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Nzira itsva yakavakirwa pakunyungudutsa kwelaser yakasarudzwa kuti itonge chimiro chezvigadzirwa mukugadzirwa kwayo iri kukurudzirwa. Nzira iyi inoenderana nekugadzirwa kwemafungu emagetsi emagetsi akasimba mudziva rakanyungudutswa nemwaranzi yemagetsi yakaoma. Zvidzidzo zvekuedza uye simulations dzenhamba zvinoratidza kuti nzira iyi yekudzora inogoneka uye inogona kubatanidzwa zvinobudirira mukugadzirwa kwemichina yemazuva ano yekunyungudutsa yelaser yakasarudzwa.
Kugadzira zvinhu zvinowedzerwa (AM) zvezvikamu zvine chimiro chakaomarara kwakawedzera zvakanyanya mumakumi emakore achangopfuura. Zvisinei, pasinei nekusiyana kwemaitiro ekugadzira zvinhu zvinowedzerwa, kusanganisira selective laser melting (SLM)1,2,3, direct laser metal deposition4,5,6, electron beam melting7,8 nezvimwe9,10, Zvikamu zvinogona kunge zvisina kunaka. Izvi zvinonyanya kukonzerwa nehunhu hwakananga hwe molten pool solidification process hune chekuita ne high thermal gradients, high cooling rates, uye kuoma kwe heating cycles mu melting and remelting materials11, izvo zvinotungamira ku epitaxial grain growth uye significant porosity12,13. Mhedzisiro yacho inoratidza kuti , zvakakosha kudzora thermal gradients, cooling rates, uye alloy composition, kana kuisa mamwe ma physical shocks kuburikidza ne external fields yemhando dzakasiyana (semuenzaniso, ultrasound) kuti uwane fine equiaxed grain structures.
Mabhuku akawanda ane chekuita nemhedzisiro yekurapwa kwevibration pamaitiro ekusimba mumaitiro ekugadzira echinyakare14,15. Zvisinei, kushandisa munda wekunze pakunyunguduka kwehuwandu hakuburitse chimiro chechinhu chinodiwa. Kana huwandu hwechikamu chemvura huri hudiki, mamiriro acho anochinja zvakanyanya. Muchiitiko ichi, munda wekunze unokanganisa zvakanyanya maitiro ekusimba. Mhedzisiro yemagetsi yakafungwa panguva yeminda yakasimba yeacoustic16,17,18,19,20,21,22,23,24,25,26,27, arc stirging28 uye oscillation29, pulsed plasma arcs30,31 nedzimwe nzira32. Batanidza kune substrate uchishandisa sosi yekunze ye ultrasound ine simba (pa20 kHz). Kugadziriswa kwezviyo kunokonzerwa ne ultrasound kunokonzerwa nekuwedzera kwenzvimbo yekutonhora kwe compositional nekuda kwekudzikira kwe gradient yekushisa uye ultrasound enhancement kugadzira makristaro matsva kuburikidza ne cavitation.
Mubasa iri, takaongorora mukana wekuchinja chimiro chezviyo zvesimbi dzisina kusimba dze austenitic nekuisa sounding mudziva rakanyungudutswa nemafungu eruzha anogadzirwa ne laser inonyunguduka pachayo. Kuchinja kwesimba kwechiitiko chemwaranzi ye laser pane light-absorbing medium kunoita kuti pave nemafungu e ultrasonic, ayo anochinja microstructure yezvinhu. Uku kuchinja kwesimba kwemwaranzi ye laser kunogona kubatanidzwa zviri nyore mumaprinta eSLM 3D aripo. Kuedza mubasa iri kwakaitwa pamaplate esimbi asina kusimba ayo pamusoro pawo paive nemwaranzi ye laser inogadziriswa. Saka, tekinoroji, kurapwa kwepamusoro pe laser kunoitwa. Zvisinei, kana kurapwa kwakadaro kwe laser kukaitwa pamusoro pechikamu chimwe nechimwe, panguva yekuunganidza layer-by-layer, mhedzisiro pahuwandu hwese kana pazvikamu zvakasarudzwa zvevhoriyamu inowanikwa. Nemamwe mazwi, kana chikamu chakavakwa layer-by-layer, kurapwa kwepamusoro pelayer kwechikamu chimwe nechimwe kwakaenzana ne "kurapwa kwehuwandu hwe laser".
