Txhawm rau ua kom cov hlau ua haujlwm muaj qhov xav tau kev ua haujlwm, cov txheej txheem kho cua sov feem ntau yog qhov tseem ceeb. Cov txheej txheem kev kho cua sov feem ntau suav nrog peb txheej txheem ntawm cua sov, txuag hluav taws xob, thiab cua txias. Vim muaj cov txheej txheem sib txawv, nws tau muab faib ua quenching, tempering, normalizing, thiab annealing. Koj puas tuaj yeem qhia qhov txawv?
01
Dab tsi yog quenching?
Lub quenching ntawm hlau yog kom sov cov hlau mus rau qhov kub siab tshaj qhov tseem ceeb kub Ac3 (hypoeutectoid steel) los yog Ac1 (hypereutectoid steel), kom nws sov rau ib lub sij hawm ntawm lub sij hawm kom nws tag nrho los yog ib nrab austenitized, thiab ces txias nws nrog ib tug sov so. tus nqi cua txias ntau dua qhov tseem ceeb ntawm qhov txias txias. Cov txheej txheem kev kho cua sov kom ceev thiab ceev txias hauv qab Ms (los yog isothermal ze Ms) rau martensite (los yog bainite) transformation. Feem ntau, cov khoom siv kho mob ntawm aluminium alloy, tooj liab alloy, titanium alloy, tempered iav thiab lwm yam ntaub ntawv los yog cov txheej txheem kev kho cua sov nrog cov txheej txheem ceev ceev yog hu ua quenching.
Lub hom phiaj ntawm quenching:
1) Txhim kho cov khoom siv hluav taws xob ntawm cov khoom siv hlau lossis cov khoom siv. Piv txwv li: kev txhim kho lub hardness thiab hnav tsis kam ntawm cov cuab yeej, bearings, thiab lwm yam., ua kom lub elastic txwv ntawm springs, kev txhim kho cov khoom ntawm txhua yam ntawm ncej, thiab lwm yam.
2) Txhim kho cov khoom siv lossis tshuaj lom neeg ntawm qee cov hlau tshwj xeeb. Xws li kev txhim kho corrosion tsis kam ntawm stainless hlau, nce cov hlau nplaum ruaj khov ntawm cov hlau nplaum, thiab lwm yam.
Thaum quenching thiab txias, ntxiv rau qhov tsim nyog xaiv ntawm quenching nruab nrab, txoj kev quenching kom raug. Cov kev siv quenching feem ntau suav nrog ib leeg-kua quenching, ob-kua quenching, qib quenching, isothermal quenching, thiab ib nrab quenching.
Steel workpieces muaj cov yam ntxwv nram qab no tom qab quenching:
① Unbalanced (uas yog, tsis ruaj khov) cov qauv xws li martensite, bainite, thiab khaws cia austenite tau txais.
② Muaj kev ntxhov siab loj sab hauv.
③ Cov khoom siv kho tshuab tsis tuaj yeem ua tau raws li qhov yuav tsum tau ua. Yog li ntawd, steel workpieces feem ntau yuav tsum tau tempered tom qab quenching.
02
Tempering yog dab tsi?
Tempering yog txheej txheem kev kho cua sov uas ua kom sov cov khoom siv hlau los yog qhov chaw rau qhov kub thiab txias, thiab tom qab ntawd txias rau hauv qee txoj kev tom qab tuav rau qee lub sijhawm. Tempering yog ib qho kev ua haujlwm tam sim tom qab quenching, thiab feem ntau yog kev kho cua sov kawg ntawm lub workpiece. Ib txheej txheem, yog li cov txheej txheem sib koom ua ke ntawm quenching thiab tempering yog hu ua kev kho zaum kawg.
Lub hom phiaj tseem ceeb ntawm quenching thiab tempering yog:
1) Txo cov kev ntxhov siab sab hauv thiab txo cov brittleness. Quenched qhov chaw muaj kev ntxhov siab zoo thiab brittleness. Yog hais tias lawv tsis tempered nyob rau hauv lub sij hawm, lawv yuav feem ntau deform los yog txawm tawg.
