01
Abstract
Tungsten, vim nws qhov siab melting point, zoo thermal conductivity, thiab qis hydrogen retention, yog ib qho khoom siv zoo tshaj plaws rau cov ntshav plasma-cov khoom taw qhia nyob rau hauv nuclear fusion reactors. Txawm li cas los xij, nws cov brittleness thiab siab ductile -brittle hloov kub (DBTT) ua rau nws muaj feem cuam tshuam rau kev tawg thaum lub sij hawm laser ua. Qhov no yog qhov tseem ceeb vim qhov txias txias heev thiab kub gradient ua rau thermal stress thiab grain ciam teb tsis muaj zog. Cov txheej txheem uas twb muaj lawm los tiv thaiv kev tawg xws li substrate preheating, nanoparticle alloying, thiab pulsed lasers, tab sis cov txheej txheem no muaj kev txwv xws li hmoov degradation, kev hloov pauv, lossis nce porosity. Nyob rau hauv xyoo tas los no, laser beam shaping (xws li lub nplhaib beams) tau siv los txo lub ncov lub zog ceev, hloov qhov sib sib zog nqus nqus vuam rau hauv thermally conductive vuam, zoo txo qhov kub thiab txias gradients. Laser beam oscillation tuaj yeem do lub pas dej molten, ntxiv homogenize tshav kub input, thiab txhawb equiaxed grain tsim. Ob txoj kev yog ua raws li kev tswj hwm thermodynamic thiab muaj cov txheej txheem ntxiv. Daim ntawv no qhia txog kev sib txuas ua ke kom ua tiav qhov tawg tuaj yeem rov ua dua -vuam dawb huv ntawm tungsten yam tsis muaj preheating lossis hloov kho. Qhov cuam tshuam ntawm cov kab teeb pom kev zoo thiab oscillation tsis nyob rau ntawm cov kab nrib pleb, lub pas dej molten, thiab microstructure tau kawm tiav, muab cov ntaub ntawv siv rau kev tsim khoom ntxiv.
02
Txheej txheem cej luam
Txoj kev tshawb no tau muab piv rau qhov cuam tshuam ntawm peb lub laser beam duab-Gaussian beam, nplhaib core tis (RC 80/20), thiab annular beam- ntawm tus cwj pwm tawg ntawm ib leeg- dhau welds hauv cov ntshiab tungsten nyias daim hlau nyob rau hauv qhov sib txawv oscillation tsis. Kev sib xyaw ua ke ntawm cov thermophysical simulation, kho qhov muag microscopy tsom xam, thiab EBSD tus yam ntxwv, kev soj ntsuam ntau - teev, los ntawm cov txheeb cais macroscopic tawg thiab molten pas dej geometry mus rau microscopic grain qauv. Cov txiaj ntsig tau pom tau tias Gaussian beam, vim nws lub zog siab tshaj plaws, yooj yim tsim lub pas dej sib sib zog nqus thiab nqaim (qhov tob- rau-} dav piv> 1), ua rau tawg loj heev, nrog qhov tawg - dawb tus nqi tsuas yog 36%. Nyob rau hauv sib piv, lub annular thiab RC 80/20 kab teeb, los ntawm kev txo lub ncov hwj chim ceev, widen thiab ntiav lub molten pas dej ua ke, txo qhov kub ntawm gradient thiab txias npaum li cas. Lub RC 80/20 beam ib leeg tuaj yeem ua tiav qhov tawg - pub dawb ntawm 80%. Ua raws li lub hauv paus no, qhov sib ntxiv ntawm laser beam oscillation ntxiv suppressed cracking nyob rau hauv tag nrho cov beam hom, nrog nam piv feem ntau poob qis hauv qab 1. Kev sib xyaw ntawm RC 80/20 thiab oscillation ua tau zoo tshaj plaws, ua tiav 91% tawg- tus nqi pub dawb hla 55 qhov teeb meem. Tsis tas li ntawd, nws tau ua rau tsim cov pob zeb loj dua nyob rau hauv lub pas dej molten, zoo sib xws rau qhov simulated txias tus nqi txo mus txog 45%. Kev txheeb xyuas zaum kawg tau qhia tias cov duab ntawm lub teeb, lub zog laser, thiab kev ntsuas nrawm yog qhov tseem ceeb tshaj plaws uas cuam tshuam rau kev pib tawg, thaum oscillation zaus thiab amplitude tsis muaj qhov cuam tshuam loj hauv qhov kev tshawb fawb no. Qhov no qhia tau hais tias kev sib koom ua ke ntawm kev sib koom ua ke ntawm cov nqaj shaping thiab oscillation tuaj yeem ua tiav qhov tawg tau rov ua dua - dawb vuam ntawm tungsten yam tsis muaj preheating lossis hloov khoom siv.