Kunyange zvazvo mukurapa kwe ultrasonic kwakavakirwa pa ultrasound, simba re ultrasonic re sound wave rinopararira muchikamu chose, nepo simba re ultrasonic rinokonzerwa ne laser rakanyanya kuunganidzwa pedyo nenzvimbo inonyudzwa ne laser radiation. Kushandisa sonotrode mumuchina weSLM powder bed fusion kwakaoma nekuti pamusoro pemubhedha we powder wakaratidzwa ne laser radiation inofanira kuramba yakamira. Pamusoro pezvo, hapana kushushikana kwe mechanical pamusoro pechikamu. Nokudaro, acoustic stress iri pedyo ne zero uye particle velocity ine amplitude yepamusoro pamusoro pechikamu chose. Kumanikidzwa kweruzha mukati medziva rese rakanyungudutswa hakugone kudarika 0.1% yekumanikidzwa kwepamusoro kunokonzerwa ne welding head, nekuti wavelength yema ultrasonic waves ane frequency ye 20 kHz mu stainless steel ndeye \(\sim 0.3~\text {m}\), uye kudzika kwacho kunowanzova kushoma pane \(\sim 0.3~\text {mm}\). Nokudaro, mhedzisiro ye ultrasound pa cavitation inogona kunge iri diki.
Zvinofanira kucherechedzwa kuti kushandiswa kwemwaranzi yelaser inogadziriswa nesimba mukuiswa kwesimbi yelaser zvakananga inzvimbo inoshanda yekutsvagisa35,36,37,38.
Mhedzisiro yekupisa yemwaranzi yelaser pachinhu ichi ndiyo hwaro hwenzira dzese dzelaser 39, 40 dzekugadzirisa zvinhu, dzakadai sekucheka41, kusveta, kuomesa, kuboora42, kuchenesa pamusoro, kuisa pamusoro, kupukuta pamusoro43, nezvimwewo. Kugadzirwa kwelaser kwakakurudzira budiriro itsva muhunyanzvi hwekugadzirisa zvinhu, uye mhedzisiro yekutanga yakapfupikiswa muongororo dzakawanda uye monographs44, 45, 46.
Zvinofanira kucherechedzwa kuti chero chiito chisina kumira panzvimbo iyi, kusanganisira chiito chenguva pfupi pane chinonyudza, chinoguma nekukwezvwa kwemafungu enzwi ari mairi nekushanda kwakaringana kana kushoma. Pakutanga, chinangwa chikuru chaive pakushandiswa kwemafungu nelaser muzvinwiwa uye nzira dzakasiyana-siyana dzekupisa dzinoshandiswa pakuita ruzha (kuwedzera kupisa, kubuda kwemvura, kuchinja kwevhoriyamu panguva yekuchinja kwechikamu, kukwezvwa, nezvimwewo) 47, 48, 49. Mamonograph akawanda 50, 51, 52 anopa ongororo dzedzidziso dzemaitiro aya uye mashandisirwo awo anogona kuitwa.
Nyaya idzi dzakazokurukurwa pamisangano yakasiyana-siyana, uye kukwezvwa kwe ultrasound ne laser kunoshandiswa mukushandiswa kwe tekinoroji ye laser53 nemushonga54. Nokudaro, zvinogona kutariswa kuti pfungwa huru yemaitiro ayo pulsed laser light inoshanda pachinhu chinonyudza yavepo. Kuongororwa kwe ultrasonic ne laser kunoshandiswa kuona zvikanganiso zve SLM-manufactured samples55,56.
