Lub ntsiab txhais thiab lub hom phiaj ntawm quenching
Cov hlau yog rhuab mus rau qhov kub siab tshaj qhov tseem ceeb Ac3 (hypoeutectoid steel) los yog Ac1 (hypereutectoid steel), khaws cia rau ib lub sij hawm kom nws tag nrho los yog ib nrab austenitized, thiab ces txias ntawm ib tug ceev ntau tshaj qhov tseem ceeb quenching ceev. Cov txheej txheem kev kho cua sov uas hloov supercooled austenite rau hauv martensite lossis qis dua bainite yog hu ua quenching.
Lub hom phiaj ntawm quenching yog hloov lub supercooled austenite rau hauv martensite los yog bainite kom tau ib tug martensite los yog qis bainite qauv, uas yog ces ua ke nrog tempering ntawm txawv kub kom zoo heev txhim kho lub zog, hardness, thiab kuj ntawm cov hlau. Wearability, qaug zog thiab toughness, thiab lwm yam, kom ua tau raws li qhov kev siv sib txawv ntawm ntau yam khoom siv thiab cov cuab yeej. Quenching kuj tseem siv tau los ua kom tau raws li lub cev tshwj xeeb thiab tshuaj lom neeg ntawm qee cov hlau tshwj xeeb xws li ferromagnetism thiab corrosion kuj.
Thaum cov hlau qhov chaw txias hauv qhov nruab nrab quenching nrog cov kev hloov hauv lub cev, cov txheej txheem txias feem ntau muab faib ua peb theem: vapor film theem, boiling theem, thiab convection theem.
Hardenability ntawm steel
Hardenability thiab hardenability yog ob qhov kev ua tau zoo uas qhia txog lub peev xwm ntawm cov hlau kom dhau quenching. Lawv kuj yog lub hauv paus tseem ceeb rau kev xaiv thiab siv cov khoom siv.
1. Lub ntsiab lus ntawm hardenability thiab hardenability
Hardenability yog lub peev xwm ntawm cov hlau kom ua tiav qhov siab tshaj plaws hardness nws tuaj yeem ua tiav thaum quenched thiab hardened nyob rau hauv zoo tagnrho tej yam kev mob. Lub ntsiab tseem ceeb uas txiav txim siab hardenability ntawm steel yog cov ntsiab lus carbon ntawm cov hlau. Yuav kom meej meej, nws yog cov ntsiab lus carbon yaj hauv austenite thaum quenching thiab cua sov. Qhov siab dua cov ntsiab lus carbon, qhov siab dua qhov hardenability ntawm cov hlau. . Cov ntsiab lus alloying hauv cov hlau tsis tshua muaj kev cuam tshuam rau lub hardenability, tab sis lawv muaj kev cuam tshuam loj heev rau hardenability ntawm cov hlau.
Hardenability yog hais txog cov yam ntxwv uas txiav txim siab qhov tob hardening thiab hardness faib ntawm cov hlau raws li cov xwm txheej. Ntawd yog, lub peev xwm kom tau txais qhov tob ntawm txheej hardened thaum steel quenched. Nws yog ib qho khoom muaj nqis ntawm steel. Hardenability tiag tiag qhia txog qhov yooj yim uas austenite hloov mus rau hauv martensite thaum cov hlau quenched. Nws yog feem ntau cuam tshuam nrog kev ruaj ntseg ntawm supercooled austenite ntawm cov hlau, los yog qhov tseem ceeb quenching txias tus nqi ntawm cov hlau.
Nws yuav tsum tau muab sau tseg tias hardenability ntawm steel yuav tsum tau txawv los ntawm qhov zoo hardening qhov tob ntawm steel qhov chaw nyob rau hauv tej yam kev mob quenching. Lub hardenability ntawm steel yog ib qho cuab yeej ntawm cov hlau nws tus kheej. Nws tsuas yog nyob ntawm nws tus kheej yam tseem ceeb thiab tsis muaj dab tsi cuam tshuam nrog lwm yam. Qhov zoo ntawm hardenability qhov tob ntawm steel tsis tsuas yog nyob ntawm hardenability ntawm cov hlau, tab sis kuj nyob ntawm cov khoom siv. Nws muaj feem xyuam rau lwm yam xws li qhov nruab nrab cua txias thiab workpiece loj. Piv txwv li, nyob rau hauv tib lub austenitizing tej yam kev mob, lub hardenability ntawm tib steel yog tib yam, tab sis qhov zoo hardening qhov tob ntawm cov dej quenching yog loj dua li cov roj quenching, thiab me me qhov chaw yog me dua roj quenching. Qhov zoo hardening qhov tob ntawm qhov loj yog qhov loj. Qhov no tsis tuaj yeem hais tau tias dej quenching muaj zog dua li cov roj quenching. Nws tsis tuaj yeem hais tias qhov me me muaj qhov hardenability ntau dua li qhov loj. Nws tuaj yeem pom tau tias txhawm rau ntsuas qhov hardenability ntawm cov hlau, kev cuam tshuam ntawm lwm yam xws li workpiece zoo, qhov loj, qhov nruab nrab cua txias, thiab lwm yam yuav tsum raug tshem tawm.
Tsis tas li ntawd, vim hardenability thiab hardenability yog ob lub ntsiab lus sib txawv, steel nrog siab hardness tom qab quenching tsis tas yuav muaj siab hardenability; thiab steel nrog tsawg hardness kuj yuav muaj siab hardenability.