03
Graphic Analysis
Cov ntaub ntawv nyob rau sab laug sab sauv ntawm daim duab 1 qhia tau hais tias, nyob rau hauv tib qhov chaw txoj kab uas hla (202 μm) thiab cov txheej txheem txheej txheem, qhov kub gradient G ntawm RC 80/20 beam yog ho qis dua li ntawm Gaussian beam, thaum qhov kev loj hlob R yog me ntsis siab dua. Qhov tseem ceeb nyob rau hauv qhov kev ntsuas qhov ntsuas cua txias tau tshwm sim nyob rau sab xis sab xis - tus nqi txias ntawm RC 80/20 beam yog txo los ntawm kwv yees li 40% piv rau Gaussian beam nrog tib txoj kab uas hla, thiab ntxiv txo los ntawm kwv yees li 45% rau cov kab hluav taws xob annular. Lub simulated molten pas dej ua ke hla- ntu hauv qab no kuj pom qhov pom qhov no: lub pas dej molten ntawm cov nqaj zoo li dav dua thiab ntiav. Cov ntaub ntawv no ncaj qha piav qhia vim li cas beam shaping tuaj yeem txo qhov kev ntxhov siab thermal zoo- ua rau cov kab nrib pleb, muab kev txhawb zog rau cov kev sim tom ntej los ntawm qhov ntsuas kub.
Daim duab 2 sib raug rau Gaussian beam. Yog tsis muaj oscillation, ib tug longitudinal tawg nkag mus rau tag nrho cov weld. Txawm li cas los xij, nrog rau qhov sib ntxiv ntawm oscillation, txawm nyob rau ntawm cov kab zoo sib xws, qhov tawg tau ploj mus. Daim duab 3 sib raug rau RC 80/20 beam. Tsis muaj oscillation, ib qho tawg tseem muaj nyob rau ntawm cov kab hluav taws xob siab ceev. Nrog rau qhov sib ntxiv ntawm oscillation, lub tawg yog kiag li tshem tawm. Qhov no qhia tau hais tias tsis hais txog ntawm lub nqaj zoo li cas, oscillation tuaj yeem cuam tshuam cov kab nrib pleb. Lub mechanism yog hais tias lub beam oscillation stirs lub molten pas dej ua ke, ua rau lub tshav kub input ntau uniform. Lub pas dej ua ke nqaim thiab sib sib zog nqus molten yog qhov dav dav, thiab qhov tob - rau- qhov dav qhov sib piv poob qis hauv qab 1. Cov vuam hom hloov los ntawm kev sib sib zog nqus vuam mus rau qhov kub thiab txias, yog li tso cov thermal stress.
Daim duab 4 qhia txog cov txiaj ntsig ntawm kev ua cov tswv yim ntawm qib microstructural. Sab laug qhia tau hais tias qhov nruab nrab grain loj ntawm Gaussian beam (93 μm) tsuas yog 10.2 μm; siv RC 80/20 ib leeg (202 μm) nce nws mus rau 14.3 μm; thiab thaum RC 80/20 ua ke nrog oscillation, cov nplej coarsen ntxiv, uas zoo kawg nkaus phim qhov kev simulation ntawm 45% txo qhov txias. Cov ntaub ntawv piv txwv ntawm sab xis qhia tau hais tias cov nplej ntawm qhov sib xyaw thiab oscillation ua ke yog ze dua rau equiaxed (qhov sib piv ze rau 1), thaum cov nplej ntawm Gaussian beam yog kom meej columnar (qhov loj dua). Ib qho kev faib ua feem ntau dua thiab ntau dua ntawm cov nplej equiaxed txhais tau hais tias cov khoom siv kho tshuab muaj ntau dua isotropic, thiab nws cov kev tiv thaiv rau kev tawg tawm yog muaj zog dua, yog li piav qhia tias vim li cas cov kab nrib pleb thiaj li muaj txiaj ntsig zoo ntawm qib microstructural.
04
Cov ntsiab lus
Txoj kev tshawb no tau lees paub tias kev sib koom ua ke ntawm cov teeb pom kev ntawm laser beam shaping thiab oscillation tuaj yeem ua tiav qhov tawg tau rov ua dua -dawb vuam ntawm tungsten ntshiab yam tsis muaj preheating lossis hloov khoom siv. Ntawm cov kev ntsuas ntsuas, RC 80/20 nplhaib core beam ua ke nrog oscillation tau txais txiaj ntsig zoo tshaj plaws, ua tiav qhov tawg - pub dawb ntawm 91%, ntau dua li 36% ntawm Gaussian beam. Qhov kev sib xyaw ua ke no muaj txiaj ntsig zoo tiv thaiv cov kab nrib pleb los ntawm kev txo qis lub zog siab ceev thiab nplawm lub pas dej ua ke, hloov txoj kev vuam mus rau hauv cov cua sov- ua vuam, txo qhov cua txias txog li 45%, thiab txhawb kev tsim cov pob zeb loj equiaxed. Beam duab, laser fais fab, thiab scanning ceev yog qhov tseem ceeb influencing tsis, thaum oscillation zaus thiab amplitude muaj me ntsis cuam tshuam. Kev tshawb fawb yav tom ntej yuav tsum tau tshawb xyuas ntxiv txog kev siv tau ntawm lub tswv yim no hauv ntau- txheej, ntau- dhau lamination thiab hauv PBF tiag tiag-LB / M manufacturing.