Mhedzisiro yemafungu emagetsi anokonzerwa nelaser pazvinhu ndiyo hwaro hwe laser shock peening57,58,59, iyo inoshandiswawo pakurapa pamusoro pezvikamu zvakagadzirwa nekuwedzera60. Zvisinei, kusimbisa laser shock kunonyanya kushanda pa nanosecond laser pulses uye pamusoro pezvinhu zvakaiswa nemechanically (semuenzaniso, ne layer ye liquid)59 nekuti mechanic loading inowedzera peak pressure.
Kuedza kwakaitwa kuti kuongorore migumisiro inogona kuitika yeminda yakasiyana-siyana yemuviri pa microstructure yezvinhu zvakasimba. Dhayagiramu inoshanda yegadziriro yekuedza inoratidzwa muMufananidzo 1. Laser yakasimba yeNd:YAG inoshanda mu free-running mode (pulse duration \(\tau _L \sim 150~\upmu \text {s}\ )) yakashandiswa. Laser pulse yega yega inopfuudzwa kuburikidza neakatevedzana emafirita e neutral density uye beam splitter plate system. Zvichienderana nekusanganiswa kwemafirita e neutral density, simba re pulse pachinangwa rinosiyana kubva \(E_L \sim 20~\text {mJ}\) kusvika \(E_L \sim 100~\text {mJ}\) . Beam relaser rinoratidzwa kubva ku beam splitter rinopihwa ku photodiode kuti riwane data panguva imwe chete, uye ma calorimeter maviri (photodiodes ane nguva refu yekupindura inodarika \(1~\text {ms}\)) anoshandiswa kuona chiitiko uye chinoratidzwa kubva pachinangwa, uye ma power metres maviri (photodiodes ane mhinduro pfupi). times\(<10~\text {ns}\)) kuti vaone chiitiko uye simba re optical rakaratidzwa. Macaloriemeters nema power meters akaongororwa kuti ape ma values ​​​​mu absolute units achishandisa thermopile detector Gentec-EO XLP12-3S-H2-D0 uye dielectric mirror yakaiswa panzvimbo yemuenzaniso. Isa beam pachinangwa uchishandisa lens (Antireflection coating pa \(1.06 \upmu \text {m}\), focal length \(160~\text {mm}\)) uye beam waist panzvimbo yechinangwa 60– \(100~\upmu\text {m}\).
Dhayagiramu inoshanda yehurongwa hwekuedza: 1—laser; 2—laser beam; 3—neutral density filter; 4—photodiode yakawiriraniswa; 5—beam splitter; 6—diaphragm; 7—calorimeter yeincident beam; 8 – calorimeter yereflective beam; 9 – incident beam power meter; 10 – reflective beam power meter; 11 – focusing lens; 12 – girazi; 13 – sampuro; 14 – broadband piezoelectric transducer; 15 – 2D converter; 16 – positioning microcontroller; 17 – synchronization unit; 18 – multi-channel digital acquisition system ine siyana siyana dzesampling rates; 19 – personal computer.
Kurapa kweUltrasonic kunoitwa seizvi. Laser inoshanda mu free-running mode; saka nguva ye laser pulse i \(\tau _L \sim 150~\upmu \text {s}\), iyo ine nguva dzakawanda dzeinenge \(1.5~\upmu \text {s} \) imwe neimwe. Chimiro chenguva che laser pulse uye spectrum yayo ine envelopu ine low-frequency uye high-frequency modulation, ine avhareji yeinenge \(0.7~\text {MHz}\), sezvakaratidzwa muMufananidzo 2.- Envelopu ye frequency inopa kupisa uye kunyunguduka uye evaporation inotevera yezvinhu, nepo chikamu che high frequency chichipa vibration ye ultrasonic nekuda kwe photoacoustic effect. Mafambiro e ultrasonic pulse anogadzirwa ne laser anonyanya kutsanangurwa nechimiro chenguva che laser pulse intensity. Kubva pa \(7~\text {kHz}\) kusvika pa \ (2~\text {MHz}\), uye frequency yepakati ndeye \(~ 0.7~\text {MHz}\). Mapundu enzwi nekuda kwemhedzisiro ye photoacoustic akarekodhwa achishandisa ma transducer e broadband piezoelectric akagadzirwa nema polyvinylidene fluoride films. Ma waveform akarekodhwa uye spectrum yawo zvinoratidzwa muMufananidzo 2. Zvinofanira kucherechedzwa kuti chimiro chemapundu ezwi chinowanzoonekwa ne laser ye free-running mode.