2) Kho cov khoom siv kho tshuab ntawm lub workpiece. Tom qab quenching, lub workpiece muaj siab hardness thiab siab brittleness. Txhawm rau ua kom tau raws li qhov sib txawv ntawm kev ua haujlwm ntawm ntau lub workpieces, nws tuaj yeem hloov kho los ntawm tempering, hardness, lub zog, plasticity thiab toughness.
3) ruaj khov workpiece loj. Cov qauv metallographic tuaj yeem ruaj khov los ntawm tempering kom ntseeg tau tias tsis muaj deformation yuav tshwm sim thaum siv yav tom ntej.
4) Txhim kho qhov kev ua tau zoo ntawm qee cov hlau alloy.
Lub luag haujlwm ntawm tempering yog:
① Txhim kho qhov ruaj khov ntawm cov qauv, kom cov khoom ua haujlwm yuav tsis muaj kev hloov pauv ntawm cov ntaub so ntswg thaum siv, yog li qhov loj me thiab kev ua haujlwm ntawm lub workpiece yuav ruaj khov.
② Tshem tawm kev ntxhov siab sab hauv txhawm rau txhim kho kev ua haujlwm ntawm cov khoom ua haujlwm thiab ua kom ruaj khov ntawm qhov ntev ntawm lub workpiece.
③ Kho cov khoom siv ntawm cov hlau kom ua tau raws li qhov xav tau ntawm kev siv.
Yog vim li cas vim li cas tempering muaj cov teebmeem no yog tias thaum kub nce, kev ua haujlwm ntawm atoms nce, thiab atoms ntawm hlau, carbon thiab lwm yam alloying ntsiab nyob rau hauv hlau yuav diffuse sai sai kom paub qhov rearrangement ntawm atoms, yog li ua rau lawv tsis ruaj khov. Lub koom haum tsis sib npaug maj mam hloov mus rau hauv lub koom haum ruaj khov. Kev nyem ntawm kev ntxhov siab sab hauv kuj tseem cuam tshuam nrog kev txo qis hauv cov hlau uas muaj zog thaum kub nce. Feem ntau, thaum cov hlau yog tempered, hardness thiab lub zog txo, thiab cov plasticity nce. Qhov siab dua qhov kub thiab txias, qhov hloov pauv ntawm cov khoom siv tshuab no ntau dua. Qee cov hlau alloys nrog cov ntsiab lus siab ntawm cov ntsiab lus alloying yuav ua rau qee qhov zoo-grained hlau tebchaw thaum tempered nyob rau hauv ib tug tej yam kub kub, uas yuav ua rau kom lub zog thiab hardness. Qhov tshwm sim no hu ua Secondary hardening.
Tempering yuav tsum tau: workpieces nrog sib txawv siv yuav tsum tempered ntawm txawv kub kom tau raws li qhov yuav tsum tau ntawm kev siv.
① Txiav cov cuab yeej, bearings, carburized thiab quenched qhov chaw, thiab nto quenched qhov chaw feem ntau yog tempered ntawm kub hauv qab 250 degree. Tom qab qhov ntsuas kub qis, qhov hardness tsis hloov ntau, qhov kev ntxhov siab sab hauv yuav txo qis, thiab qhov toughness zoo dua me ntsis.
② Lub caij nplooj ntoos hlav yog tempered ntawm nruab nrab kub ntawm 350-500 degree kom tau siab elasticity thiab tsim nyog toughness.
③ Cov khoom ua los ntawm cov pa roj carbon monoxide nruab nrab feem ntau yog tempered ntawm qhov kub ntawm 500-600 degree C kom tau txais kev sib xyaw zoo ntawm lub zog thiab tawv.
