Tswj lub Hardened Layer Depth thiab Txhim Kho Hnav Resistance ntawm National Standard Rail Heads
Dab tsi yog qhov zoo tagnrho qhov tob ntawm cov txheej txheem quenched ntawm lub taub hau tsheb ciav hlau ntawm lub teb chaws tus qauv rails?
Qhov zoo tshaj plaws qhov tob ntawm txheej txheej quenched ntawm lub taub hau tsheb ciav hlau ntawm lub teb chaws tus qauv rails yog15-25 hli, thiab qhov tob no tuaj yeem sib npaug qhov hnav tsis kam thiab toughness ntawm txoj kev tsheb ciav hlau. Thaum qhov tob ntawm quenched txheej yog tsawg tshaj li 15 hli, txheej hardened yog ib qho yooj yim mus hnav sai sai nyob rau hauv lub rov sib txhuam ntawm lub log thiab rail, nthuav tawm lub matrix qauv nrog zoo toughness tab sis tsis tshua muaj hardness, ua rau ib tug tseem ceeb acceleration ntawm hnav tus nqi thiab shortening cov kev pab cuam lub neej ntawm rail los ntawm ntau tshaj 30%. Thaum qhov tob ntawm quenched txheej yog ntau tshaj 25mm, lub brittleness ntawm txoj kev tsheb nqaj hlau nce, thiab nws yog ib qho yooj yim rau tawg lub tsheb ciav hlau lub taub hau nyob rau hauv qis kub ib puag ncig los yog hnyav-haul cuam tshuam, ua rau kab kev nyab xeeb xwm txheej. Rau 60kg / m rails siv hauv hnyav- txoj kev tsheb ciav hlau, qhov tob ntawm quenched txheej tuaj yeem tswj tau ntawm 20-25mm los txhim kho hnav tsis kam; rau 50kg / m rails siv nyob rau hauv dog dig-ceev railways, qhov tob ntawm quenched txheej tswj ntawm 15-20mm yuav ua tau raws li qhov yuav tsum tau siv. Kev tshawb pom ntawm quenched txheej qhov tob yuav tsum tau siv lub ntsuas qhov tsis haum ultrasonic nrog kev tshawb pom qhov tseeb ntawm ± 1mm.
Dab tsi yog cov txheej txheem tseem ceeb rau kev tswj qhov tob ntawm quenched txheej ntawm lub taub hau tsheb ciav hlau ntawm lub teb chaws tus qauv kev sib tw?
Cov txheej txheem tseem ceeb rau kev tswj qhov tob ntawm quenched txheej ntawm lub tsheb ciav hlau lub taub hau ntawm lub teb chaws tus qauv rails yog tsom rau peb qhov tseem ceeb tsis:cua sov kub, txias tus nqi thiab tuav lub sij hawm, uas yuav tsum tau precisely tswj kom ua tiav lub hom phiaj qhov tob. Cov cua sov txuas txais qhov nruab nrab zaus induction cua sov, thiab cov cua kub kub tswj ntawm 880-920℃. Qhov ntsuas kub no tuaj yeem ua kom tag nrho lub taub hau kev tsheb nqaj hlau, npaj rau quenching tom ntej. Kev kub siab heev yuav ua rau cov nplej ntxhib thiab txo cov kev tsheb ciav hlau, thaum qhov kub thiab txias tsis tuaj yeem tsim cov qauv austenite. Qhov sib txuas ua kom txias tau txais kev kub siab dej pos huab cua txias, thiab qhov cua txias yog tswj ntawm 50-80℃/ s. Tus nqi cua txias txiav txim siab qhov tob thiab hardness ntawm quenched txheej. Cov cua txias ntau dhau yuav ua rau muaj kev ntxhov siab sab hauv ntawm txoj kev tsheb ciav hlau, thaum lub caij txias txias heev yuav ua rau tsis txaus quenched txheej qhov tob. Lub sijhawm tuav yog tswj ntawm 5-8 feeb kom ntseeg tau tias qhov ntsuas kub tsis sib xws hauv lub taub hau tsheb ciav hlau thiab zam qhov tsis sib xws ntawm txheej txheej quenched los ntawm qhov kub thiab txias. Cov kev cai ntawm cov txheej txheem tsis yuav tsum tau txais ib qho kev tswj tsis siv neeg los saib xyuas qhov kub thiab txias ntawm lub sijhawm tiag tiag kom ntseeg tau tias qhov sib xws ntawm quenched txheej qhov tob.
