1. Taw qhia

Tungsten xov hlau, nrog ib tug tuab ntawm ob peb mus rau kaum ntawm micro-meter, yog plastically tsim rau hauv kauv thiab siv rau incandescent thiab tso tawm lub teeb.Kev tsim cov hlau yog ua raws li cov thev naus laus zis thev naus laus zis, piv txwv li, tungsten hmoov tau los ntawm cov txheej txheem tshuaj lom neeg tau ua tiav rau kev nias, sintering, thiab cov yas sib sau (rotary forging thiab kos duab).Nco ntsoov tias cov txheej txheem xaim winding yuav tsum ua rau cov khoom yas zoo thiab "tsis siab dhau" elasticity.Ntawm qhov tod tes, vim yog kev siv cov spirals, thiab qhov tseem ceeb tshaj plaws, qhov yuav tsum tau muaj kev tawm tsam siab, cov xov hlau recrystallized tsis haum rau kev tsim khoom, tshwj xeeb tshaj yog tias lawv muaj cov qauv coarse- grained.

Kev hloov kho cov khoom siv kho tshuab thiab cov yas ntawm cov ntaub ntawv me-tallic, tshwj xeeb, txo cov kev ua haujlwm hnyav-ening yam tsis muaj kev kho annealing yog ua tau los ntawm kev siv me-chanical kev cob qhia.Cov txheej txheem no suav nrog kev xa cov hlau rov ua dua, hloov pauv, thiab cov yas deformation tsawg.Cov teebmeem ntawm cyclic contraflexure ntawm txhua yam khoom ntawm cov hlau yog sau tseg, thiab lwm yam, hauv Bochniak thiab Mosor's [1] daim ntawv, ntawm no siv CuSn 6.5% tin bronze strips.Nws tau pom tias kev cob qhia mechanical ua rau kev ua haujlwm softening.
Hmoov tsis zoo, cov khoom siv tsis zoo ntawm tungsten xov hlau txiav txim siab hauv cov kev sim yooj yim uniaxial tensile yog qhov tsis txaus los kwv yees lawv tus cwj pwm hauv kev tsim cov khoom siv ntawm cov spirals.Cov xov hlau no, txawm hais tias muaj cov khoom zoo sib xws, feem ntau muaj qhov sib txawv ntawm qhov sib txawv ntawm qhov sib txawv rau winding.Yog li ntawd, thaum soj ntsuam cov yam ntxwv ntawm tungsten hlau, cov txiaj ntsig ntawm cov kev ntsuam xyuas hauv qab no tau pom tias muaj kev ntseeg siab dua: core hlau winding, unidirectional torsion, riam-ntug compress-sion, khoov-thiab-stretch, lossis thim rov qab banding [2] .Tsis ntev los no, ib qho kev sim tshiab thev naus laus zis tau npaj [3], uas cov xaim raug xa mus rau ib txhij torsion nrog nruj (TT test), thiab lub xeev kev ntxhov siab - hauv kev xav ntawm cov neeg sau ntawv - yog ze rau qhov uas tshwm sim hauv cov txheej txheem tsim khoom. ntawm fila-ments.Ntxiv mus, cov txiaj ntsig ntawm TT kev sim ua rau ntawm cov xov hlau tung-sten nrog cov kab sib txawv tau qhia nws lub peev xwm los cia siab tias lawv tus cwj pwm tom qab thaum cov txheej txheem thev naus laus zis [4, 5].

Lub hom phiaj ntawm txoj haujlwm uas tau hais hauv no yog los teb cov lus nug ntawm seb puas yog, thiab yog tias siv kev kho mob cycling deformation (CDT) li cas ntawm tungsten hlau los ntawm kev nruam ntau yam dabtsi yog khoov nrog txoj kev shearing [6], tuaj yeem hloov kho nws cov tshuab thiab thev naus laus zis. cov khoom tseem ceeb.

Feem ntau hais lus, lub voj voog deformation ntawm cov hlau (xws li, los ntawm kev nro thiab compression lossis ob sab dabtsi yog khoov) tuaj yeem nrog ob txoj haujlwm sib txawv.Thawj yog tus yam ntxwv rau lub deformation nrog me amplitudes thiab

cuam ​​tshuam nrog qhov hu ua qaug zog tshwm sim, uas ua rau muaj zog ua haujlwm-tawv hlau tig mus rau hauv ib qho strain-softened ua ntej nws puas tsuaj tshwm sim [7].