Thaum cov hlau yog tempered ntawm ib ncig ntawm 300 degree, nws brittleness feem ntau nce. Qhov tshwm sim no yog hu ua thawj hom temper brittleness. Feem ntau, nws yuav tsum tsis txhob tempered nyob rau hauv qhov kub thiab txias. Qee qhov nruab nrab carbon alloy structural steels kuj yuav ua rau nkig yog tias lawv maj mam txias rau hauv chav tsev kub tom qab kub tempering. Qhov tshwm sim no yog hu ua hom thib ob ntawm temper brittleness. Qhov sib ntxiv ntawm molybdenum rau cov hlau, los yog txias hauv cov roj los yog dej thaum lub sij hawm tempering, tuaj yeem tiv thaiv ob hom temper brittleness. Qhov no brittleness yuav raug tshem tawm los ntawm reheating hom thib ob ntawm temper brittle steel rau thawj tempering kub.
Hauv kev tsim khoom, nws feem ntau yog raws li qhov yuav tsum tau ua rau kev ua haujlwm ntawm lub workpiece. Raws li cov cua kub sib txawv, tempering tau muab faib ua qhov kub thiab txias, nruab nrab kub tempering, thiab kub tempering. Cov txheej txheem kev kho cua sov ua ke ua ke quenching thiab tom ntej kub-kub tempering yog hu ua quenching thiab tempering, uas yog, nws muaj zoo plasticity thiab toughness thaum muaj zog siab.
1) Tsawg kub tempering: 150-250 degree, M lub sij hawm, txo cov kev ntxhov siab thiab brittleness, txhim kho cov yas toughness, muaj zog dua thiab hnav tsis kam. Siv los ntsuas cov cuab yeej, riam thiab dov bearings, thiab lwm yam.
2) Tempering ntawm nruab nrab kub: 350-500 degree, T lub sij hawm, nrog siab elasticity, tej yam yas thiab hardness. Siv los ua cov springs, forging tuag, thiab lwm yam.
3) Kub kub tempering: 500-650 degree, S tempering, nrog cov khoom zoo txhua yam. Siv los ua iav, crankshafts, thiab lwm yam.
03
Dab tsi yog normalizing?
Normalizing yog kev kho cua sov uas txhim kho lub toughness ntawm hlau. Tom qab tus tswv cuab hlau tau rhuab mus rau 30-50 degree saum toj no qhov kub ntawm Ac3, nws tau khaws cia rau ib lub sijhawm thiab tom qab ntawd cua txias. Lub ntsiab feature yog tias qhov txias txias yog sai dua annealing thiab qis dua quenching. Thaum lub sij hawm normalizing, cov khoom siv lead ua ntawm cov hlau tuaj yeem ua kom zoo dua hauv qhov txias me ntsis, tsis tsuas yog tuaj yeem tau txais lub zog txaus siab, tab sis kuj tuaj yeem txhim kho toughness (AKV tus nqi), txo qis kev nyiam ntawm cov khoom. Tom qab qee qhov qis-alloy kub-kuav los tiag steel daim hlau, qis-alloy steel forgings thiab castings yog normalized, cov khoom siv txhua yam ntawm cov khoom tuaj yeem txhim kho tau zoo, thiab kev ua haujlwm txiav kuj tseem txhim kho.
Normalizing muaj cov hom phiaj thiab siv hauv qab no:
① Rau cov hlau hypoeutecoid, normalizing yog siv los tshem tawm cov txheej txheem overheated coarse-grained thiab Widmanstatten qauv ntawm castings, forgings, thiab weldments, thiab cov qauv banded hauv cov ntaub ntawv dov; ua kom cov nplej; thiab tuaj yeem siv ua kev kho cua sov ua ntej ua ntej quenching.
② Rau cov hlau hypereutectoid, normalizing tuaj yeem tshem tawm cov reticular theem nrab cementite thiab ua kom zoo pearlite, uas tsis tsuas yog txhim kho cov khoom siv dag zog, tab sis kuj pab txhawb kev spheroidizing annealing tom qab.
③ Rau qis-carbon sib sib zog nqus-dawb daim hlau nyias, normalizing tuaj yeem tshem tawm cov cementite dawb ntawm cov ciam teb txhawm rau txhim kho lawv cov khoom sib sib zog nqus.