Kupararira kwenguva pfupi kwesimba rekurova kwemoyo kwelaser (a) uye kumhanya kweruzha kumashure kwemuenzaniso (b), maspectra ekurova kwemoyo kwelaser (c) uye kurova kwemoyo kweultrasonic (d) kwaive neavhareji yekurova kwemoyo kwelaser kunopfuura mazana matatu (red curve) kwekurova kwemoyo kwelaser imwe chete (blue curve).
Tinogona kusiyanisa zvakajeka zvikamu zve low-frequency ne high-frequency zve acoustic treatment zvinoenderana ne low-frequency envelope ye laser pulse uye high-frequency modulation, zvichiteerana. Ma wavelength ema acoustic waves anogadzirwa ne laser pulse envelope anopfuura \(40~\text {cm}\); saka, mhedzisiro huru ye broadband high-frequency components ye acoustic signal pa microstructure inotarisirwa.
Maitiro emuviri muSLM akaoma uye anoitika panguva imwe chete pazviyero zvakasiyana zvenzvimbo nenguva. Nokudaro, nzira dzemhando dzakasiyana-siyana dzakakodzera zvakanyanya pakuongorora dzidziso yeSLM. Mamodheru emasvomhu anofanira kutanga aine akawanda-simba. Maitiro uye thermophysics ye "solid-liquid medium" inonyunguduka nemhepo isina gasi inogona kutsanangurwa zvinobudirira. Hunhu hwezvinhu zvinopisa muSLM ndeinotevera.
Kupisa nekutonhodza zvinosvika \(10^6~\text {K}/\text {s}\) /\text{ nekuda kwekushandiswa kwemwaranzi yelaser munzvimbo ine simba rakawanda kusvika \(10^{13}~\text {W} cm}^2\).
Kutenderera kwekunyunguduka-kusimba kunogara pakati pe1 ne \(10~\text {ms}\), izvo zvinobatsira kuti nzvimbo yekunyunguduka isimbiswe nekukurumidza panguva yekutonhodza.
Kupisa nekukurumidza kwenzvimbo yemuenzaniso kunoguma nekuumbwa kwekumanikidzwa kwakanyanya kwethermoelastic muchikamu chepamusoro. Chikamu chakakwana (kusvika 20%) chechikamu cheupfu chinopwanyika zvakanyanya63, izvo zvinoguma nekumanikidzwa kwakawedzerwa pamusoro nekuda kwekubvisa kwelaser. Nekuda kweizvozvo, kumanikidzwa kwakakonzerwa kunokanganisa zvakanyanya geometry yechikamu, kunyanya pedyo nekutsigira uye zvinhu zvitete zvechimiro. Kupisa kwakanyanya mu pulsed laser annealing kunoguma nekugadzirwa kwemafungu e ultrasonic strain anopararira kubva pamusoro kuenda ku substrate. Kuti uwane data rakarurama rehuwandu pamusoro pekumanikidzwa kwenzvimbo uye kugoverwa kwe strain, kuenzaniswa kwe mesoscopic kwedambudziko re elastic deformation rakabatana nekupisa uye kutamiswa kwehuwandu kunoitwa.
Maequations anotonga emuenzaniso anosanganisira (1) maequations ekuchinjana kupisa asina kugadzikana apo thermal conductivity inoenderana nemamiriro echikamu (hupfu, kunyunguduka, polycrystalline) uye tembiricha, (2) kuchinja-chinja kwe elastic deformation mushure mekubviswa kwe continuum uye thermoelastic expansion equation. Dambudziko remuganhu rinotsanangurwa nemamiriro ekuyedza. Modulated laser flux inotsanangurwa pamusoro pemuenzaniso. Convective cooling inosanganisira conductive heat exchange uye evaporative flux. Mass flux inotsanangurwa zvichibva pakuverenga kwe saturated vapor pressure yezvinhu zvinobuda. Hukama hwe elastoplastic stress-strain hunoshandiswa apo thermoelastic stress inoenderana nemusiyano wetembiricha. Kune nominal power \(300~\text {W}\), frequency \(10^5~\text {Hz}\), intermittent coefficient 100 uye \(200~\upmu \text {m}\ ) ye effective beam diameter.