Qhov thib ob txheej txheem, tseem ceeb thaum lub sij hawm deformation nrog high-strain amplitudes, tsim muaj zog heterogenization ntawm yas ntws-generating shear bands.Yog li ntawd, muaj ib tug drastic fragmentation ntawm cov hlau qauv, tshwj xeeb tshaj yog, tsim ntawm nano-sized nplej, yog li, ib tug tseem ceeb nce nyob rau hauv nws cov khoom siv kho mob ntawm tus nqi ntawm workability.Xws li cov nyhuv yog tau nyob rau hauv piv txwv li, nruam repetitive corrugation thiab straightening txoj kev tsim los ntawm Huang li al.[8], uas muaj ntau yam, alternate, dhau (dov) ntawm strips ntawm "geared" thiab du rolls, los yog nyob rau hauv ib tug ntau sophisticated txoj kev, uas yog ib txoj kev ntawm nruam dabtsi yog khoov nyob rau hauv nro [9], qhov twg lub stretched sawb yog contraflexed vim yog ib tug reversible txav raws nws ntev ntawm txheej rotating yob.Ntawm chav kawm, qhov nthuav dav ntawm cov nplej kuj tuaj yeem tau txais thaum lub sijhawm monotonic deformation nrog cov kab mob loj, siv cov txheej txheem hu ua Severe Plastic Defor-mation, tshwj xeeb, txoj hauv kev ntawm Equal Channel Angular Extrusion [10] feem ntau txaus siab rau cov xwm txheej rau kev yooj yim. shear ntawm hlau.Hmoov tsis zoo, lawv tsuas yog siv rau hauv chav kuaj ntsuas thiab nws yog technically tsis tau

siv lawv kom tau txais cov cuab yeej tshwj xeeb ntawm cov hlua ntev lossis cov xov hlau.

Qee qhov kev sim kuj tau ua los ntsuas qhov cuam tshuam ntawm cyclically hloov shear siv nrog me me defor-mations ntawm lub peev xwm los qhib qhov tshwm sim qaug zog.Cov txiaj ntsig ntawm kev sim kev tshawb fawb tau ua tiav [11] ntawm strips ntawm tooj liab thiab cobalt los ntawm contraflexure nrog shearing paub tseeb hais tias saum toj no thesis.Txawm hais tias contraflexure nrog shearing txoj kev yog yooj yim yooj yim rau siv rau tiaj tus hlau qhov chaw, qhov kev thov ncaj qha rau cov xov hlau tsis muaj kev nkag siab, vim li ntawd, los ntawm kev txhais, nws tsis lav kom tau txais homo-geneous qauv, thiab yog li cov khoom zoo ib yam ntawm lub cir-cumference (nrog arbitrarily oriented radius) ntawm cov hlau.Vim li no, daim ntawv no siv cov txheej txheem tshiab tsim thiab qub ntawm CDT tsim los rau cov xov hlau nyias, raws li kev sib txuas txuas txuas ntxiv nrog kev sib tsoo.

Fig. 1 Scheme ntawm cov txheej txheem ntawm kev cob qhia mechanical ntawm cov xov hlau:1 tungsten hlau,2 coil nrog hlau mus unreel,3 system ntawm 6 rotating tuag,4 winding kauj,5 tawg hnyav, thiab6 nres (steel lub tog raj kheej nrog ib tug band ntawm tin bronze nyob ib ncig ntawm nws)

2. Kev sim

CDT ntawm tungsten hlau nrog ib txoj kab uas hla ntawm 200 μm tau ua nyob rau hauv ib tug tshwj xeeb tsim kev xeem ntaus ntawv uas nws lub tswv yim qhia nyob rau hauv daim duab 1. Unreeled hlau (1) los ntawm lub kauj.

(2) nrog txoj kab uas hla ntawm 100 hli, tau nkag mus rau hauv lub kaw lus ntawm rau qhov tuag (3), nrog lub qhov ntawm tib txoj kab uas hla ntawm cov hlau, uas yog tsau rau hauv ib qho vaj tse thiab rotating nyob ib ncig ntawm lub axis ntawm qhov ceev ntawm 1,350 rev / min.Tom qab dhau los ntawm lub cuab yeej, cov hlau tau reeled ntawm lub kauj (4) nrog ib txoj kab uas hla ntawm 100 mm tig ntawm qhov ceev ntawm 115 rev / min.Applied parameters txiav txim siab ntawm linear ceev ntawm hlau txheeb ze rau rotating tuag yog 26.8 mm / rev.

Tsim nyog tsim ntawm qhov tuag system txhais tau hais tias txhua txhua thib ob tuag revolved eccentrically (Fig. 2), thiab txhua daim ntawm cov hlau hla dhau lub rotating tuag tau raug mus tas li multilateral dabtsi yog khoov nrog shearing inducted los ntawm ironing ntawm ntug ntawm puab nto ntawm cov tuag.