2. Yam cuam tshuam rau hardenability
Lub hardenability ntawm steel nyob ntawm qhov ruaj khov ntawm austenite. Txhua yam uas tuaj yeem txhim kho kev ruaj ntseg ntawm supercooled austenite, hloov C nkhaus mus rau sab xis, thiab yog li txo qhov tseem ceeb ntawm qhov txias txias tuaj yeem txhim kho cov hardenability ntawm cov hlau siab. Kev ruaj ntseg ntawm austenite feem ntau yog nyob ntawm nws cov tshuaj muaj pes tsawg leeg, grain loj thiab muaj pes tsawg leeg uniformity, uas muaj feem xyuam rau cov tshuaj muaj pes tsawg leeg ntawm cov hlau thiab cua sov tej yam kev mob.
3.Measurement method of hardenability
Muaj ntau txoj hauv kev los ntsuas qhov hardenability ntawm cov hlau, feem ntau yog siv los ntsuas txoj kab uas hla thiab qhov kawg-hardenability test method.
(1) Txoj kev ntsuas txoj kab uas hla tseem ceeb
Tom qab cov hlau yog quenched nyob rau hauv ib tug tej yam nruab nrab, lub siab tshaj plaws txoj kab uas hla thaum cov tub ntxhais tau txais tag nrho cov martensite los yog 50% martensite qauv yog hu ua qhov tseem ceeb txoj kab uas hla, sawv cev los ntawm Dc. Txoj kev ntsuas txoj kab uas hla tseem ceeb yog ua kom muaj cov kab sib txuas nrog cov kab sib txawv, thiab tom qab quenching, ntsuas qhov hardness U nkhaus faib raws txoj kab uas hla ntawm txhua seem seem, thiab nrhiav tus pas nrig nrog cov qauv semi-martensite nyob hauv nruab nrab. Txoj kab uas hla ntawm tus pas nrig round Qhov ntawd yog qhov tseem ceeb txoj kab uas hla. Qhov loj dua qhov tseem ceeb txoj kab uas hla, qhov siab dua qhov hardenability ntawm cov hlau.
(2) Xaus quenching test method
Txoj kev xeem kawg-quenching siv tus qauv loj kawg-quenched specimen (Ф25mm × 100mm). Tom qab austenitization, dej yog txau rau ntawm ib kawg ntawm cov qauv ntawm cov cuab yeej tshwj xeeb kom txias nws. Tom qab txias, lub hardness yog ntsuas raws axis kev taw qhia - los ntawm cov dej-txias kawg. Test txoj kev rau kev sib raug zoo nkhaus. Qhov kawg-hardening test method yog ib txoj hauv kev los txiav txim siab hardenability ntawm steel. Nws qhov zoo yog kev ua haujlwm yooj yim thiab kev siv dav dav.
4.Quenching kev ntxhov siab, deformation thiab tawg
(1) Internal stress ntawm lub workpiece thaum quenching
Thaum lub workpiece txias sai heev nyob rau hauv lub quenching nruab nrab, txij li thaum lub workpiece muaj ib tug me me thiab thermal conductivity coefficient kuj yog ib tug tej yam nqi, ib tug tej yam kub gradient yuav tshwm sim nyob rau hauv lub puab seem ntawm lub workpiece thaum lub sij hawm txias. Qhov kub ntawm qhov chaw yog qhov tsawg, qhov kub ntawm qhov tseem ceeb yog siab, thiab qhov kub thiab txias ntawm qhov tseem ceeb yog siab. Nws muaj qhov kub thiab txias. Thaum lub caij txias ntawm lub workpiece, kuj tseem muaj ob lub cev tshwm sim: ib qho yog thermal expansion, raws li qhov kub thiab txias, txoj kab ntev ntawm lub workpiece yuav shrinkage; Lwm qhov yog qhov hloov pauv ntawm austenite rau martensite thaum qhov kub thiab txias poob mus rau martensite transformation point. , uas yuav ua rau kom cov ntim tshwj xeeb. Vim qhov sib txawv ntawm qhov kub thiab txias thaum lub caij txias, tus nqi ntawm thermal expansion yuav txawv ntawm qhov sib txawv ntawm qhov sib txawv ntawm qhov chaw ua haujlwm, thiab kev ntxhov siab sab hauv yuav tsim nyob rau hauv ntau qhov chaw ntawm lub workpiece. Vim muaj qhov sib txawv ntawm qhov kub thiab txias hauv qhov chaw ua haujlwm, kuj tseem yuav muaj qhov chaw uas qhov kub thiab txias poob sai dua li qhov chaw uas martensite tshwm sim. Kev hloov pauv, qhov ntim nthuav dav, thiab qhov chaw uas muaj qhov kub thiab txias tseem siab dua qhov taw tes thiab tseem nyob hauv lub xeev austenite. Cov khoom sib txawv no tseem yuav ua rau muaj kev ntxhov siab sab hauv vim qhov sib txawv ntawm qhov hloov pauv tshwj xeeb. Yog li, ob hom kev ntxhov siab sab hauv yuav raug tsim thaum lub sij hawm quenching thiab txias txheej txheem: ib qho yog thermal stress; lwm yam yog cov ntaub so ntswg stress.
Raws li lub sijhawm muaj nyob ntawm tus yam ntxwv ntawm kev ntxhov siab sab hauv, nws tuaj yeem muab faib ua kev ntxhov siab tam sim thiab qhov kev ntxhov siab. Cov kev ntxhov siab sab hauv tsim los ntawm cov khoom ua haujlwm ntawm ib lub sijhawm thaum lub sijhawm txias yog hu ua kev ntxhov siab tam sim; Tom qab lub workpiece txias lawm, qhov kev ntxhov siab nyob rau hauv lub workpiece yog hu ua residual stress.