Mufananidzo 3 unoratidza mhedzisiro yekuenzanisa nhamba yenzvimbo yakanyungudutswa uchishandisa modhi yemasvomhu ye macroscopic. Dhayamita yenzvimbo yekubatanidza i \(200~\upmu \text {m}\) (\(100~\upmu \text {m}\) radius) uye \(40~\upmu \text {m}\) kudzika. Mhedzisiro yekuenzanisa inoratidza kuti tembiricha yepamusoro inosiyana munharaunda nenguva se \(100~\text {K}\) nekuda kwekuwedzera kwekuchinja kwepulse. Kupisa \(V_h\) uye kutonhora \(V_c\) mwero uri pa \(10^7\) uye \(10^6~\text {K}/\text {s}\), zvichiteerana. Aya mavalues ​​​​anowirirana zvakanaka neongororo yedu yapfuura64. Musiyano wehukuru pakati pe \(V_h\) uye \(V_c\) unoguma nekunyanyisa kupisa pamusoro penzvimbo, uko thermal conduction kuenda ku substrate isingakwani kubvisa kupisa.Naizvozvo, pa \(t=26~\upmu \text {s}\) tembiricha yepamusoro inosvika \(4800~\text {K}\). Kubuda kwemvura nesimba kwezvinhu zvinogona kukonzera kuti pamusoro pemuenzaniso pave nekumanikidzwa kwakanyanya uye kubvaruka.
Mhedzisiro yekuenzanisa nhamba yenzvimbo yekunyunguduka kwe single laser pulse annealing paplate yemuenzaniso ye316L. Nguva kubva pakutanga kwepulse kusvika pakadzika pedziva rakanyungudutswa inosvika pakakwirira i \(180~\upmu\text {s}\). Isotherm\(T = T_L = 1723~\text {K}\) inomiririra muganho uri pakati pezvikamu zvemvura nezvakasimba. Isobars (mitsara yeyero) inoenderana nekushushikana kweiyoeld kwakaverengerwa sebasa rekupisa muchikamu chinotevera. Nokudaro, munharaunda iri pakati pezvikamu zviviri (isotherms\(T=T_L\) uye isobars\(\sigma =\sigma _V(T)\)), chikamu chakasimba chinoiswa pasi pemitoro yakasimba yemakanika, izvo zvinogona kutungamira kuchinjwa kwe microstructure.
Mhedzisiro iyi inotsanangurwa zvakare muMufananidzo 4a, apo mwero wekumanikidzwa munzvimbo yakanyungudutswa unorongedzwa senzira yenguva uye daro kubva pamusoro. Chekutanga, maitiro ekumanikidzwa ane chekuita nekuchinja kwesimba rekurova kwemhepo kwelaser kunotsanangurwa muMufananidzo 2 pamusoro. Kumanikidzwa kukuru \text{s}\) kweinenge \(10~\text {MPa}\) kwakaonekwa painenge \(t=26~\upmu). Chechipiri, kuchinja kwekumanikidzwa kwenzvimbo panzvimbo yekudzora kune hunhu hwakafanana nekufamba kwenguva kwe \(500~\text {kHz}\). Izvi zvinoreva kuti mafungu ekumanikidzwa e ultrasonic anogadzirwa pamusoro uye obva apararira mu substrate.