Dab tsi yog qhov cuam tshuam ntawm microstructure ntawm lub taub hau tsheb ciav hlau quenched txheej ntawm kev hnav tsis kam ntawm txoj kev tsheb ciav hlau?
Kev cuam tshuam ntawm microstructure ntawm lub tsheb ciav hlau lub taub hau quenched txheej ntawm hnav tsis kam ntawm txoj kev tsheb ciav hlau yog qhov tseem ceeb, thiab qhov zoo tshaj plaws microstructure yognplua acicular tempered martensite + ib qho me me ntawm khaws cia austenite. Lub hardness ntawm nplua acicular tempered martensite yog siab npaum li HRC58-62, uas muaj kev hnav zoo heev, tuaj yeem tiv taus hnav thiab hnav los ntawm lub log- kev tsheb ciav hlau sib cuag, thiab nws hnav tus nqi yog 60% qis dua li ntawm pearlite qauv. Cov ntsiab lus ntawm ib qho me me ntawm cov austenite khaws cia yog tswj ntawm 5% -8%, uas tuaj yeem txhim kho lub zog ntawm cov txheej txheem quenched, txo cov kev ntxhov siab los ntawm kev cuam tshuam ntawm lub log-rail, thiab tsis txhob tawg hauv txheej txheej. Yog hais tias lub microstructure ntawm quenched txheej yog ntxhib acicular martensite, nws yog nkig thiab yooj yim rau tev tawm nyob rau hauv kev cuam tshuam load, uas ua rau pitting ntawm lub taub hau rail; Yog hais tias bainite qauv tshwm nyob rau hauv lub quenched txheej, nws hardness yog tsawg, hnav kuj yog heev txo, thiab rail sib tsoo voj voog yuav luv luv mus rau ib nrab ntawm cov thawj. Yog li ntawd, cov kev cai ntawm cov txheej txheem quenching yuav tsum tsom mus rau qhov zoo tshaj plaws microstructure los xyuas kom meej tias qhov hnav tsis kam ntawm txoj kev tsheb ciav hlau ua tau raws li tus qauv.
Dab tsi yog qhov yuav tsum tau ua rau qhov tob ntawm rail lub taub hau quenched txheej nyob rau hauv txawv kev khiav hauj lwm tej yam kev mob?
Cov kev xav tau rau qhov tob ntawm lub taub hau rail quenched txheej nyob rau hauv cov kev khiav hauj lwm sib txawv yog txawv heev, thiab cov tub ntxhais yog kom phim peb cov cim tseem ceeb:tsheb ciav hlau qag load, kev khiav hauj lwm ceev thiab txhua xyoo tag nrho dhau qhov hnyav. High- txoj kev tsheb ciav hlau ceev muaj lub tsheb ciav hlau khiav ceev thiab lub log siab - kev tsheb ciav hlau kev nyuaj siab, thiab muaj kev xav tau siab rau kev tiv thaiv kev qaug zog ntawm lub taub hau tsheb ciav hlau. Qhov tob ntawm quenched txheej yuav tsum tau tswj ntawm 20-25mm, thiab microstructure uniformity yuav tsum nruj me ntsis, thiab cov ntsiab lus austenite khaws cia yuav tsum tau tswj ntawm li 5%. Hnyav- txoj kev tsheb ciav hlau muaj lub tsheb ciav hlau loj thauj khoom thiab qhov hnyav tag nrho ib xyoos dhau los, thiab muaj qhov xav tau siab heev rau kev hnav tsis kam ntawm lub taub hau tsheb ciav hlau. Qhov tob ntawm quenched txheej yuav tsum tau tswj ntawm 22-25mm, thiab lub hardness yuav tsum mus txog saum HRC60 kom tiv taus hnyav{18}}haul cuam tshuam thiab abrasive hnav. Ordinary-speed railways muaj tsawg lub tsheb ciav hlau khiav ceev thiab qag load, thiab tsis tshua muaj ib xyoos tag nrho cov hnyav dhau. Qhov tob ntawm quenched txheej tswj ntawm 15-20mm tuaj yeem ua tau raws li qhov yuav tsum tau siv, thiab lub hardness yog tswj ntawm HRC58-60, ntsuas qhov hnav tsis kam thiab toughness. Kev tsheb ciav hlau hauv nroog tsheb ciav hlau muaj ntau zaus pib thiab nres thiab ntau lub log-rail cuam tshuam lub sijhawm. Qhov tob ntawm quenched txheej yuav tsum tau tswj ntawm 18-22mm, thiab cov ntsiab lus austenite khaws cia yuav tsim nyog nce mus rau 8% los txhim kho toughness thiab tsis txhob rail lub taub hau tawg.