Thermal stress yog hais txog cov kev ntxhov siab uas tshwm sim los ntawm qhov tsis sib xws ntawm thermal expansion (lossis txias contraction) vim qhov kub thiab txias sib txawv ntawm qhov sib txawv ntawm qhov chaw ua haujlwm thaum nws yog cua sov (los yog txias).
Tam sim no coj ib lub tog raj kheej ua piv txwv los piav qhia txog kev tsim thiab hloov cov cai ntawm kev ntxhov siab sab hauv thaum nws cov txheej txheem txias. Tsuas yog qhov kev ntxhov siab axial tham ntawm no. Thaum pib ntawm kev ua kom txias, vim tias qhov chaw txias sai sai, qhov kub thiab txias yog qis, thiab shrinks ntau, thaum cov tub ntxhais txias txias, qhov kub yog siab, thiab lub shrinkage yog me me. Raws li qhov tshwm sim, qhov saum npoo thiab sab hauv yog sib koom ua ke, ua rau muaj kev ntxhov siab tensile ntawm qhov chaw, thaum lub hauv paus tseem ceeb. kev ntxhov siab. Raws li kev ua kom txias, qhov kub ntawm qhov sib txawv ntawm sab hauv thiab sab nraud nce, thiab kev ntxhov siab sab hauv kuj nce raws li. Thaum qhov kev ntxhov siab nce siab tshaj qhov tawm los lub zog ntawm qhov kub no, cov yas deformation tshwm sim. Txij li thaum lub thickness ntawm lub plawv siab tshaj qhov saum npoo, lub plawv ib txwm cog lus axially ua ntej. Raws li qhov tshwm sim ntawm cov yas deformation, qhov kev ntxhov siab sab hauv tsis nce ntxiv lawm. Tom qab txias rau qee lub sijhawm, qhov txo qis hauv qhov kub thiab txias yuav maj mam qeeb, thiab nws cov shrinkage kuj yuav maj mam txo. Lub sijhawm no, cov tub ntxhais tseem tab tom shrinking, yog li lub tensile kev nyuaj siab ntawm qhov chaw thiab compressive kev nyuaj siab ntawm cov tub ntxhais yuav maj mam txo kom txog thaum lawv ploj. Txawm li cas los xij, raws li kev ua kom txias mus ntxiv, cov av noo ntawm qhov chaw yuav qis dua thiab qis dua, thiab cov nqi ntawm cov shrinkage yuav tsawg thiab tsawg dua, lossis txawm tias nres. Txij li thaum qhov kub ntawm cov tub ntxhais tseem siab, nws yuav txuas ntxiv mus, thiab thaum kawg compressive kev nyuaj siab yuav raug tsim nyob rau saum npoo ntawm lub workpiece, thaum lub tub ntxhais yuav muaj tensile kev nyuaj siab. Txawm li cas los xij, txij li qhov kub tsis tshua muaj, cov yas deformation tsis yooj yim tshwm sim, yog li qhov kev ntxhov siab no yuav nce ntxiv raws li kev ua kom txias. Nws tseem nce ntxiv thiab thaum kawg tseem nyob hauv lub workpiece li residual stress.
Nws tuaj yeem pom tau tias qhov kev ntxhov siab thermal thaum lub sijhawm ua kom txias pib ua rau cov txheej txheem saum npoo yuav tsum tau ncab thiab cov tub ntxhais yuav tsum tau compressed, thiab qhov seem seem ntawm qhov kev ntxhov siab yog cov txheej txheej saum npoo yuav tsum tau compressed thiab cov tub ntxhais yuav tsum tau ncab.
Raws li cov ntsiab lus, cov thermal stress generated thaum lub sij hawm quenching txias yog tshwm sim los ntawm qhov sib txawv ntawm qhov kub thiab txias thaum lub sij hawm txias. Qhov ntau dua qhov txias thiab qhov sib txawv ntawm qhov sib txawv ntawm qhov sib txawv, qhov ntau dua qhov thermal stress generated. Nyob rau hauv tib lub caij txias nruab nrab, qhov kub ntawm qhov chaw ua haujlwm ntau dua, qhov loj dua, qhov me me ntawm cov thermal conductivity ntawm cov hlau, qhov kub ntawm qhov sib txawv ntawm qhov workpiece ntau dua, thiab qhov thermal stress ntau dua. Yog hais tias lub workpiece txias tsis sib npaug ntawm qhov kub thiab txias, nws yuav deformed thiab deformed. Yog hais tias lub zog tensile instantaneous generated thaum lub sij hawm txias ntawm lub workpiece yog ntau tshaj lub tensile lub zog ntawm cov khoom, quenching tawg yuav tshwm sim.
Phase transformation stress yog hais txog qhov kev ntxhov siab uas tshwm sim los ntawm lub sijhawm sib txawv ntawm lub sijhawm hloov pauv hauv ntau qhov chaw ntawm lub workpiece thaum lub sijhawm kho cua sov, tseem hu ua cov ntaub so ntswg ntxhov siab.
