Piv nrog rau kev taw qhia lub zog tso tawm, kev xaiv laser melting tau kawm tsawg dua rau kev tsim cov ntaub ntawv ua haujlwm tau zoo, thiab tom qab- lub qhov rais ua haujlwm tseem tsis meej.
Peb cov kws tshawb fawb tau siv SLM thev naus laus zis los npaj 316L / IN718 cov ntaub ntawv ua haujlwm tau zoo thiab ntsuas qhov cuam tshuam ntawm cov neeg sawv cev kho cua sov txheej txheem ntawm theem evolution thiab tensile zog.
1.SLM npaj ntawm 316L / IN718 cov khoom ua haujlwm zoo
2. Kev kho cua sov txheej txheem
Raws li kev txheeb xyuas ntawm daim duab saum toj no, ib qho kev kho cua sov gradient tau tsim. Ob qhov kev ntsuas kub tau raug xaiv: 980℃(hauv qab qhov ntsuas kub) thiab 1040℃(siab tshaj qhov ntsuas kub), ua ke nrog ob lub tswv yim kev laus: ib qho kev laus ntawm 720℃thiab ob chav laus ntawm 720℃+ 620℃. Raws li qhov no, tsib pawg kev sim tswj tau teeb tsa:
AD pawg (lub xeev tso nyiaj): khaws cia hauv nws qhov kev npaj thawj zaug;
HT1 pawg: 1040℃kev daws teeb meem rau 1 teev (dej quenching) + 720℃ib leeg laus rau 8 teev (cua txias);
HT2 pab pawg: 1040℃kev daws teeb meem rau 1 teev (dej quenching) + 720℃laus rau 8 teev tom qab 620℃kev laus rau 8 teev (qhov cub txias);
HT3 pawg: 980℃kev daws teeb meem rau 1 teev (dej quenching) + 720℃ib leeg laus rau 8 teev (cua txias);
HT4 pab pawg: 980℃kev daws teeb meem rau 1 teev (dej quenching) + 720℃laus rau 8 teev ua raws li 620℃kev laus rau 8 teev (qhov cub txias).
3.Phase transformation tom qab kev kho cua sov
Tsib txheej ntawm X-ray diffraction (XRD) qauv nyob rau hauv Y-Z dav hlau nyob rau hauv cov kev kho cua sov sib txawv, nrog rau cov cheeb tsam xeem npog: cheeb tsam 1 (IN718 ntsiab lus 70-100%), cheeb tsam 2 (IN718 ntsiab lus 40-70%), thiab cheeb tsam 3 (IN718 ntsiab lus 0-30%).
Qhov sib txawv ntawm qhov siab tshaj plaws nyob rau hauv tsib qhov kev kho cua sov tsis qhia qhov sib txawv loj; lub Bragg xav txog ntawm lub austenitic theem-tshwj xeeb tshaj yog lub zog (111) thiab (200) peaks ntawm lub ntsej muag -centered cubic (FCC) qauv- dominated tus qauv diffraction.
Hauv HT1-cov qauv kho los ntawm cheeb tsam 1, qhov kev siv zog ntawm qhov siab tshaj (111) thiab (220) tau siab dua li ntawm lub xeev tso nyiaj (AD). Tsis tas li ntawd, tag nrho cov pab pawg kho cua sov tau pom qhov sib txawv ntawm qhov siab tshaj (311), uas qhia tau hais tias ib qho kev txhawb zog ntxiv tau tsim tom qab kev kho cua sov.
Raws li HT1 cov xwm txheej, qhov sib txawv peaks hauv cheeb tsam 2 yog dav dua thiab muaj kev siv qis dua, qhia tias theem kev ruaj ntseg hauv cheeb tsam no tsis muaj zog.
Hauv cheeb tsam 3, qhov kev siv ntawm (111) ncov hauv HT3- cov qauv kho tau zoo dua qub. Qhov tseem ceeb, 'thiab "theem ntxiv dag zog tau pom nyob rau hauv XRD qauv ntawm cheeb tsam 1. Cov cua txias ceev ceev thaum lub sij hawm high-throughput SLM npaj tsis ua rau cov nag lossis daus ntawm ' thiab " theem, thaum kho cua sov muab sij hawm txaus rau nag lossis daus ntawm cov theem ntxiv, uas piav qhia txog qhov nce ntawm qhov siv ntawm (200) thiab peak 3 (peak 3) thiab 2. tom qab kev kho cua sov.