Dab tsi yog cov txheej txheem kev tshawb nrhiav thiab cov qauv kev txiav txim zoo rau qhov tob ntawm txoj kev tsheb ciav hlau lub taub hau quenched txheej?
Cov txheej txheem nrhiav kom pom qhov tob ntawm txoj kev tsheb ciav hlau lub taub hau quenched txheej feem ntau suav nrogUltrasonic flaw detection method thiab metallographic microscope method, thiab kev sib xyaw ua ke ntawm ob txoj hauv kev tuaj yeem ua tiav kev tshawb pom tseeb thiab kev txiav txim siab zoo. Txoj kev kuaj xyuas qhov tsis zoo ntawm ultrasonic yog ib txoj kev kuaj tsis yog - puas tsuaj, uas yog siv lub tsheb ciav hlau tshwj xeeb qhov tsis zoo nrog qhov ntsuas zaus ntawm 5MHz. Qhov tob ntawm txheej txheej quenched yog xam los ntawm lub teeb liab ntawm ultrasonic tsis nyob rau ntawm qhov sib cuam tshuam ntawm txheej txheej quenched thiab matrix, nrog rau kev tshawb pom qhov tseeb ntawm ± 1mm, haum rau batch nrhiav tau ntawm cov kab ntau lawm thiab ntawm - chaw kuaj xyuas. Cov txheej txheem metallographic microscope yog ib txoj kev kuaj kev puas tsuaj. Nws yog ib qho tsim nyog yuav tsum tau coj mus kuaj los ntawm lub taub hau tsheb ciav hlau, thiab tom qab sib tsoo, polishing thiab corrosion, saib xyuas cov txheej txheem microstructure thiab qhov tob ntawm quenched txheej nyob rau hauv lub tshuab tsom iav nrog qhov loj ntawm 200 zaug, tsim nyog rau kev kuaj xyuas kom raug thiab kev txiav txim siab zoo. Tus qauv txiav txim zoo yog raws li TB/T 2344-2012. Qhov tob ntawm quenched txheej yuav tsum nyob rau hauv thaj tsam ntawm 15-25mm, lub hardness Ntau tshaj los yog sib npaug rau HRC58, lub microstructure yog zoo acicular tempered martensite, cov ntsiab lus austenite khaws cia tsawg dua los yog sib npaug li 8%, thiab tsis muaj coarse martensite thiab bainite qauv. Cov qauv piv txwv yog 3 rails ib batch, thiab 3 hla ntu tau kuaj pom rau txhua txoj kev tsheb ciav hlau. Yog hais tias ib qho kev sib tshuam tsis tsim nyog, yuav tsum tau ua ob qho piv txwv; yog tias nws tseem tsis tsim nyog, cov batch ntawm cov ntsia hlau yuav raug txiav txim tias tsis tsim nyog.