④ Rau cov hlau tsis muaj cov pa roj carbon tsawg thiab cov hlau tsis tshua muaj cov hlau tsis tshua muaj hlau, siv cov txheej txheem kom tau txais cov qauv zoo-flaky pearlite ntau dua, ua kom cov tawv tawv rau HB140-190, zam qhov tshwm sim ntawm "nplaum riam" thaum txiav, thiab txhim kho machinability. Rau nruab nrab carbon steel, thaum ob qho tib si normalizing thiab annealing yuav siv tau, nws yog ntau yig thiab yooj yim rau siv normalizing.
⑤ Rau cov qauv nruab nrab-cov pa roj carbon zoo tib yam, normalizing tuaj yeem siv es tsis txhob quenching thiab high-temperature tempering thaum cov khoom siv tsis zoo, uas tsis yog yooj yim rau kev khiav lag luam, tab sis kuj stabilizes cov qauv thiab qhov loj ntawm cov hlau.
⑥ normalizing ntawm qhov kub thiab txias (150-200 degree saum toj no Ac3) tuaj yeem txo qhov sib cais ntawm cov castings thiab forgings vim muaj qhov sib txawv ntawm qhov kub thiab txias. Cov nplej ntxhib tom qab normalizing ntawm qhov kub thiab txias tuaj yeem ua kom zoo dua los ntawm kev ua haujlwm tom qab ntawm qhov kub qis dua thib ob.
⑦ Rau qee qhov qis thiab nruab nrab carbon alloy steels siv nyob rau hauv chav turbines thiab boilers, normalizing feem ntau yog siv kom tau bainite qauv, thiab ces tempered ntawm kub. Nws muaj kev nkag siab zoo thaum siv ntawm 400-550 degree .
⑧ Ntxiv nrog rau cov khoom siv hlau thiab cov khoom siv hlau, normalizing kuj yog siv dav hauv kev kho cua sov ntawm cov hlau kom tau txais pearlite matrix thiab txhim kho lub zog ntawm cov hlau.
Txij li thaum normalizing yog tus cwj pwm los ntawm huab cua txias, ambient kub, stacking txoj kev, airflow thiab workpiece loj tag nrho cov muaj feem xyuam rau cov qauv thiab kev ua tau zoo tom qab normalizing. Cov qauv normalized kuj tseem siv tau raws li kev faib tawm ntawm cov hlau alloy. Feem ntau, alloy steels tau muab faib ua pearlite steel, bainite steel, martensitic steel thiab austenitic steel raws li cov microstructure tau txais los ntawm cua sov cov qauv nrog lub cheeb ntawm 25 hli mus rau 900 degree thiab cua txias.
04
annealing yog dab tsi?
Annealing yog txheej txheem kev kho cua sov hlau uas cov hlau maj mam rhuab mus rau qhov kub thiab txias, khaws cia rau lub sijhawm txaus, thiab tom qab ntawd txias ntawm tus nqi tsim nyog. Kev kho cua sov yog muab faib ua tiav annealing, tsis tiav annealing thiab kev ntxhov siab annealing. Cov khoom siv hluav taws xob ntawm cov ntaub ntawv annealed tuaj yeem kuaj tau los ntawm kev sim tensile lossis hardness test. Ntau cov khoom siv hlau tau muab rau hauv lub xeev ntawm annealing thiab kev kho cua sov. Rockwell hardness tester tuaj yeem siv los ntsuas qhov nyuaj ntawm cov hlau. Rau cov hlau nyias nyias, steel strips thiab nyias-walled steel kav, nto Rockwell hardness testers tuaj yeem siv los kuaj HRT hardness. .
Lub hom phiaj ntawm annealing yog:
① Txhim kho lossis tshem tawm ntau yam kev ua haujlwm tsis zoo thiab cov kev ntxhov siab uas tshwm sim los ntawm steel casting, forging, dov thiab vuam, thiab tiv thaiv deformation thiab tawg ntawm workpieces.