Tom qab kev kho cua sov nrog HT2 thiab HT4, (311) diffraction peaks ntawm ' thiab " theem kuj tau kuaj pom hauv cov qauv XRD. Txawm li cas los xij, piv nrog rau (311) diffraction peaks tom qab kev daws teeb meem thiab kev laus ib leeg, qhov diffraction peaks tom qab ob chav aging tau khaus, qhia tias cov txheej txheem kev laus ob npaug ntxiv thiab ntxiv dag zog. Qhov kev siv zog ntawm lub zog ntawm theem diffraction peaks yog qhov tshwj xeeb tshaj yog nyob rau hauv HT2 kev kho mob, qhia tias qhov kev kho cua sov no txhawb cov nag lossis daus ntawm ntau dua 'thiab "theem. hloov qhov nyiam kev taw qhia ntawm 316L / IN718 cov khoom ua haujlwm tau zoo.
4.Microstructure tom qab kev kho cua sov
Nyob rau hauv cov xwm txheej depositional (AD), ntev -chain Laves theem muaj nyob rau hauv cheeb tsam 1. Vim lub siab IN718 cov ntsiab lus nyob rau hauv cheeb tsam no, ib tug loj npaum li cas ntawm Nb- nplua nuj theem precipitates nyob rau hauv lub intergranular cheeb tsam, nrog ib tug muaj pes tsawg leeg ntawm (Ni, Fe, Cr)2 (Nb, Mo, Ti). Raws li kev kho HT1, feem ntau ntawm Laves theem tau tawg thiab tawg, thiab cov seem seem hloov mus rau hauv granular morphology. Hauv kev kho HT3, Laves theem kuj hloov mus rau hauv daim ntawv granular los ntawm kev sib cais, nrog rau los ntawm nag lossis daus ntawm koob-zoo li / pas nrig-zoo li δ-Ni3Nb theem. Qhov no qhia tau hais tias ob qho tib si HT1 thiab HT3 cov qauv induced diffusion cais ntawm cov ntsiab lus (Ni, Nb, C, Mo) nyob rau hauv cheeb tsam 1, ib tug tshwm sim raws li qhov tshwm sim ntawm nyob rau hauv -situ statistical faib ntsuas ntawm hlau nyob rau hauv depositional thiab tshav kub{18}} kho cov qauv siv high{{190} microescrayut{190} spectroscopy.
Cov txiaj ntsig ntawm ntau qhov kev tshawb fawb tau lees paub tias los ntawm kev tswj hwm lub solubility ntawm Laves theem los ntawm kev daws qhov ntsuas kub thiab tswj cov morphology ntawm δ-Ni3Nb theem los ntawm lub sijhawm laus, kev ua kom zoo dua qub ntawm lub zog thiab plasticity ntawm cov ntaub ntawv gradient tuaj yeem ua tiav. Qhov no muab cov txheej txheem tseem ceeb hauv kev tsim vaj tsev rau kev txhim kho cov txheej txheem kho cua sov tshiab.
Lub microstructure evolution ntawm cheeb tsam 3 nyob rau hauv txawv kev kho cua sov regimes qhia cov theem transformation kinetics uas tau tsav los ntawm cov coupling nyhuv ntawm compositional gradient thiab thermal keeb kwm. Tus ntoo khaub lig- nplai microstructure evolution mechanism ntawm thaj av no tau sau tseg, thiab cov txheej txheem kev sib raug zoo ntawm kev kho cua sov, kab lis kev cai, thiab cov khoom siv kho tshuab tau tsim. Raws li kev tso nyiaj (AD) cov xwm txheej, 316L- cheeb tsam tseem ceeb (Cr/Ni=1.82) ua raws li ferrite-austenite (FA) dual-phase solidification txoj kev, tsim ib lub cellular dendritic qauv. Tom qab kev kho cua sov HT1, Cr / Ni piv txo qis rau 1.35. Qhov kev hloov pauv kev sib xyaw no txhawb txoj hauv kev ua kom muaj zog los ntawm ferrite-austenite dual-theem mus rau ib qho austenitic nkaus xwb- theem qauv, txo cov ntsiab lus interdendritic ferrite. Kev txheeb xyuas theem qhia txog qhov kev hloov pauv no: FCC theem yog -austenite matrix, BCC theem yog δ-ferrite, thiab Ni3Al sib raug rau 'precipitate theem. Cheeb tsam 3 yog dominated los ntawm austenite, muaj ib tug me me ntawm dispersed ferrite. Qhov ntim feem ntawm ferrite ntsuas los ntawm kev txheeb xyuas cov duab ntau yog 3.5% (AD), 0.7% (HT1), 0.2% (HT2), 1.5% (HT3), thiab 0.8% (HT4), feem, lees paub tias cov ntsiab lus ferrite nyob rau hauv tag nrho cov cua sov- txo qis hauv xeev.