Fig. 2 Schematic layout ntawm rotating tuag (labeled nrog tooj3 hauv daim duab 1)

Fig. 3 System of dies: a general view;b yam tseem ceeb:1 centric tuag,2 eccentric tuag,3 spacer rings

Unreeled hlau yog nyob rau hauv lub zog ntawm thawj zaug kev nyuaj siab vim hais tias ntawm daim ntawv thov ntawm nro, uas tsis tsuas yog tiv thaiv nws los ntawm entanglement, tab sis kuj txiav txim siab kev sib nrig sib koom tes ntawm dabtsi yog khoov thiab shearing deformation.Qhov no ua tau kom ua tiav ua tsaug rau lub nres mounted rau lub kauj nyob rau hauv daim ntawv ntawm ib tug tin bronze sawb nias los ntawm ib tug luj (tsim raws li 5 thiab 6 nyob rau hauv daim duab 1).Daim duab 3 qhia txog qhov pom ntawm cov cuab yeej kev cob qhia thaum folded, thiab txhua yam ntawm nws cov khoom.Kev cob qhia ntawm cov xov hlau tau ua nrog ob qhov hnyav sib txawv:

4.7 thiab 8.5 N, mus txog plaub kis los ntawm cov txheej txheem tuag.Axial kev nyuaj siab yog feem ntau ntawm 150 thiab 270 MPa.

Tensile xeem ntawm hlau (ob leeg nyob rau hauv thawj lub xeev thiab kev cob qhia) tau ua nyob rau hauv lub Zwick Roell xeem tshuab.Cov qauv ntsuas qhov ntev yog 100 mm thiab tensile strain rate yog

8 × 10^-3 s^-1.Hauv txhua kis, ib qho ntsuas ntsuas (rau txhua tus

ntawm cov variants) sawv cev tsawg kawg yog tsib tus qauv.

TT xeem tau ua nyob rau ntawm ib lub cuab yeej tshwj xeeb uas nws lub tswv yim qhia hauv daim duab 4 ua ntej nthuav tawm los ntawm Bochniak li al.(2010).Qhov nruab nrab ntawm cov tungsten hlau (1) nrog qhov ntev ntawm 1 m tau muab tso rau hauv qhov ntes (2), thiab tom qab ntawd nws xaus, tom qab dhau los ntawm cov ntawv qhia yob (3), thiab txuas qhov hnyav (4) ntawm 10 N txhua, tau thaiv hauv lub clamp (5).Lub rotary txav ntawm lub ntes (2) ua rau lub winding ob daim hlau

(reeled ntawm lawv tus kheej), nrog rau qhov kawg ntawm cov qauv kuaj, tau ua tiav nrog kev nce qib ntawm tensile stresses.

Qhov kev xeem tau yog tus naj npawb ntawm twists (N_T) yuav tsum tau rupture cov hlau thiab feem ntau tshwm sim nyob rau hauv pem hauv ntej ntawm lub tsim tangle, raws li qhia nyob rau hauv daim duab 5. Tsawg kawg kaum qhov kev ntsuam xyuas ib variant tau ua.Tom qab kev cob qhia, cov hlau muaj me ntsis wavy zoo li.Nws yuav tsum tau hais tias raws li cov ntaub ntawv ntawm Bochniak thiab Pieła (2007) [4] thiab Filipek (2010)

[5] Kev xeem TT yog ib txoj hauv kev yooj yim, nrawm, thiab pheej yig los txiav txim siab cov cuab yeej thev naus laus zis ntawm cov xov hlau uas npaj rau winding.

Fig. 4 Scheme of the TT test:1 kuaj kab mob,2 ntes tig los ntawm lub tshuab hluav taws xob, ua ke nrog cov ntaub ntawv twist,3 coj rolls,4hnyav,5 lub puab tsaig clamping kawg ntawm cov hlau

3. Cov txiaj ntsig

Cov nyhuv ntawm thawj zaug nro thiab tus naj npawb ntawm kev hla hauv cov txheej txheem CDT ntawm cov khoom ntawm tungsten xov hlau tau qhia hauv daim duab.6 thiab 7. Ib qho kev tawg loj ntawm cov khoom siv hluav taws xob tsis zoo ntawm cov xaim qhia txog qhov ntsuas ntawm inhomogeneity ntawm cov khoom tau los ntawm cov tshuab hmoov, thiab yog li ntawd, kev soj ntsuam ua tiav tsom mus rau qhov kev hloov pauv ntawm cov khoom kuaj thiab tsis yog ntawm lawv qhov tseem ceeb.

