Qhov cuam tshuam ntawm shielding Gas Parameters ntawm Laser Vuam txheej txheem

Qhov cuam tshuam ntawm Shielding Gas Parameters ntawm Laser Vuam txheej txheem

01 Taw Qhia

Laser welding technology, due to its high energy density, low heat input, and non-contact characteristics, has become one of the core processes in modern precision manufacturing. Txawm li cas los xij, oxidation, porosity, thiab lub ntsiab poob los ntawm kev sib cuag ntawm lub pas dej ua ke thiab cov cua thaum lub sij hawm vuam txwv tsis pub cov khoom siv thiab kev pab cuam lub neej ntawm welds. Shielding gas, raws li lub hauv paus nruab nrab ntawm kev tswj cov vuam ib puag ncig, yuav tsum tau xaiv raws li nws hom, ntws tus nqi, thiab tshuab tshuab, ua ke nrog cov khoom yam ntxwv (xws li tshuaj reactivity thiab thermal conductivity) thiab phaj thickness.

Laser & Electron Beam ua

02 Hom Shielding Gas

Lub luag haujlwm tseem ceeb ntawm kev tiv thaiv roj yog cais tawm cov pa oxygen, tswj kev coj tus cwj pwm ntawm lub pas dej, thiab txhim kho lub zog sib txuas ua haujlwm. Raws li cov khoom siv tshuaj, cov khoom siv tiv thaiv tau muab faib ua cov pa roj tsis zoo (argon, helium) thiab cov pa roj carbon monoxide (nitrogen, carbon dioxide). Inert gases muaj cov tshuaj lom neeg ruaj khov thiab zoo tiv thaiv oxidation ntawm lub pas dej molten, tab sis lawv qhov sib txawv ntawm cov thermophysical cuam tshuam rau cov txiaj ntsig vuam.

Piv txwv li, argon (Ar) muaj qhov ntom ntom (1.784 kg / m³), ​​tsim cov txheej txheem ruaj khov, tab sis nws cov thermal conductivity tsawg (0.0177 W / m·K) ua kom txias txias thiab ua rau muaj kev nkag mus tob. Nyob rau hauv sib piv, helium (Nws) muaj ib tug thermal conductivity 8 lub sij hawm siab dua (0.1513 W / m·K), ua kom txias txias thiab nce nkag mus rau qhov tob, tab sis nws tsis tshua muaj ceev (0.1785 kg / m³) ua rau nws yooj yim rau khiav, yuav tsum tau ntau dua ntws los tiv thaiv.

Cov pa hluav taws xob ua haujlwm, xws li nitrogen (N₂), tuaj yeem txhim kho lub zog vuam los ntawm cov khoom siv- kev daws teeb meem hauv qee qhov xwm txheej, tab sis kev siv ntau dhau tuaj yeem ua rau qhov porosity lossis nkig theem los nag. Piv txwv li, nitrogen infiltration rau hauv lub pas dej molten thaum lub sij hawm duplex stainless hlau vuam yuav cuam tshuam cov ferrite / austenite theem tshuav nyiaj li cas, txo corrosion kuj.

[Duab: Daim duab 1. Laser vuam 304L stainless hlau, (sab saum toj) Ar tiv thaiv; (hauv qab) N₂ tiv thaiv]

Los ntawm cov txheej txheem kev xav, helium lub siab ionization zog (24.6 eV) suppresses plasma shielding, txhim kho laser zog nqus thiab nkag mus. Argon, nrog lub zog ionization qis (15.8 eV), yooj yim tsim cov huab cua hauv plasma, yuav tsum tau defocusing lossis pulse modulation kom txo kev cuam tshuam. Tsis tas li ntawd, cov roj ntsha nquag tuaj yeem ua rau muaj kev cuam tshuam nrog lub pas dej molten (piv txwv li, N₂ tsim nitrides nrog Cr hauv hlau), hloov kho qhov sib xyaw ntawm weld thiab yuav tsum tau ceev faj xaiv.

Cov khoom siv piv txwv:
- Hlau: Rau cov ntawv nyias (<3 mm), argon ensures surface smoothness, with oxidation layer thickness of only 0.5 μm on a 1.5 mm low-carbon steel weld. For thick plates (>10 hli), helium ntxiv txhim kho kev nkag mus.
- Stainless hlau: Argon tiv thaiv tiv thaiv Cr poob. Nyob rau hauv 3 hli tuab 304 stainless hlau, Cr cov ntsiab lus nyob rau hauv lub vuam ncav cuag 18.2% (ze rau 18.5% nyob rau hauv lub hauv paus hlau). Duplex stainless hlau xav tau Ar-N₂ sib tov (N₂ Tsawg dua lossis sib npaug li 5%) rau theem sib npaug. Kev tshawb fawb qhia tau hais tias nrog 8 hli tuab 2205 duplex stainless hlau, Ar-2% N₂ tuav lub ferrite / austenite piv ntawm 48:52 thiab tensile zog ntawm 780 MPa, zoo dua li ntshiab Ar (720 MPa).
- Aluminium alloys: Rau cov ntawv nyias (<3 mm), high reflectivity reduces absorption. Helium, with its high ionization energy, stabilizes plasma. In 2 mm thick 6061 aluminum alloy, helium shielding achieves 1.8 mm penetration, 25% deeper than with argon, with porosity below 1%. For thick plates (>5 mm), Nws -Ar sib tov (3: 1) sib npaug nkag mus thiab tus nqi. Piv txwv li, vuam 8 hli tuab 5083 phaj nrog cov roj sib xyaw ua tiav 6.2 hli nkag mus, 35% ntxaum dua li ntshiab Ar, thaum txo tus nqi los ntawm 20%.