Hunhu hwakaverengerwa hwenzvimbo yekuchinja kwechinhu iri pedyo nenzvimbo yekunyunguduka hunoratidzwa muMufananidzo 4b. Kubviswa kweLaser uye kumanikidzwa kwethermoelastic zvinogadzira mafungu e elastic deformation anopararira mu substrate.Sezvinogona kuonekwa kubva pamufananidzo, kune matanho maviri ekugadzira kushushikana. Munguva yekutanga ye \(t < 40~\upmu \text {s}\), kushushikana kweMises kunokwira kusvika ku \(8~\text {MPa}\) ne modulation yakafanana nekumanikidzwa kwepamusoro. Kushushikana uku kunoitika nekuda kwekubvisa kwelaser, uye hapana kushushikana kwethermoelastic kwakaonekwa munzvimbo dzekudzora nekuti nzvimbo yekutanga yakabatwa nekupisa yaive diki kwazvo. Kana kupisa kwapararira mu substrate, nzvimbo yekudzora inogadzira kushushikana kwakanyanya kwethermoelastic pamusoro pe \(40~\text {MPa}\).
Mazinga ekumanikidzwa akawanikwa ane simba guru pa solid-liquid interface uye anogona kunge ari iwo maitiro ekudzora anotungamira nzira yekusimba. Hukuru hwenzvimbo yekusimba hwakakura ka2 kusvika katatu kupfuura iyo yenzvimbo yekunyunguduka.Sezvinoratidzwa muMufananidzo 3, nzvimbo yeisotherm yekunyunguduka uye huwandu hwekumanikidzwa hwakaenzana nekusimba kwemhedzisiro zvinoenzaniswa. Izvi zvinoreva kuti pulsed laser irradiation inopa mitoro yakawanda yemakanika munzvimbo dziri munzvimbo dzine dhayamita inoshanda pakati pe300 ne \(800~\upmu \text {m}\) zvichienderana nenguva inokurumidza.
Saka, kugadziriswa kwakaoma kwe pulsed laser annealing kunotungamira kumhedzisiro ye ultrasonic. Nzira yekusarudza microstructure yakasiyana kana ichienzaniswa ne SLM isina ultrasonic loading. Nzvimbo dzisina kugadzikana dzakagadziriswa dzinotungamira kumatanho enguva nenguva ekudzvanywa nekutatamuka muchikamu chakasimba. Saka, kuumbwa kwemiganhu mitsva yezviyo nemiganhu yepasi pegorosi kunova kunogoneka. Nokudaro, hunhu hwe microstructural hunogona kuchinjwa nemaune, sezvakaratidzwa pazasi. Mhedziso dzakawanikwa dzinopa mukana wekugadzira pulse modulation-induced ultrasound-driven SLM prototype. Muchiitiko ichi, piezoelectric inductor 26 inoshandiswa kune dzimwe nzvimbo inogona kubviswa.
(a) Kumanikidzwa sebasa renguva, kwakaverengwa padaro rakasiyana kubva pamusoro 0, 20 uye \(40~\upmu \text {m}\) pamwe chete ne axis ye symmetry.(b) Kumanikidzwa kweVon Mises kunoenderana nenguva kwakaverengwa mu solid matrix padaro 70, 120 uye \(170~\upmu \text {m}\) kubva pamusoro wemuenzaniso.
Kuedza kwakaitwa pamaplate esimbi asina ngura eAISI 321H ane saizi \(20\times 20\times 5~\text {mm}\). Mushure mekurova kwega kwega kwelaser, ndiro inofamba \(50~\upmu \text {m}\), uye chiuno chelaser beam chiri pamusoro pechinangwa chingangoita \(100~\upmu \text {m}\). Kusvika kushanu kunotevera kwebeam kunoitwa nenzira imwecheteyo kuti zvinhu zvakagadziriswa zvinyungudutswe kuti zvinatswe. Muzviitiko zvese, nzvimbo yakanyungudutswa yakaitwa sonicated, zvichienderana nechikamu che oscillatory chemwaranzi yelaser. Izvi zvinoguma nekuderedzwa kweavhareji yenzvimbo yebean kanopfuura ka5. Mufananidzo 5 unoratidza kuti chimiro che microstructure chenzvimbo yakanyungudutswa nelaser chinochinja sei nehuwandu hwematanho anotevera ekudzokorora (passes).