Thaum lub sij hawm quenching thiab ceev txias, thaum txheej txheej yog txias rau Ms point, martensitic transformation tshwm sim thiab ua rau ntim expansion. Txawm li cas los xij, vim qhov kev cuam tshuam ntawm cov tub ntxhais tseem tsis tau hloov pauv, cov txheej txheem saum npoo ua rau muaj kev ntxhov siab, thaum cov tub ntxhais muaj kev ntxhov siab tensile. Thaum qhov kev ntxhov siab loj txaus, nws yuav ua rau deformation. Thaum cov tub ntxhais txias txias rau Ms point, nws tseem yuav raug hloov pauv martensitic thiab nthuav dav hauv ntim. Txawm li cas los xij, vim muaj kev txwv ntawm cov txheej txheem hloov pauv nrog cov yas qis thiab lub zog siab, nws qhov kev ntxhov siab zaum kawg yuav nyob rau hauv daim ntawv ntawm qhov nro, thiab cov tub ntxhais yuav nyob rau hauv siab. Nws tuaj yeem pom tau tias qhov kev hloov pauv thiab lub xeev kawg ntawm theem kev hloov pauv kev ntxhov siab yog qhov txawv ntawm qhov kev ntxhov siab thermal. Tsis tas li ntawd, txij li theem hloov kev ntxhov siab tshwm sim ntawm qhov kub thiab txias tsis tshua muaj plasticity, deformation yog qhov nyuaj rau lub sijhawm no, yog li theem hloov kev ntxhov siab yuav ua rau tawg ntawm workpiece.
Muaj ntau yam uas cuam tshuam rau qhov loj ntawm theem kev hloov pauv kev ntxhov siab. Qhov ceev ntawm qhov txias txias ntawm cov hlau nyob rau hauv martensite transformation kub ntau, qhov loj ntawm cov hlau daim, qhov phem thermal conductivity ntawm cov hlau, qhov loj qhov tshwj xeeb ntim ntawm martensite, ntau dua cov theem transformation kev nyuaj siab. Qhov loj dua nws tau txais. Tsis tas li ntawd, cov theem kev hloov pauv kev ntxhov siab kuj tseem cuam tshuam nrog cov khoom ntawm cov hlau thiab hardenability ntawm cov hlau. Piv txwv li, high carbon high alloy steel tsub kom qhov tshwj xeeb ntim ntawm martensite vim nws cov ntsiab lus carbon siab, uas yuav tsum tau nce lub theem transformation kev nyuaj siab ntawm steel. Txawm li cas los xij, raws li cov ntsiab lus ntawm cov pa roj carbon monoxide nce, Ms taw tes txo qis, thiab muaj ntau qhov khaws cia austenite tom qab quenching. Nws qhov ntim nthuav dav txo qis thiab qhov seem kev ntxhov siab tsawg.
(2) Deformation ntawm lub workpiece thaum quenching
Thaum lub sij hawm quenching, muaj ob lub ntsiab ntawm deformation nyob rau hauv lub workpiece: ib tug yog qhov kev hloov nyob rau hauv lub geometric duab ntawm lub workpiece, uas yog manifested raws li kev hloov nyob rau hauv loj thiab zoo, feem ntau hu ua warping deformation, uas yog tshwm sim los ntawm quenching kev nyuaj siab; Lwm qhov yog ntim deformation. , uas manifests nws tus kheej raws li ib tug proportional expansion los yog contraction ntawm lub ntim ntawm lub workpiece, uas yog tshwm sim los ntawm kev hloov nyob rau hauv tej ntim thaum lub sij hawm hloov theem.
Warping deformation kuj suav nrog cov duab deformation thiab twisting deformation. Twist deformation feem ntau yog tshwm sim los ntawm qhov tsis raug ntawm qhov chaw ua haujlwm hauv lub qhov cub thaum cua sov, lossis tsis muaj kev kho mob tom qab deformation kho ua ntej quenching, los yog tsis sib xws ntawm ntau qhov chaw ntawm lub workpiece thaum lub workpiece txias. Qhov deformation no tuaj yeem txheeb xyuas thiab daws tau rau qee qhov xwm txheej. Cov hauv qab no feem ntau tham txog ntim deformation thiab cov duab deformation.
1) Ua rau quenching deformation thiab nws cov kev hloov pauv
Volume deformation tshwm sim los ntawm cov qauv kev hloov pauv Cov txheej txheem ntawm lub workpiece ua ntej quenching feem ntau pearlite, uas yog, cov qauv sib xyaw ntawm ferrite thiab cementite, thiab tom qab quenching nws yog cov qauv martensitic. Qhov sib txawv tshwj xeeb ntim ntawm cov ntaub so ntswg yuav ua rau lub ntim hloov ua ntej thiab tom qab quenching, uas ua rau deformation. Txawm li cas los xij, qhov deformation tsuas yog ua rau lub workpiece nthuav thiab cog lus proportionally, yog li nws tsis hloov cov duab ntawm lub workpiece.
Tsis tas li ntawd, qhov ntau martensite nyob rau hauv cov qauv tom qab kev kho cua sov, los yog ntau dua cov pa roj carbon ntsiab lus nyob rau hauv martensite, qhov ntau dua nws ntim expansion, thiab ntau npaum li cas ntawm khaws cia austenite, lub ntim tsawg dua expansion. Yog li, qhov kev hloov pauv tuaj yeem tswj tau los ntawm kev tswj cov ntsiab lus txheeb ze ntawm martensite thiab residual martensite thaum kho cua sov. Yog tias tswj tau zoo, lub ntim yuav tsis nthuav lossis qis.
Cov duab deformation tshwm sim los ntawm thermal stress Deformation tshwm sim los ntawm thermal stress tshwm sim nyob rau hauv high kub qhov chaw uas lub yield zog ntawm steel qhov chaw yog tsawg, lub plasticity yog siab, nto txias sai sai, thiab qhov kub ntawm qhov sib txawv ntawm sab hauv thiab sab nraud ntawm lub workpiece yog qhov loj tshaj plaws. Thaum lub sij hawm no, lub instantaneous thermal stress yog deg tensile stress thiab core compressive stress. Txij li thaum cov tub ntxhais kub siab nyob rau lub sij hawm no, lub zog tawm los yog qis dua qhov saum npoo, yog li nws tshwm sim raws li deformation nyob rau hauv qhov kev txiav txim ntawm ntau txoj kev compressive kev nyuaj siab, uas yog, lub voos xwmfab yog kheej kheej nyob rau hauv kev coj. Ntau yam. Qhov tshwm sim yog tias qhov loj dua shrinks, thaum lub me expands. Piv txwv li, lub tog raj kheej ntev luv luv nyob rau hauv qhov ntev kev taw qhia thiab nthuav nyob rau hauv txoj kab uas hla.