Kev lag luam tungsten hlau yog tus cwj pwm los ntawm qhov nruab nrab ntawm cov txiaj ntsig kev ntxhov siab (YS) sib npaug ntawm 2,026 MPa, lub zog tensile kawg (UTS) ntawm 2,294 MPa, tag nrho elongation ntawm

A≈2.6% thiab N_Tntau npaum li 28. Tsis hais txog ntawm

Qhov loj ntawm kev siv nro, CDT ua rau tsuas yog me me xwb

txo qis ntawm UTS (tsis pub tshaj 3% rau cov xaim tom qab plaub dhau), thiab YS thiabA nyob twj ywm ntawm tib theem (Fig. 6a–c thiab 7a–c).

Fig. 5 Saib ntawm tungsten hlau tom qab tawg hauv TT xeem

Daim duab 6 Qhov cuam tshuam ntawm kev cob qhia mechanical (tus lej hla n) ntawm mechanical (a–c) thiab technological (d) (txhais los ntawm N_Thauv TT xeem) cov khoom ntawm tungsten hlau;txuas tus nqi ntawm 4.7 N

CDT ib txwm ua rau muaj qhov nce ntxiv ntawm cov xov hlau twists N_T.Tshwj xeeb, rau thawj ob kis, N_Tnce mus txog ntau dua 34 rau qhov nro ntawm 4.7 N thiab yuav luag 33 rau qhov nro ntawm 8.5 N. Qhov no sawv cev rau kev nce ntawm kwv yees li 20% nrog rau kev lag luam xaim.Kev siv cov lej ntau dua ua rau muaj kev nce ntxiv hauv N_Ttsuas yog nyob rau hauv cov ntaub ntawv ntawm kev cob qhia nyob rau hauv nro ntawm 4.7 N. Cov hlau tom qab plaub kis qhia qhov nruab nrab qhov loj ntawm N_Ttshaj 37, uas, piv rau cov hlau nyob rau hauv thawj lub xeev, sawv cev rau kev nce ntawm ntau tshaj 30%.Kev cob qhia ntxiv ntawm cov xaim ntawm cov tensions siab dua yuav tsis hloov qhov loj ntawm qhov ua tiav N_Tqhov tseem ceeb (Fig. 6d thiab 7d).

4. Kev tshuaj xyuas

Cov txiaj ntsig tau pom tau hais tias txoj kev siv rau tungsten hlau CDT xyaum tsis hloov nws cov kev ntsuas qhov ntsuas tau txiav txim siab hauv kev ntsuas tensile (tsuas yog me ntsis txo qis hauv qhov kawg tensile lub zog), tab sis ua rau nws nce ntxiv.

cov cuab yeej cuab tam npaj rau kev tsim khoom;qhov no yog sawv cev los ntawm tus naj npawb ntawm twists hauv TT xeem.Qhov no ua pov thawj cov txiaj ntsig ntawm kev tshawb fawb ua ntej los ntawm Bochniak thiab Pieła (2007)

[4] hais txog qhov tsis muaj convergence ntawm qhov kev ntsuam xyuas tensile nrog cov kev coj cwj pwm ntawm cov xov hlau nyob rau hauv cov txheej txheem ntau lawm ntawm spirals.

Cov tshuaj tiv thaiv ntawm tungsten xov hlau ntawm cov txheej txheem ntawm CDT tseem ceeb nyob ntawm qhov kev thov nruj.Ntawm lub zog qis, ib qho pom qhov kev loj hlob parabolic nyob rau hauv tus naj npawb ntawm kev sib tw nrog tus naj npawb ntawm kev hla, thaum daim ntawv thov ntawm qhov tseem ceeb ntawm qhov nro ua rau (twb tom qab ob hla) kom ua tiav lub xeev ntawm saturation thiab stabilization ntawm yav tas los tau technologies. khoom (Fig. 6d thiab 7d).

Xws li cov lus teb muaj ntau haiv neeg ntawm tungsten hlau qhia qhov tseeb tias qhov loj ntawm qhov nro txiav txim siab qhov hloov pauv ntawm ob qho tib si ntawm kev ntxhov siab thiab lub xeev deformation ntawm cov khoom thiab yog li nws tus cwj pwm elastic-yas.Siv cov nro siab dua thaum lub sij hawm txheej txheem ntawm cov yas khoov hauv cov hlau hla ntawm kev ua tiav misaligned tuag ua rau lub vojvoog me me-khoov;Yog li ntawd, cov yas lim nyob rau hauv ib qho kev taw qhia perpendicular mus rau lub axis ntawm cov hlau lub luag hauj lwm rau lub mechanism ntawm shear yog loj thiab ua rau ib tug localized yas ntws nyob rau hauv lub shear bands.Ntawm qhov tod tes, tsis tshua muaj kev sib zog ua rau CDT txheej txheem ntawm cov xaim ua rau muaj kev koom tes ntau dua ntawm elastic strain (uas yog, cov yas strain yog me dua), uas ua rau muaj kev tswj hwm ntawm homo-geneous deformation.Cov xwm txheej no txawv txawv ntawm qhov tshwm sim thaum lub sij hawm ntsuas uniaxial tensile.

