Electron Beam Welding

Metallurgy and Materials Engineering Department, University of Punjab Lahore

1. ELECTRON BEAM WELDING
Group 04
Muhammad Ans (M14-349)
Muhammad Zeeshan (M14 -336)
Muhammad Ilyas (M14-321)
Ali Hassan (M14-338)

3. ELECTRON BEAM WELDING (EBW)

4. INTRODUCTION
Definition:
It is fusion welding process in
which a beam of high velocity
electrons applied to two materials
or work pieces to be melt and
joined.
As high velocity electrons strike
the surface to be joined, their
kinetic energy changes to thermal
energy causing work piece to fuse.

5. PRINCIPLE OF OPERATION
The electron beam is produced in high vacuum environment by electron gun.
The stream of electrons is given off from a tungsten filament which is heated
to about 2200’C.
The electrons gathered and shaped into beam by potential difference.
The beam is focused by passing through the field of electromagnetic or
magnetic coil.
Beams is focused to about 0.25 to 1mm diameter and power density of
about 10kw/mm
2
.
The operation is carried out in a vacuum in which the distance is only 1mm
from the work piece.
Deep penetration and very narrow affected zone is achieved by Electron
beam welding.

7. PROCESS
The cathode of electron beam gun is negatively
charged filament.
When heated it emits electrons.
These electrons accelerated by electric field.
As pass through the hole they focused by an
electromagnetic coil to a point at surface of work
piece.
The current range is 50-1000mA and 30-175kV.
The electron beam of very high intensity melt the
metal.
The diameter of focused beam is 0.3 to 0.8mm.
More density causes deep penetration (key
hole).
The energy required in per unit length for beam
is 1.5kJ/cm.
Speed should be maintained otherwise gas
bubbles will not leave.

8. MATERIALS TO BE WELDED BY
EBW
Almost all steels.
Aluminum and its alloys.
Magnesium alloys.
Copper and its alloys.
Titanium.
Tungsten.
Gold.
Material combination (e.g. Cu-steel, bronze-steel).

9. •Electron beam gun
•Vacuum chamber
•Vacuum pumping
•Telescope
•Work piece
•Power unit
Necessary Equipment

10. •The gun consist on a filament , cathode, anode and focusing coil.
•The cathode is generally made of tungsten and heated to a
temperature of 2500°C.
•Basic function of electron beam gun is to generate free electron
at cathode.
•Accelerate these electron to sufficient high velocity.
•To focus them over a small size of spot .
Electron Beam Gun

13. AllthoseProducts,whichrequirerelativelylow
distortion,areamenabletoelectronbeam
weldingtechnology.
Medical:Manymedicaldevicesarepreferably
weldedwithanelectronbeambecauseofthe
precisenatureoftheprocessandthe
autogenouswelding.
Electronic:Electronbeamweldingprocesslies
initsrobustnesstojoinmaterialslikealuminum,
copperorstainlesssteels,whicharecommonly
usedinsemiconductorfabricatingequipment
andelectronicpackaging.
Applications

14. Oil&GasEquipment:
TheflexibilityoftheElectronBeam
Weldingprocesscanproducecustom
tailoredjointswithsmallheataffected
zonesandminimalheataffectstothe
parentmaterial.
Automotive:
Theelectronbeamisusedtowelda
multitudeofgear/synchronizer,
clutch/shaftandplanetcarrier
componentsformanualandautomatic
transmissionsaswellastorque
convertersand impellers/shaft
assembliesforturbochargers.
Continue….

15. TheElectronBeamWeldingprocessisusedfor
demandingjoiningtasksinmanylow-andhigh-
techapplicationswithinsomeofthemost
sophisticateddefensesystems.
Powergeneration:
Highvaluecomponents,criticaltothe
functionalityofcomplexpowergenerating
systems,arepreferablyweldedwithanelectron
beam.
Aerospace:
Theaerospaceindustryheavilydepends
uponelectronbeamweldingasakey
manufacturingtechnology.EB Welded
componentsareusedinaircraft&rocket
engines,sensors,gears,actuatorsandair
frames.
CONTINUE..

16. Dissimilar Metals:also allows joining of dissimilar metals, i.e. those with
different melting points and thermal conductivities. Some combinations
which are un-weldableby other conventional processes are thus readily
electron beam welded.
Deep narrow welds: High depth-to-width ratio eliminates multiple-pass
welds. Penetration from .001” to 2”.
Strength: Welds up to 95% of the strength of the base material.
Versatility: Precise control and repeatability at speeds from 1 to 200 inches
per minute.
High Purity: Vacuum environment eliminates impurities such as oxides and
nitrides
Minimal Distortion: low distortion means intricate components can be
accurately joined
Reactive and refractory metals can be welded in vacuum (no
contamination).
HAZ: Very narrow heat affected zone (HAZ) due to lower heat input per unit
length than in arc welding.
Shielding Gas: no shielding gas required.
Advantages

17. Cost: very high equipment cost, the equipment can cost hundreds of thousands
to millions of dollars.
Complexity: The equipment is complex .In other words, more ways to do it
wrong;
OR
according to Murphy's law;
"if there is a way to do it wrong, someone will do”
Vacuum: High vacuum (10-3 –10-6 torr) is inconvenient (difficult).
Missed jointed: of dissimilar metal can be obtained due to beam deflection.
Precise alignment of the joints and the gun is required due to small beam size.
Disadvantages