog yaj hauv -Fe thiab tseem tuav lub ntsej muag-centered cubic lattice ntawm -Fe. Cov ciaj ciam ntawm cov nplej yog cov kab sib txuas thiab tsis tu ncua polygonal, thiab cov austenite khaws cia hauv cov hlau tawv tawv tau muab faib rau hauv qhov sib txawv ntawm martensite.
2. Ferrite
3. 2. Ferrite - Ib qho kev daws teeb meem uas carbon thiab alloying ntsiab yog yaj hauv -Fe. Qhov maj mam txias ferrite nyob rau hauv hypoeutectoid steel yog blocky, thiab thaum cov pa roj carbon ntsiab lus mus txog lub eutectoid muaj pes tsawg leeg, ferrite precipitates nyob rau hauv lub grain ciam teb.
4. Ferrite
5. Cementite
6. 3. Cementite - ib tug compound tsim los ntawm carbon thiab hlau. Nyob rau hauv cov kua hlau-carbon alloys, thawj cementite rau crystallize ib leeg (thawj cementite) yog thaiv-zoo li tsis muaj fab, thaum eutectic cementite yog pob txha. Thaum cov hlau hypereutectoid txias txias, carbides precipitated raws acm kab (secondary cementite) tsim ib lub network, thiab eutectoid cementite ua flaky. Thaum cov hlau-carbon alloys txias hauv qab ar1, cementite (tertiary cementite) precipitates los ntawm ferrite thiab tshwm raws li cov flakes tsis tu ncua ntawm cov cementite thib ob lossis ntawm cov ciam teb.
7. Pearlite
8. 4. Pearlite - ib tug neeg kho tshuab sib tov ntawm ferrite thiab cementite tsim los ntawm eutectoid cov tshuaj tiv thaiv nyob rau hauv hlau-carbon alloys.
9. Qhov kev ncua deb ntawm flakes ntawm pearlite nyob ntawm qhov degree ntawm undercooling thaum lub sij hawm austenite decomposition. Qhov ntau dua qhov undercooling, qhov me dua qhov kev ncua deb ntawm pearlite nplooj ntawv tsim. Nyob rau hauv lub pearlite lamellar txheej tsim ntawm ib tug 1-650 degree C, parallel wide ferrite txheej thiab nyias lamellar cementite yuav txawv nyob rau hauv ib tug metallurgical microscope ntawm ib tug magnification ntawm 400 lub sij hawm los yog ntau tshaj, thiab lawv hu ua ntxhib pearlite thiab lamellar pearlite. Pearlite. Thaum pearlite tsim ntawm 650-600 degree C yog magnified ntawm ib tug magnification ntawm 500 zaug nyob rau hauv ib tug metallurgical microscope, tsuas yog cov dub kab yog pom nyob rau hauv lub cementite ntawm pearlite, thiab lamellar qauv uas tsis tuaj yeem txheeb xyuas tshwj tsis yog tias magnification ntawm ib tug magnification. 1000 zaug yog hu ua troxtenite. Thaum pearlite tsim nyob rau ntawm 600-550 degree C yog magnification ntawm ib tug magnification ntawm 500 lub sij hawm nyob rau hauv ib tug metallurgical microscope, tsuas yog dub pellet zoo li cov qauv pom, thiab lawv tsuas muaj peev xwm txheeb xyuas nyob rau hauv ib tug electron microscope. Lawv hu ua troubadour lub cev.
10. Upper bainite
11. 5. Upper bainite - sib tov ntawm supersaturated acicular ferrite thiab cementite, nrog cementite tam sim no ntawm cov koob ferrite. Ib theem hloov khoom ntawm supercooled austenite ntawm nruab nrab kub (txog 350-550 degree), nws cov duab raug yog ib pob ntawm ze li ntawm ferrite laths nrog misorientation ntawm 6-8od, faib raws lub phaj ntawm txhua lub lath. Qws los yog daim ntawm carbides ua raws li cov axis ntev. Feem ntau, sab sauv bainite yog feather-zoo li, nrog rau cov ciam teb raws li axis ntawm symmetry. Cov plaub tuaj yeem ua symmetric lossis asymmetric, vim tias lawv muaj qhov sib txawv. Lawv tuaj yeem ua tau zoo li rab koob lossis taw tes zoo li, thaiv zoo li. Nyob rau hauv high carbon thiab high alloy steels, cov plaub ntawm koob tsis pom meej, tab sis nyob rau hauv nruab nrab carbon thiab medium alloy steels, cov plaub ntawm cov koob yog ntau txawv thiab cov koob yog txawv heev. . Thaum lub sij hawm hloov pauv, sab sauv bainite thawj cov ntaub ntawv ntawm cov ciam teb nplej thiab loj hlob intragranularly yam tsis hla cov nplej.
12. Qog bainite
13. 6. Lower bainite - Zoo ib yam li saum toj no, tab sis cementite muaj nyob hauv cov koob ferrite. Cov khoom hloov pauv ntawm supercooled austenite ntawm 350 degree ~ ms. Cov duab zoo ib yam yog biconvex lenticular ferrite uas muaj cov roj carbon supersaturated, nyob rau hauv uas cov carbide flakes me me tau faib rau hauv ib qho kev coj ua, thiab hauv cov siv lead ua, lawv zoo li rab koob, thiab cov koob tuaj yeem txuas nrog yam tsis muaj kev hla. Tsis zoo li tempered martensite, martensite tau muab faib ua cov txheej, tab sis cov bainite qis muaj tib xim. Cov pob carbide nyob rau hauv qis bainite yog tuab dua tempered martensite, thiab yooj yim dua corroded thiab tsis tig dub. Nws yog yooj yim eroded. High carbon high alloy steels muaj ntau dua carbide dispersion tshaj cov pa roj carbon tsawg alloy steels, thiab cov koob yog thinner dua li cov uas tsis muaj carbon tsawg alloy steels.
14. Granular bainite
15. 7. Granular bainite - ib tug complex qauv nrog ntau me me Islands tuaj faib nyob rau hauv loj ferrite los yog band-zoo li ferrite. Cov khoom transformation ntawm supercooled austenite nyob rau sab saum toj ntawm bainite transformation kub cheeb tsam. Thaum xub thawj tsim, nws muaj blocky ferrite thiab me me Islands tuaj ntawm carbon-nplua nuj austenite, thiab qee zaum tag nrho cov pa roj carbon-nplua nuj austenite tseem tshuav austenite thaum lub sij hawm tom qab txias. Kev sib xyaw ntawm ferrite thiab cementite (pearlite lossis bainite), feem ntau yuav hloov pauv mus rau hauv martensite thiab ib nrab khaws cia ua ob theem sib xyaw hu ua ma qauv.
16. Carbide-dawb bainite
17. 8. Carbide-free bainite - Ib qho qauv uas muaj ib theem ntawm lath-zoo li ferrite, kuj hu ua ferrite-bainite. Nws qhov tsim kub yog nyob rau sab saum toj ntawm bainite transformation kub cheeb tsam. Nruab nrab ntawm cov laths ntawm ferrite yog carbon-nplua nuj austenite, uas dhau los ua ib qho kev hloov pauv zoo sib xws thaum lub sijhawm txias tom ntej. Carbide-dawb bainite feem ntau tshwm sim nyob rau hauv cov hlau tsis tshua muaj carbon steels thiab nws kuj yog nquag tsim nyob rau hauv steels nrog siab silicon thiab txhuas cov ntsiab lus.