Cov duab deformation tshwm sim los ntawm cov ntaub so ntswg kev ntxhov siab Deformation los ntawm cov ntaub so ntswg kev nyuaj siab kuj tshwm sim thaum ntxov thaum cov ntaub so ntswg kev nyuaj siab siab tshaj plaws. Lub sijhawm no, qhov sib txawv ntawm qhov sib txawv ntawm qhov sib txawv yog qhov loj, qhov kub ntawm qhov tseem ceeb yog siab dua, nws tseem nyob rau hauv lub xeev austenite, lub plasticity yog qhov zoo, thiab lub zog tawm los yog tsawg. Cov ntaub so ntswg instantaneous kev nyuaj siab yog nto compressive kev nyuaj siab thiab core tensile stress. Yog li ntawd, lub deformation yog manifested raws li lub elongation ntawm cov tub ntxhais nyob rau hauv qhov kev txiav txim ntawm multi-directional tensile kev nyuaj siab. Qhov tshwm sim yog tias nyob rau hauv qhov kev txiav txim ntawm cov ntaub so ntswg kev ntxhov siab, sab loj ntawm lub workpiece elongates, thaum lub me me shortens. Piv txwv li, qhov deformation tshwm sim los ntawm cov ntaub so ntswg kev ntxhov siab nyob rau hauv ib lub tog raj kheej ntev yog elongation nyob rau hauv ntev thiab txo txoj kab uas hla.
Table 5.3 qhia txog quenching deformation cov cai ntawm ntau yam steel qhov chaw.
2) Cov yam ntxwv cuam tshuam rau quenching deformation
Cov yam ntxwv uas cuam tshuam rau quenching deformation feem ntau yog cov tshuaj muaj pes tsawg leeg ntawm cov hlau, cov qauv qub, cov geometry ntawm cov khoom thiab cov txheej txheem kho cua sov.
3) Quenching kab nrib pleb
Kev tawg nyob rau hauv qhov chaw feem ntau tshwm sim nyob rau hauv lub lig theem ntawm quenching thiab txias, uas yog, tom qab lub martensitic transformation yeej ib txwm ua tiav los yog tom qab ua tiav txias, nkig tsis ua hauj lwm tshwm sim vim hais tias lub tensile kev nyuaj siab nyob rau hauv qhov chaw tshaj lub puas lub zog ntawm cov hlau. Cracks feem ntau yog perpendicular rau cov kev taw qhia ntawm qhov siab tshaj plaws tensile deformation, yog li cov ntaub ntawv sib txawv ntawm cov kab nrib pleb feem ntau nyob ntawm lub xeev kev ntxhov siab.
Hom kev quenching tej kab nrib pleb: Ntev (axial) cov kab nrib pleb yog tsim los thaum lub tangential tensile kev nyuaj siab tshaj lub zog tawg ntawm cov khoom; Cov kab nrib pleb yog tsim thaum qhov loj axial tensile kev nyuaj siab tsim nyob rau hauv lub puab nto ntawm ib feem ntau tshaj lub zog tawg ntawm cov khoom. Kev tawg; network tawg yog tsim nyob rau hauv qhov kev txiav txim ntawm ob-dimensional tensile kev nyuaj siab rau saum npoo; tev cov kab nrib pleb tshwm sim nyob rau hauv ib txheej nyias nyias, uas tej zaum yuav tshwm sim thaum kev ntxhov siab hloov sharply thiab ntau tensile kev nyuaj siab ua nyob rau hauv radial kev taw qhia. Hom tawg.
Cov kab nrib pleb ntev kuj hu ua axial tawg. Cov kab nrib pleb tshwm sim ntawm qhov siab tshaj plaws tensile kev nyuaj siab nyob ze ntawm qhov chaw, thiab muaj qee qhov tob ntawm qhov chaw. Cov kev taw qhia ntawm cov kab nrib pleb feem ntau yog sib npaug mus rau axis, tab sis cov kev taw qhia kuj tseem yuav hloov tau thaum muaj kev ntxhov siab nyob rau hauv ib feem lossis thaum muaj kev puas tsuaj sab hauv.
Tom qab lub workpiece yog kiag li quenched, longitudinal tawg yog nquag tshwm sim. Qhov no muaj feem xyuam rau qhov loj tangential tensile kev nyuaj siab nyob rau saum npoo ntawm quenched workpiece. Raws li cov ntsiab lus ntawm cov pa roj carbon monoxide ntawm cov hlau nce, qhov nyiam ua rau cov kab nrib pleb ntev nce. Tsawg carbon steel muaj qhov tshwj xeeb ntim me me ntawm martensite thiab muaj zog thermal stress. Muaj ib qho loj residual compressive kev ntxhov siab rau ntawm qhov chaw, yog li nws tsis yooj yim rau quenched. Raws li cov ntsiab lus ntawm cov pa roj carbon monoxide nce, qhov kev ntxhov siab ntawm qhov chaw compressive txo qis thiab cov txheej txheem kev ntxhov siab nce ntxiv. Nyob rau tib lub sijhawm, lub siab tensile kev nyuaj siab txav mus rau txheej txheej. Yog li ntawd, high carbon steel yog nquag mus rau longitudinal quenching kab nrib pleb thaum overheated.