Tom qab- tso tawm qhov hluav taws kub tawm txhawb kev rov ua kom zoo li qub, ua rau cov nplej coarsening thiab txo qhov sib txawv ntawm dendrite. Lub synergistic nyhuv ntawm cov compositional gradient kuj tseem ceeb: raws txoj kev taw qhia (IN718 cov ntsiab lus nce los ntawm 0 mus rau 100 wt%), qhov txo qis hauv zos txias tus nqi induces maj mam coarsening ntawm caj npab dendrite. Cov qauv tso rau hauv cheeb tsam 3 yog tus cwj pwm los ntawm cov nplej zoo equiaxed, nrog rau cov nplej me me (~ 8.4 μm) hauv qab ntawm lub pas dej yaj vim yog laser remelting. Nyob rau hauv sib piv, cov cua sov-kho cov qauv qhia ib tug ntau npaum li cas grain loj faib, tab sis grain coarsening tshwm sim nyob rau hauv cheeb tsam 3 tom qab kev kho cua sov- qhov nruab nrab grain loj loj ntawm HT1 thiab HT3 qauv yog 10.40 μm thiab 11.64 μm, feem. Qhov coarsening no feem ntau yog los ntawm kev sib koom ua ke ntawm kev sib xyaw ua ke ntawm cov cua sov thiab cov cua txias: thaj tsam 3 yog nyob rau hauv qab ntawm cov khoom siv gradient, uas ua rau cov cua sov tsawg dua thaum lub sij hawm siab -SLM txheej txheem thiab finer pib nplej; thaum cov txheej txheem txias qeeb tom qab kev kho cua sov muab sijhawm txaus rau cov qoob loo loj hlob. Tsis tas li ntawd, cov qauv muaj cov kab nrib pleb txuas ntxiv uas nkag mus rau ntau txheej. Vim yog cov yam ntxwv ceev ceev ceev ceev ntawm cov txheej txheem SLM, cov kev loj hlob ntawm cov nplej feem ntau yog ua raws li cov kev taw qhia ntawm qhov kub siab tshaj plaws gradient (piv txwv li, perpendicular mus rau hauv qab ntawm lub pas dej molten).
Kev kho mob txo qis kev ntxhib los mos thiab txhim kho kev sib luag, nrog HT2 qhia cov txiaj ntsig tseem ceeb tshaj plaws: 1040℃kev daws teeb meem kev kho mob ua ke nrog kev laus ob zaug induces subgrain ciam teb, nce qhov feem ntawm me me -angle grain ciam teb (LAGBs) mus rau 39.1% (qhov siab tshaj plaws ntawm tag nrho cov kev kho cua sov). Qhov no zoo heev txhim kho ntau yam - nplai sib koom ua ke deformation muaj peev xwm ntawm cov qauv gradient thiab txhawb nqa tus cwj pwm isotropic.
Tom qab- kev daws teeb meem kev kho cua sov ua rau txo qis kev ntxhov siab thiab txhawb nqa kev tawg ntawm Laves theem (qhov℃ntawm kev sib cais nce monotonically nrog kev daws kub); siab -throughput SLM inherently refines lub deposited microstructure vim nws siab txias npaum li cas, tab sis tom qab cua sov kev kho mob induces tseem ceeb grain coarsening. Qhov tseem ceeb, ib qho me me ntawm δ-Ni3Nb theem tseem nyob tom qab kev daws teeb meem ntawm 980 degree, qhia tias qhov ntsuas kub no qis dua δ-Ni3Nb theem tshuaj kab.
5. Tensile zog
Tensile tawg yog yuav luag tag nrho cov concentrated nyob rau hauv lub compositional hloov cheeb tsam ntawm 30% IN718 + 70% 316L thiab 40% IN718 + 60% 316L cheeb tsam, qhov twg elemental segregation tau tshaj tawm. Qhov kev zam tsuas yog tshwm sim hauv HT2 tshav kub-kho lub xeev, qhov chaw tawg pib ntawm 50% 316L + 50% IN718 cheeb tsam thiab tau nrog lub caj dab tseem ceeb. Cov kev tshawb pom no qhia tau hais tias muaj ntau qhov sib txawv ntawm qhov sib txawv ntawm qhov sib txawv ntawm cov khoom thauj -cov kabmob muaj peev xwm ntawm 316L / IN718 cov ntaub ntawv ua haujlwm tau zoo (FGMs).