② soften lub workpiece rau txiav.
③ Refining cov nplej thiab txhim kho cov qauv los txhim kho cov khoom ntawm cov khoom ua haujlwm.
④ Ua cov koom haum npaj rau kev kho cua sov zaum kawg (quenching, tempering).
Feem ntau siv cov txheej txheem annealing yog:
① Ua kom tag nrho. Nws yog siv los kho cov qauv coarse superheated nrog cov khoom siv tsis zoo tom qab casting, forging thiab vuam ntawm nruab nrab thiab qis carbon steel. Ua kom sov lub workpiece mus rau 30-50 degree saum toj no qhov kub ntawm qhov uas ferrite yog kiag li hloov mus rau hauv austenite, cia nws sov rau ib lub sij hawm ntawm lub sij hawm, thiab ces txias maj mam nrog lub cub tawg. Thaum lub sij hawm ua kom txias, lub austenite yuav hloov dua siab tshiab los ua cov qauv hlau nyias.
② Spheroidizing annealing. Nws yog siv los txo qhov siab hardness ntawm cov cuab yeej steel thiab bearing steel tom qab forging. Lub workpiece yog rhuab mus rau 20-40 degree siab tshaj qhov kub ntawm cov hlau pib tsim austenite, thiab ces maj mam txias tom qab cua sov preservation. Thaum lub sij hawm txias, lamellar cementite nyob rau hauv lub pearlite ua spherical, yog li txo cov hardness.
③ Isothermal annealing. Nws yog siv los txo qhov siab hardness ntawm qee cov qauv hlau alloy nrog siab nickel thiab chromium cov ntsiab lus rau kev txiav. Feem ntau, nws yog thawj zaug txias rau qhov tsis ruaj khov tshaj plaws ntawm austenite ntawm tus nqi nrawm dua, thiab austenite hloov mus rau hauv troostite lossis sorbite rau lub sijhawm tsim nyog, thiab qhov hardness tuaj yeem txo.
④ Recrystallization annealing. Nws yog siv los tshem tawm qhov tshwm sim hardening (nce hardness thiab txo nyob rau hauv plasticity) ntawm hlau hlau thiab nyias phaj nyob rau hauv tus txheej txheem ntawm txias txias thiab txias dov. Cov cua kub kub feem ntau yog 50-150 degree qis dua qhov kub ntawm cov hlau pib tsim austenite. Tsuas yog nyob rau hauv txoj kev no tuaj yeem ua haujlwm hardening nyhuv yuav raug tshem tawm thiab cov hlau softened.
⑤ Graphitization annealing. Nws yog siv los tig cam khwb cia hlau uas muaj ntau cov cementite rau hauv malleable cam khwb cia hlau nrog zoo plasticity. Cov txheej txheem ua haujlwm yog kom sov lub casting mus txog 950 degree, ua kom sov rau ib lub sij hawm ntawm lub sij hawm thiab ces txias nws kom zoo kom decompose cov cementite los ua ib pawg ntawm flocculent graphite.
⑥ Diffusion annealing. Nws yog siv los homogenize cov tshuaj muaj pes tsawg leeg ntawm alloy castings thiab txhim kho lawv cov kev ua tau zoo. Cov txheej txheem yog ua kom sov lub casting mus rau qhov kub siab tshaj plaws uas tsis muaj melting, thiab ua kom sov rau ib lub sij hawm ntev, thiab ces txias maj mam tom qab lub diffusion ntawm ntau yam nyob rau hauv lub alloy nyhav muab tusyees faib.
⑦ Kev ntxhov siab rau kev ntxhov siab. Siv los tshem tawm cov kev ntxhov siab sab hauv ntawm steel castings thiab weldments. Rau cov khoom siv hlau thiab hlau rhuab mus rau 100-200 degree qis dua qhov kub ntawm austenite pib tsim, cua txias hauv huab cua tom qab kev txuag hluav taws xob tuaj yeem tshem tawm kev ntxhov siab sab hauv.