Qhov loj ntawm qhov chaw ncaj qha cuam tshuam qhov loj thiab kev faib tawm ntawm qhov seem ntawm kev ntxhov siab, thiab nws txoj kev sib tw tawg kuj txawv. Cov kab nrib pleb ntev kuj tau yooj yim tsim los ntawm quenching nyob rau hauv qhov chaw muaj kev phom sij loj. Tsis tas li ntawd, qhov thaiv ntawm steel raw cov ntaub ntawv feem ntau ua rau cov kab nrib pleb ntev. Txij li cov hlau feem ntau yog ua los ntawm dov, tsis yog kub inclusions, carbides, thiab lwm yam nyob rau hauv cov hlau yog faib raws li deformation kev taw qhia, ua rau cov hlau yuav anisotropic. Piv txwv li, yog tias cov cuab yeej hlau muaj cov qauv zoo li cov qauv, nws lub zog tawg tawg tom qab quenching yog 30% mus rau 50% me dua li qhov ntev ntawm lub zog tawg. Yog tias muaj ntau yam xws li cov tsis kub kub hauv cov hlau uas ua rau muaj kev ntxhov siab, txawm tias qhov kev ntxhov siab tangential ntau dua li qhov kev ntxhov siab axial, cov kab nrib pleb ntev yog yooj yim tsim nyob rau hauv cov kev ntxhov siab tsawg. Vim li no, kev tswj hwm nruj ntawm qib ntawm cov khoom tsis yog xim hlau thiab cov suab thaj hauv cov hlau yog qhov tseem ceeb hauv kev tiv thaiv quenching tawg.
Cov yam ntxwv ntawm kev ntxhov siab sab hauv ntawm cov kab nrib pleb thiab cov kab nrib pleb yog: qhov saum npoo yuav raug kev nyuaj siab. Tom qab tawm ntawm qhov chaw rau ib qho kev ncua deb, lub compressive kev nyuaj siab hloov mus rau ib tug loj tensile kev nyuaj siab. Cov kab nrib pleb tshwm sim hauv thaj tsam ntawm tensile kev nyuaj siab, thiab tom qab ntawd thaum muaj kev ntxhov siab sab hauv Nws kis mus rau qhov chaw ntawm qhov chaw tsuas yog tias nws tau rov faib dua lossis cov nkig ntawm cov hlau txuas ntxiv.
Cov kab nrib pleb feem ntau tshwm sim hauv cov ncej loj, xws li cov chais, turbine rotors lossis lwm yam ncej. Cov yam ntxwv ntawm cov kab nrib pleb yog tias lawv yog perpendicular rau axis kev taw qhia thiab tawg ntawm sab hauv mus rau sab nraud. Lawv feem ntau tsim ua ntej hardened thiab yog tshwm sim los ntawm thermal stress. Cov forgings loj feem ntau muaj qhov tsis xws luag xws li qhov pores, suav nrog, forging tawg thiab pob dawb. Cov kev tsis xws li no yog qhov pib ntawm pob txha thiab tawg nyob rau hauv qhov kev txiav txim ntawm axial tensile stress. Arc tawg yog tshwm sim los ntawm thermal stress thiab feem ntau yog faib rau hauv ib qho arc duab ntawm qhov chaw uas cov duab ntawm ib feem hloov. Nws feem ntau tshwm sim hauv qhov chaw ua haujlwm lossis ze ntawm cov npoo ntse, grooves thiab qhov, thiab muab faib rau hauv cov duab arc. Thaum high-carbon steel qhov chaw nrog ib txoj kab uas hla los yog thickness ntawm 80 mus rau 100 mm los yog ntau tshaj yog tsis quenched, nto yuav qhia compressive kev nyuaj siab thiab qhov chaw yuav qhia tensile kev nyuaj siab. Kev ntxhov siab, qhov siab tshaj plaws tensile kev nyuaj siab tshwm sim nyob rau hauv qhov kev hloov ntawm cheeb tsam los ntawm cov hardened txheej mus rau lub non-hardened txheej, thiab arc tawg tshwm sim nyob rau hauv cov cheeb tsam no. Tsis tas li ntawd, qhov txias txias ntawm cov npoo ntse thiab cov ces kaum yog nrawm thiab txhua yam yog quenched. Thaum hloov mus rau qhov chaw mos, uas yog, mus rau thaj chaw tsis muaj zog, qhov siab tshaj plaws tensile kev ntxhov siab tshwm sim ntawm no, yog li cov kab nrib pleb yog qhov tshwm sim. Qhov cua txias nyob ze ntawm tus pin qhov, zawj lossis qhov nruab nrab ntawm lub workpiece yog qeeb, cov txheej txheem hardened yog nyias, thiab lub tensile kev nyuaj siab nyob ze ntawm lub hardened transition cheeb tsam yuav yooj yim ua rau arc tawg.
Reticular cracks, tseem hu ua deg tawg, yog cov kab nrib pleb. Qhov tob ntawm qhov tawg yog qhov ntiav, feem ntau nyob ib ncig ntawm 0.01 ~ 1.5mm. Lub ntsiab yam ntxwv ntawm no hom ntawm tawg yog hais tias arbitrary kev taw qhia ntawm lub tawg tsis muaj dab tsi ua nrog rau cov duab ntawm ib feem. Ntau cov kab nrib pleb txuas nrog rau ib leeg los tsim ib lub network thiab nthuav dav. Thaum qhov tawg qhov tob loj dua, xws li ntau dua 1 hli, cov yam ntxwv ntawm lub network ploj mus thiab ua randomly oriented los yog longitudinally faib cov kab nrib pleb. Cov kab nrib pleb muaj feem cuam tshuam rau lub xeev ntawm ob-seem tensile kev nyuaj siab ntawm qhov chaw.