Laser & Electron Beam ua

03 Kev cuam tshuam ntawm Kev Tiv Thaiv Gas Flow Rate

Lub shielding gas txaus tus nqi ncaj qha cuam tshuam rau kev pab them nqi thiab molten pas dej ua ke dynamics. Tsis txaus txaus tsis ua kom tag nrho cov huab cua cais tawm, ua rau oxidation thiab porosity. Cov dej ntws ntau dhau tuaj yeem ua rau muaj kev kub ntxhov, ua rau lub pas dej molten thiab ua rau muaj kev nyuaj siab lossis tawg. Raws li Reynolds tus naj npawb (Re=ρvD/μ), cov dej ntws ntau dua nce nrawm dua, thiab thaum Re> 2300, laminar ntws hloov mus rau turbulence, destabilizing lub pas dej molten. Yog li, qhov tseem ceeb txaus tus nqi yuav tsum tau txiav txim siab sim los yog los ntawm CFD simulation.

[Duab: Daim duab 2. Kev cuam tshuam ntawm qhov sib txawv shielding gas flow rates on welds]

Optimizing ntws yuav tsum xav txog thermal conductivity thiab phaj thickness:
- Steel and stainless steel: For thin low-carbon steel (1–2 mm), 10–15 L/min is suitable. For thicker plates (>6 hli), 18-22 L / min yuav tsum tau ua kom oxidation. Piv txwv li, nrog 6 hli tuab 316L stainless hlau, 20 L / min txhim kho HAZ hardness uniformity los ntawm 30%.
- Aluminum alloys: High thermal conductivity requires higher flow to prolong protection. In 3 mm thick 7075 aluminum alloy, 25–30 L/min minimized porosity (0.3%). For plates >10 hli, compound tshuab yog tsim nyog kom tsis txhob turbulence.

Laser & Electron Beam ua

04 Kev cuam tshuam ntawm Kev Tiv Thaiv Gas Tshuab Txoj Kev

Txoj kev tshuab tshuab, los ntawm kev tswj cov airflow kev taw qhia thiab kev faib tawm, ncaj qha cuam tshuam rau lub pas dej molten ntws thiab kev cuam tshuam tsis zoo. Nws hloov qhov nro gradients thiab Marangoni ntws, yog li tswj molten pas dej ua ke dynamics. Sab-blowing induces directional flow, txo porosity thiab inclusions, thaum compound tshuab sib npaug zog faib thiab txhim kho weld uniformity.

[Duab: Daim duab 3. Kev cuam tshuam ntawm cov txheej txheem sib txawv ntawm welds]

Txoj kev tshuab tshuab tseem ceeb:
- Coaxial tshuab: Airflow yog coaxial nrog lub laser beam, symmetrically npog lub molten pas dej ua ke, haum rau siab - vuam ceev. Nws ua kom cov txheej txheem siab ruaj khov tab sis tuaj yeem cuam tshuam nrog laser tsom. Piv txwv li, nrog 1.2 hli galvanized automotive hlau, coaxial tshuab nce vuam ceev mus rau 40 mm / s, nrog spatter<0.1.
- Sab- tshuab: Airflow nkag los ntawm sab, tshem tawm cov ntshav thiab impurities, tsim nyog rau kev sib sib zog nqus nqus vuam. Rau 12 hli tuab Q345 steel ntawm 30℃sab- tshuab, nkag tau nce 18%, thiab porosity poob los ntawm 4% mus rau 0.8%.
- Kev sib xyaw tshuab: Kev sib xyaw coaxial thiab sab - tshuab, nws ib txhij suppresses oxidation thiab plasma cuam tshuam. Rau 3 hli tuab 6061 aluminium alloy nrog dual-nozzle tsim, porosity txo los ntawm 2.5% mus rau 0.4%, nrog tensile zog ncav cuag 95% ntawm cov khoom siv.

05 Xaus

Kev cuam tshuam ntawm kev tiv thaiv roj ntawm vuam zoo tseem ceeb yog los ntawm nws cov kev cai ntawm kev hloov hluav taws xob, molten pas dej ua ke thermodynamics, thiab tshuaj lom neeg cov tshuaj tiv thaiv:
1. Kev hloov hluav taws xob: Helium lub siab thermal conductivity accelerates txias, txo HAZ dav; argon tsis tshua muaj conductivity prolongs molten pas dej ua ke lub neej, muaj txiaj ntsig zoo ntawm daim ntawv nyias.
2. Molten pas dej ua ke stability: Airflow shear cuam tshuam rau molten pas dej ua ke ntws. Kev khiav dej num zoo suppresses spatter, thaum ntau dhau ua rau vortices thiab tsis xws luag.
3. Tshuaj tiv thaiv: Inert gases cais cov pa oxygen, tiv thaiv oxidation ntawm alloy ntsiab (xws li, Cr, Al). Active gases (piv txwv li, N₂) hloov weld zog ntawm cov khoom- kev daws teeb meem los yog kev sib xyaw ua ke, tab sis yuav tsum muaj kev tswj xyuas meej.

Laser & Electron Beam ua

Tau qhov twg los: Sau los ntawm pab neeg sau xov xwm ntawm WeChat pej xeem account "High-Energy Beam Processing Technology thiab Applications."