Mapuranga madiki (a,d,g,j) uye (b,e,h,k) – magadzirirwo enzvimbo dzakanyungudutswa nelaser, mapuranga madiki (c,f,i,l) – kugoverwa kwenzvimbo dzetsanga dzine mavara. Mumvuri unomiririra zvidimbu zvinoshandiswa kuverenga histogram. Mavara anoenderana nenzvimbo dzetsanga (ona bhaa remavara riri pamusoro pehistogram. Mapuranga madiki (ac) anoenderana nesimbi isina tsvina isina kugadziriswa, uye mapuranga madiki (df), (gi), (jl) anoenderana ne1, 3 uye 5 remelts.
Sezvo simba rekupisa kwelaser risingachinje pakati pemapasi anotevera, kudzika kwenzvimbo yakanyungudutswa kwakafanana. Saka, nzira inotevera "inofukidza" zvachose yekare. Zvisinei, histogram inoratidza kuti nzvimbo yepakati nepakati yetsanga inoderera nekuwedzera kwehuwandu hwemapasi. Izvi zvinogona kuratidza kuti laser iri kushanda pane substrate kwete pane yakanyunguduka.
Kugadziriswa kwezviyo kunogona kukonzerwa nekutonhora nekukurumidza kwedziva rakanyungudutswa65. Kumwe kuyedza kwakaitwa umo pamusoro pemaplate esimbi isina ngura (321H ne316L) akaonekwa nemwaranzi yelaser inoenderera mberi mumhepo (Mufananidzo 6) uye vacuum (Mufananidzo 7). Simba relaser (300 W ne100 W, zvichiteerana) uye kudzika kwedziva rakanyungudutswa zviri pedyo nemigumisiro yekuedza yelaser yeNd:YAG mu free-running mode. Zvisinei, chimiro che columnar chakajairika chakaonekwa.
Magadzirirwo echikamu chidiki chenzvimbo yakanyungudutswa nelaser yelaser inoenderera mberi newave (simba risingaperi re300 W, kumhanya kweskena kwe200 mm/s, simbi isingatsvedzi yeAISI 321H).
(a) Microstructure uye (b) mifananidzo ye diffraction yemaerekitironi kumashure kwenzvimbo yakanyungudutswa nelaser iri mu vacuum ine continuous wave laser (simba risingaperi re100 W, 200 mm/s scan speed, AISI 316L stainless steel)\ (\sim 2~\text {mbar}\).
Saka, zvinoratidzwa zvakajeka kuti modulation yakaoma yelaser pulse intensity ine simba guru pa microstructure inobuda. Tinotenda kuti mhedzisiro iyi ndeye mechanical uye inoitika nekuda kwekugadzirwa kwe ultrasonic vibrations inopararira kubva pamusoro wakavhenekerwa we melt yakadzika mu sample. Mhedzisiro yakafanana yakawanikwa mu 13, 26, 34, 66, 67 uchishandisa external piezoelectric transducers uye sonotrodes zvinopa high-intensity ultrasound muzvinhu zvakasiyana-siyana zvinosanganisira Ti-6Al-4V alloy 26 uye stainless steel 34 mhedzisiro. Maitiro anogona kufungidzirwa seizvi. Ultrasound yakasimba inogona kukonzera acoustic cavitation, sezvakaratidzwa mu ultrafast in situ synchrotron X-ray imaging. Kudonha kwema cavitation bubbles kunogadzira ma shock waves mu melt material, ane front pressure inosvika pa 100~\text {MPa}\)69. Ma shock waves akadaro anogona kunge akasimba zvakakwana kukurudzira kuumbwa kwe critical-sized solid-phase nuclei mu bulk liquids, zvichikanganisa typical columnar grain structure ye Kugadzira zvinhu zvinowedzerwa padanho nedanho.