Cov pa roj carbon siab lossis carburized steel qhov chaw nrog cov txheej txheem decarburized rau saum npoo yog nquag tsim cov kab nrib pleb thaum lub sijhawm quenching. Qhov no yog vim tias txheej txheej saum npoo muaj cov ntsiab lus qis dua thiab cov ntim me me dua li txheej sab hauv ntawm martensite. Thaum quenching, txheej txheej ntawm carbide yog raug rau tensile kev nyuaj siab. Qhov chaw uas nws dephosphorization txheej tsis tau raug tshem tawm tag nrho thaum lub sij hawm ua tshuab yuav kuj tsim cov kab nrib pleb thaum lub sij hawm high-frequency los yog nplaim taws quenching. Txhawm rau kom tsis txhob muaj cov kab nrib pleb zoo li no, qhov zoo ntawm qhov chaw yuav tsum tau tswj nruj me ntsis, thiab oxidation vuam yuav tsum tau tiv thaiv thaum kho cua sov. Tsis tas li ntawd, tom qab lub forging tuag yog siv rau ib lub sij hawm ntawm lub sij hawm, thermal qaug zog tawg uas tshwm sim nyob rau hauv ib daim hlab los yog tes hauj lwm nyob rau hauv cov kab noj hniav thiab cov kab nrib pleb nyob rau hauv cov txheej txheem sib tsoo ntawm quenched qhov chaw tag nrho yog nyob rau hauv daim ntawv no.
Peeling kab nrib pleb tshwm sim nyob rau hauv ib qho chaw nqaim heev ntawm txheej txheej. Compressive stress ua nyob rau hauv axial thiab tangential cov lus qhia, thiab tensile kev nyuaj siab tshwm sim nyob rau hauv lub radial kev taw qhia. Cov kab nrib pleb yog sib npaug rau qhov chaw ntawm qhov chaw. Lub tev tawm ntawm cov txheej tawv tawv tom qab quenching thiab carburizing qhov chaw txias yog rau cov kab nrib pleb. Nws qhov tshwm sim yog cuam tshuam nrog cov qauv tsis sib xws hauv txheej hardened. Piv txwv li, tom qab alloy carburized steel yog txias ntawm ib tug ceev ceev, cov qauv nyob rau hauv lub carburized txheej yog: txheej txheej zoo heev pearlite + carbide, thiab sublayer yog martensite + residual Austenite, lub puab txheej yog zoo pearlite los yog zoo heev pearlite qauv. Txij li thaum qhov tsim tshwj xeeb ntim ntawm sub-layer martensite yog qhov loj tshaj plaws, qhov tshwm sim ntawm qhov ntim nthuav dav yog qhov kev ntxhov siab ua rau ntawm txheej txheej hauv axial thiab tangential cov lus qhia, thiab tensile kev nyuaj siab tshwm sim nyob rau hauv radial kev taw qhia, thiab kev ntxhov siab hloov mus rau sab hauv, hloov mus rau compressive kev nyuaj siab lub xeev, thiab tev tawm cov kab nrib pleb tshwm sim nyob rau hauv tsis tshua muaj siab nyias qhov chaw. Feem ntau, cov kab nrib pleb lurk nyob rau hauv parallel mus rau saum npoo, thiab nyob rau hauv mob hnyav yuav ua rau nto tev. Yog tias qhov cua txias ntawm cov khoom carburized yog nrawm lossis txo, cov qauv martensite tsis sib xws lossis cov qauv pearlite ultra-fine tuaj yeem tau txais hauv cov txheej txheem carburized, uas tuaj yeem tiv thaiv qhov tshwm sim ntawm cov kab nrib pleb. Tsis tas li ntawd, thaum lub sij hawm high-frequency los yog nplaim taws quenching, qhov saum npoo yog feem ntau overheated thiab cov yam ntxwv inhomogeneity raws lub hardened txheej yuav yooj yim tsim xws li nto tawg.
Microcracks txawv ntawm plaub kab lus hais saum toj no uas lawv tshwm sim los ntawm microstress. Intergranular tawg uas tshwm sim tom qab quenching, overheating thiab sib tsoo ntawm high-carbon cuab yeej hlau los yog carburized workpieces, raws li zoo raws li cov kab nrib pleb tshwm sim los ntawm tsis raws sij hawm tempering ntawm quenched qhov chaw, tag nrho cov muaj feem xyuam rau lub hav zoov thiab tom ntej expansion ntawm microcracks nyob rau hauv cov hlau.
Microcracks yuav tsum tau soj ntsuam nyob rau hauv ib lub tshuab microscope. Lawv feem ntau tshwm sim ntawm thawj austenite grain ciam teb los yog ntawm qhov sib tshuam ntawm cov nplooj ntawv martensite. Qee cov kab nrib pleb nkag mus rau cov nplooj ntawv martensite. Kev tshawb fawb qhia tias microcracks muaj ntau dua nyob rau hauv flaky twinned martensite. Yog vim li cas yog qhov flaky martensite sib tsoo nrog ib leeg thaum loj hlob ntawm kev kub ceev thiab ua rau muaj kev ntxhov siab. Txawm li cas los xij, cov twinned martensite nws tus kheej yog nkig thiab tsis tuaj yeem tsim cov yas deformation relaxes kev ntxhov siab, yog li yooj yim ua rau microcracks. Cov nplej austenite yog ntxhib thiab qhov cuam tshuam rau microcracks nce. Lub xub ntiag ntawm microcracks nyob rau hauv cov hlau yuav txo tau lub zog thiab plasticity ntawm lub quenched qhov chaw, ua rau thaum ntxov puas (pob txha) ntawm qhov chaw.