Thaum cov tshuaj kub yog 1040 degree, ob qho tib si lub zog thiab plasticity ntawm cov khoom yog txhim kho. Nyob rau hauv ib qho kev laus kev kho mob, cov txheej txheem HT1 tau txhim kho lub zog ntawm 316L / IN718 cov ntaub ntawv ua haujlwm zoo (FGMs) zoo dua li HT2, nrog rau kev txhawb zog ntawm 6.58%. Cov qauv kho nrog HT2 pom qhov tseem ceeb tshaj plaws hauv elongation ntawm 1040℃tov kub, nrog nce ntawm kwv yees li 62.99%.Cov txiaj ntsig no qhia tau hais tias ntawm qhov kub ntawm 1040℃kev daws teeb meem, kev laus ib leeg yog qhov tsim nyog rau kev txhim kho lub zog, thaum ob chav laus yog qhov zoo rau kev txhim kho plasticity.
Thaum cov tshuaj kho kub poob mus rau 980 degree, cov khoom siv zog nce (ntau dua nrog kev laus dua ob zaug thiab zoo dua nrog kev laus ib leeg), tab sis cov yas qis dua piv rau lub xeev deposited.Kev txhim kho ua ke ntawm lub zog thiab plasticity qhia tias HT2 yog qhov kev kho cua sov zoo rau 316L / IN718 cov ntaub ntawv ua haujlwm zoo.
6.nyob rau hauv xaus
(1) Kev daws qhov kub thiab txias dominates theem evolution txoj kev, thaum cov nyhuv ntawm kev laus yog negligible. Kev daws qhov kub thiab txias siab dua los yog sib npaug ntawm 1040℃tuaj yeem ua rau cov theem Laves thiab inhibit qhov tsim ntawm δ-Ni3Nb theem, yog li tso Nb cov ntsiab lus rau cov nag lossis daus tom qab ntawm ″ / ′, muab qhov tsim nyog ua ntej kom tau txais qhov sib npaug zoo ntawm lub zog thiab plasticity.
(2) Kev laus txoj kev tso cai rau lub zog -plasticity tswj. Kev laus ob npaug tom qab kev daws teeb meem ntawm 1040℃tuaj yeem nce plasticity li ntawm 30% yam tsis muaj kev txi lub zog, ua rau nws tsim nyog rau siab - daim ntaub ntawv plasticity. Hloov pauv, kev daws teeb meem ntawm 980℃induces nag lossis daus ntawm koob-zoo li δ-Ni3Nb theem raws li cov ciam teb; qhov no ua rau muaj qhov txo qis hauv plasticity nyob rau hauv ob qho tib si thiab ob qho kev laus, thiab yog li ntawd tsuas yog pom zoo rau cov ntawv thov qhov nruab nrab{11}} qhov kub thiab txias yog qhov tseem ceeb.
(3) Gradient Cheebtsam yuav tsum muaj "siab-kub homogenization ua raws li qis-kub laus" lub tswv yim. IN718 enriched cheeb tsam nws tus kheej yog nplua nuj nyob rau hauv Nb thiab Mo cov ntsiab lus, yuav tsum tau ua ntej - kev daws teeb meem ntawm ntau dua los yog sib npaug rau 1040℃; txwv tsis pub, tom qab qis - kub aging yuav tsim ib rab koob txuas ntxiv -zoo li δ-Ni3Nb theem network, ua rau hauv chav tsev- kub toughness poob ntau dua lossis sib npaug li 40%. Txoj kev kho no tuaj yeem ua tus qauv tsim qauv rau kev kho cua sov tom qab xaiv laser melting (SLM) ntawm cov khoom zoo sib xws (FGMs).
(4) Cov yam ntxwv ntawm cov ntaub ntawv gradient yuav tsum ua raws li peb -theem kaw- txheej txheem voj: Ua ntej, macroscopic tensile pre- kev tshuaj xyuas yog ua los txheeb xyuas cov khoom sib txawv ntawm - rau -batch sib txawv; thib ob, strain field distribution maps ε(x) yog plotted siv tag nrho -field digital image correlation (DIC) technology, and local stress-strain (σ-ε) constitutive kev sib raug zoo yog tau los ntawm micro/nano-scale mechanical testing; Thaum kawg, gradient constitutive qauv embedded nrog finite element tsom xam (FEA) yog calibrated. Cov kab ntawv pov thawj no tuaj yeem txiav txim siab tag nrho cov lus teb rau hauv qhov kev daws teeb meem tsim qauv tsim nyog, yog li ua kom zoo - kho cov txheej txheem thiab kev ntsuas kev ntseeg tau ntawm kev pabcuam.