Nws tseem yuav tsum raug sau tseg tias CDT txhim kho cov yam ntxwv thev naus laus zis tsuas yog rau cov xov hlau uas muaj qhov zoo txaus, piv txwv li, tsis muaj qhov tsis xws luag sab hauv (pores, voids, discontinuities, micro-cracks, tsis muaj txaus continuity adhesion ntawm grain ciam teb, thiab lwm yam). .) tshwm sim los ntawm kev tsim cov hlau los ntawm hmoov metallurgy.Txwv tsis pub, qhov nce tawg ntawm tau txais tus nqi ntawm twists N_Tnrog rau kev nce ntawm tus lej ntawm kev hla qhia tau hais tias qhov sib txawv ntawm cov xaim sib sib zog nqus hauv nws ntau qhov chaw (ntawm qhov ntev) yog li kuj tseem tuaj yeem ua qhov tseem ceeb rau kev ntsuas qhov zoo ntawm cov xaim lag luam.Cov teeb meem no yuav yog qhov kev tshawb nrhiav yav tom ntej.

Fig. 7 Cov nyhuv ntawm kev cob qhia mechanical (tus lej hla n) ntawm mechanical (a–c) thiab technological (d) (txhais los ntawm N_Thauv TT xeem) cov khoom ntawm tungsten hlau;txuas qhov hnyav ntawm 8.5 N

5. Cov lus xaus

1, CDT ntawm tungsten xov hlau txhim kho lawv cov cuab yeej thev naus laus zis, raws li tau hais tseg hauv qhov torsion nrog kev ntsuas nruj los ntawm N_Tua ntej tawg.

2, Qhov nce ntawm N_Tindex los ntawm li 20% yog mus txog los ntawm ib tug xaim raug rau ob series ntawm CDT.

3, Qhov loj ntawm cov hlau nro hauv cov txheej txheem ntawm CDT muaj kev cuam tshuam loj rau nws cov cuab yeej thev naus laus zis uas tau txiav txim siab los ntawm tus nqi ntawm N_Tqhov ntsuas.Nws tus nqi siab tshaj plaws tau mus txog los ntawm cov xaim raug rau me ntsis nruj (tensile stress).

4, Kev siv ob qho tib si siab dua thiab ntau lub voj voog ntawm kev khoov ntau yam nrog shearing tsis raug cai vim nws tsuas yog ua rau kom ruaj khov rau yav dhau los tus nqi ntawm N._Tqhov ntsuas.

5, Kev txhim kho tseem ceeb ntawm cov cuab yeej thev naus laus zis ntawm CDT tungsten hlau tsis yog nrog kev hloov pauv ntawm cov khoom siv hluav taws xob tau txiav txim siab hauv kev sim tensile, lees paub qhov kev ntseeg ntawm kev siv tsis zoo ntawm qhov kev sim no kom cia siab tias yuav coj tus cwj pwm thev naus laus zis ntawm cov hlau.

Tau txais cov txiaj ntsig kev sim ua kom pom qhov tsim nyog CDT ntawm tungsten hlau rau kev tsim cov spirals.Hauv tshwj xeeb, raws li txoj hauv kev siv rau kev nce qib ntawm cov xaim ntev, cyclic, multidirectional dabtsi yog khoov nrog me ntsis strain, ua rau kom muaj kev ntxhov siab sab hauv.Vim li no, muaj kev txwv rau qhov nyiam ntawm cov hlau tawg thaum lub sij hawm tsim cov yas ntawm cov spirals.Raws li qhov tshwm sim, nws tau lees paub tias kev txo qis cov khoom pov tseg hauv kev tsim khoom ua rau nce kev ua haujlwm ntawm cov txheej txheem ntau lawm los ntawm kev tshem tawm cov khoom siv hluav taws xob qis qis hauv lub sijhawm uas, tom qab tawg cov xaim, kev nres xwm ceev yuav tsum yog "manually" qhib. los ntawm tus neeg ua haujlwm.