Txhawm rau kom tsis txhob muaj cov microcracks nyob rau hauv high-carbon steel qhov chaw, ntsuas xws li qis quenching cua sov kub, tau txais cov qauv zoo martensite, thiab txo cov ntsiab lus carbon hauv martensite tuaj yeem txais yuav. Tsis tas li ntawd, lub sijhawm tempering tom qab quenching yog ib txoj hauv kev zoo los txo cov kev ntxhov siab sab hauv. Cov kev ntsuam xyuas tau ua pov thawj tias tom qab txaus tempering siab tshaj 200 ° C, cov carbides precipitated ntawm cov kab nrib pleb muaj cov nyhuv ntawm "welding" cov kab nrib pleb, uas tuaj yeem txo qhov phom sij ntawm microcracks.
Cov saum toj no yog ib qho kev sib tham ntawm cov laj thawj thiab kev tiv thaiv ntawm cov kab nrib pleb raws li tus qauv tawg tawg. Hauv kev tsim khoom tiag tiag, kev faib tawm ntawm cov kab nrib pleb sib txawv vim muaj cov yam ntxwv xws li steel zoo, ib feem zoo, thiab kev siv tshuab kub thiab txias. Qee zaum cov kab nrib pleb twb tshwm sim ua ntej kev kho cua sov thiab nthuav dav ntxiv thaum lub sij hawm quenching; qee zaum ob peb hom kab nrib pleb yuav tshwm sim nyob rau tib lub sijhawm tib lub sijhawm. Nyob rau hauv cov ntaub ntawv no, raws li cov yam ntxwv morphological ntawm lub tawg, macroscopic tsom xam ntawm pob txha tawg nto, metallographic tshuaj ntsuam, thiab thaum tsim nyog, tshuaj ntsuam xyuas thiab lwm yam yuav tsum tau siv los ua ib tug kev ntsuam xyuas los ntawm cov khoom zoo, lub koom haum qauv mus rau qhov ua rau ntawm tshav kub kev kho mob kev nyuaj siab kom nrhiav tau qhov tawg. cov laj thawj tseem ceeb thiab tom qab ntawd txiav txim siab txog kev tiv thaiv zoo.
Kev tsom xam ntawm cov kab nrib pleb yog ib txoj hauv kev tseem ceeb los txheeb xyuas qhov ua rau cov kab nrib pleb. Txhua qhov tawg muaj qhov pib ntawm qhov tawg. Quenching tej kab nrib pleb feem ntau pib los ntawm convergence point ntawm radial tawg.
Yog hais tias lub hauv paus chiv keeb ntawm cov kab nrib pleb tshwm sim nyob rau saum npoo ntawm ib feem, nws txhais tau hais tias qhov tawg yog tshwm sim los ntawm lub zog tensile ntau dhau ntawm qhov chaw. Yog tias tsis muaj cov txheej txheem tsis xws luag xws li suav nrog rau ntawm qhov chaw, tab sis muaj kev ntxhov siab ntau yam xws li riam phom loj, oxide nplai, cov kaum ntse ntse ntawm cov hlau, lossis cov khoom sib hloov, cov kab nrib pleb tuaj yeem tshwm sim.
Yog hais tias lub hauv paus chiv keeb ntawm qhov tawg yog nyob rau hauv ib feem, nws muaj feem xyuam rau cov khoom tsis xws luag los yog ntau tshaj sab hauv residual tensile stress. Cov pob txha tawg ntawm ib txwm quenching yog grey thiab nplua porcelain. Yog hais tias lub pob txha tawg yog tsaus grey thiab ntxhib, nws yog tshwm sim los ntawm overheating los yog thawj cov ntaub so ntswg yog tuab.
Feem ntau hais lus, yuav tsum tsis muaj oxidation xim ntawm cov iav ntu ntawm qhov quenching tawg, thiab yuav tsum tsis muaj decarburization nyob ib ncig ntawm lub qhov tawg. Yog hais tias muaj decarburization nyob ib ncig ntawm lub tawg los yog oxidized xim nyob rau hauv lub tawg seem, nws qhia tau hais tias ib feem twb muaj cov kab nrib pleb ua ntej quenching, thiab cov thawj cov kab nrib pleb yuav nthuav nyob rau hauv lub zog ntawm kev kho cua sov kev nyuaj siab. Yog hais tias cais carbides thiab inclusions pom nyob ze ntawm cov kab nrib pleb ntawm ib feem, nws txhais tau hais tias cov kab nrib pleb muaj feem xyuam rau qhov hnyav segregation ntawm carbides nyob rau hauv raw cov ntaub ntawv los yog lub xub ntiag ntawm inclusions. Yog tias cov kab nrib pleb tsuas yog tshwm sim ntawm cov ces kaum ntse lossis cov duab hloov pauv ntawm qhov tsis muaj qhov tshwm sim saum toj no, nws txhais tau hais tias qhov tawg yog tshwm sim los ntawm cov qauv tsim tsis tsim nyog ntawm ib feem lossis kev ntsuas tsis raug los tiv thaiv cov kab nrib pleb, lossis kev kho cua sov ntau dhau.
Tsis tas li ntawd, cov kab nrib pleb hauv kev kho cua sov thiab qhov chaw quenching feem ntau tshwm nyob ze ntawm txheej tawv. Kev txhim kho cov qauv ntawm cov txheej txheem hardened thiab txo cov kev ntxhov siab ntawm kev kho cua sov yog txoj hauv kev tseem ceeb kom tsis txhob muaj cov kab nrib pleb.
Post lub sij hawm: May-22-2024