Pano, tinokurudzira imwe nzira ine chekuita nekuchinja kwechimiro ne sonication yakasimba. Pakarepo mushure mekusimba, chinhu chacho chiri patembiricha yepamusoro pedyo nenzvimbo yekunyunguduka uye chine kukombama kwakaderera kwazvo. Mafungu akasimba e ultrasonic anogona kukonzera kuyerera kwepurasitiki kuchinja chimiro chezviyo zvechinhu chinopisa, chakasimba chete. Zvisinei, data rekuyedza rakavimbika pamusoro pekushandiswa kwekupisa kwekusimba kwekukohwa rinowanikwa pa \(T\lesssim 1150~\text {K}\) (ona Mufananidzo 8). Saka, kuti tiedze iyi fungidziro, takaita ma simulation e molecular dynamics (MD) e Fe-Cr-Ni composition yakafanana neAISI 316 L steel kuitira kuti tiongorore maitiro ekusimba kwekukohwa pedyo nenzvimbo yekunyunguduka. Kuti tiverenge kukombama kwekukohwa, takashandisa nzira ye MD shear stress relaxation yakatsanangurwa mu 70, 71, 72, 73. Pakuverenga kwe interatomic interaction, takashandisa Embedded Atomic Model (EAM) kubva ku 74. MD simulations dzakaitwa uchishandisa LAMMPS codes 75,76. Ruzivo rweMD simulations ruchaburitswa kune imwe nzvimbo. MD calculation results of yield Kushushikana sekushanda kwetembiricha kunoratidzwa muMufananidzo 8 pamwe chete nedata rekuyedza riripo uye kumwe kuongorora77,78,79,80,81,82.
Kushushikana kwezvibereko zvesimbi isina tsvina yeAISI giredhi 316 uye kuumbwa kwemuenzaniso zvichienderana nekupisa kwemuenzaniso weMD. Kuyerwa kwekuyedza kubva kune zvinongedzo: (a) 77, (b) 78, (c) 79, (d) 80, (e) 81. tarisa.(f)82 imhando yekuongorora yekuvimbika kwekupisa-kwezvibereko pakuyera kushushikana kwemukati panguva yekugadzira additives ne laser. Mhedzisiro yemuenzaniso weMD wakakura muchidzidzo ichi inoratidzwa se \(\vartriangleleft\) yekristaro imwe isina chikanganiso uye \(\vartriangleright\) yezviyo zvakaganhurirwa tichifunga nezvehukuru hwezviyo kuburikidza neHall-Petch relation Dimensions\(d = 50~\upmu \text {m}\).
Zvinogona kuonekwa kuti pa \(T>1500~\text {K}\) kushushikana kwegoho kunodzikira pasi pe \(40~\text {MPa}\). Kune rumwe rutivi, fungidziro dzinofanotaura kuti amplitude ye ultrasonic inogadzirwa ne laser inodarika \(40~\text {MPa}\) (ona Mufananidzo 4b), izvo zvakakwana kukonzera kuyerera kwepurasitiki muchinhu chinopisa changosimba.
Kuumbwa kwesimbi isina ngura ye12Cr18Ni10Ti (AISI 321H) inonzi austenitic stainless steel panguva yeSLM kwakaongororwa nekuyedza uchishandisa complex intensity-modulated pulsed laser source.
Kudzikira kwehukuru hwetsanga munzvimbo yekunyungudutsa kwelaser kwakawanikwa nekuda kwekunyunguduka kwelaser nguva dzose mushure mekupfuura kamwe chete, katatu kana kashanu.
Kuenzanisa kwemacroscopic kunoratidza kuti hukuru hunofungidzirwa hwenzvimbo iyo ultrasonic deformation inogona kukanganisa zvakanaka kumberi kwekusimba hunosvika \(1~\text {mm}\).
Muenzaniso weMD une microscopic unoratidza kuti simba rekugadzira simbi isina tsvina yeAISI 316 austenitic rakaderedzwa zvakanyanya kusvika pa \(40~\text {MPa}\) pedyo nenzvimbo yekunyunguduka.
Zvakawanikwa zvinoratidza nzira yekudzora magadzirirwo ezvinhu uchishandisa laser processing yakaoma uye inogona kushanda sehwaro hwekugadzira shanduko itsva dze pulsed SLM technique.
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