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High quality & consistent weld

From thin to very high thickness

Minimum distortion

To join high melting point refractory

metals with very high quality

Metallurgical cleanliness

Need for EBW

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N

Advantages

High energy density & low energy input allows less shrinkage &

distortion, narrow HAZ

High quality, contamination free weld

High conductivity materials can be welded

Finish machined and intricate parts can be joined

Highly concentrated beam, less thermal effects on materials to be

joined

Refractory materials & dissimilar material combination can be

effectively joined

High aspect ratio welds allow single pass for heavy thickness material

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Deep & Narrow weld zone

Fusion area under

Conventional weld

Fusion area under

EB weld

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Basic principle

of

Electron Beam

Welding

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Electron Beam Welding

Welding Gun : Direct/ Indirect heating

Cathode : Temperature: 2538 deg.C

Anode : With a hole in the centerWehnelt : Grid

Focus Coil : for focussing

Deflection coil : for deflection of beam

Vacuum chamber

Movement mechanisms

Controls

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Low voltage type : 30kV, 15kW Hard

vacuum

Medium voltage : 60kV, 60kW Hard

vacuum, soft vacuum

High Voltage : 125-175kV, 120kW

Hard vacuum,soft vacuum and

Non vacuum

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Electron Beam WeldingMachine details

Vacuum selection: Depends on type of material to

be welded and depth to be welded

Hard vacuum for reactive materials like

zirconium

Soft vacuum for steel and alloys

Non vacuum with inert gas shield with low depth

to width ratio.

Optical viewing system: Telemicroscope with

cross hair or video camera with monitor

Vacuum pumping: Mechnical pump, diffusion

pump or turbo molecular pumps with coolers

Gun Mobility, wire feeding, seam tracking

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Electron Beam Welding-PROCESS VARIABLES

ACCELERATION VOLTAGE: Controls the spot

size. Spot size can also be controlled by focus coil.

Controls penetration BEAM CURRENT: Controls bead width, beam

power. Controlled by Wehnelt supply

BEAM FOCUS: Controls position of focus point

WELDING SPEED: Controls heat input, depends

on depth and width of weld and thermal

conductivity.

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Electron Beam Welding-

Welding of materials Welding of St.steels 90% TS

Aluminium 80% TS

Titanium alloys 100% TS

Berillium 50% TS

Zircalloys 100% TS

Columbium 100% TS Molybdenum better than arc welding

Tungsten

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Joint Design Butt Joint

T Joint

Flange to Shaft joint

Lap joint

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Applications Nuclear

Aero Space

Electronics

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Products Turbine blades

Compresser vanes

Blade to blade

Blade to flanges

Compresser rotor shafts

Instrumentation capsules

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Metallurgical effects

Reduced cracking

Improved weld properties

Narrow Heat Affected zone

Aluminium alloys can be welded

Blind welding can be done High frequency beam spinning will

reduce porosity

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Defects Porosities: Root, round, cross, border

type

Cracks: Longitudinal, transverse, coldcrack and necklace type cracking

Cold shut, spikes

Lack of fusion

Geometrical Defects Control of defects: by beam oscillation,

low speed and increased bead width.

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ADVANTAGES

WELD QUALITY

LOW DISTORTION

LOW HEAT INPUT LONG FOCUS

WIDE RANGE OF THICKNESS

WELDING OF DISSIMILAR MATERIALS

HIGH WELDING SPEED

ACCURACY OF REPEATABILITY

MULTIPLE PENETRATION

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LIMITATIONS VACUUM LIMITATIONS

MAGNETIC MATERIALS

PROFILE WELDING VARIABLE WORKING DISTANCE

VARIABLE PENETRATION

ACCESIBILITY CRITICALITY OF MACHINING

COST

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Technical considerations Work Handling and ancillary eqpt

Jigs and fixtures

Manipulators Drives and controls

Wire feed

Pumping equipment

Magnetic fields

Automatic controls

Maintenance

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Maintenance Aspects

Electron optical column andaccessories

High voltage supply system

Ancillary supplies and controls

Vacuum systems and vacuumpumps

Manipulators

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Quality control and inspection

Control of components before

processing

Control of parameters during

processing

Control after the operation

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Mechanism

ElectronBeam

ax1

dP1

ax1 - Unaffected zone of thickness

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Mechanism

a2

a1

o1

o2

Electron Beam

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1. Wehnelt

2. Cathode

3. Anode

4. Focusing coil

5. Focused beam

6. Diaphragm

I. Triode Gun

II. Triode Gun with polarized wehnelt

III. Diode Gun

Modes of Electron Beam

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Gun view

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Small chamber EB system

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High vacuum

chamber

6KW EB

Machine

Max Voltage : 70KV

Operating Voltage : 60KV

Chamber size : 350 x 350 x 350

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High power Electron Beam Welding at WRI

Power : 45 kW

Acceleration Voltage : 60 kV

Beam current : 750 mA

Chamber size :1500 X 1200 X 1200 mm

X-Y table movement : 700 X 400 mm

Gun movement : 1200 mm

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Electron beam welding machine with four workstation

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Materials

Steels:

With less than 0.4% are easily EB welded without preheat or PWHT

High Carbon & Tool steel - more than 0.5%C- weldable

Stainless Steel:

Austenitic Steel-easily weldable

Martensitic Steel-cracking problem due to lack of toughness

Ferritic Steel- magnetic in nature create beam deflection high cooling

rates inhibit carbide precipitation

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Copper & its alloys

Oxygen free Copper readily weldable

Oxygen bearing Copper - difficult to weld porosity,

spatter, expulsion of molten metal,uneven weld

surface

Alloying elements in copper presence of zinc posesproblems-porosity

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Aluminium & its alloys

Al HT alloys (2xxx,6xxx,7xxx) are crack sensitive

Use of filler - thin strips Proper choice of parameters & procedure

Use of PWHT

2xxx series effectively welded-higher yield strength obtained

with heavier gages 6xxx series -slightly affected by the heat cycles

7xxx series -difficult to join- apply low speed Zinc - high

vapour pressure, creates porosity

Al non HT alloy (3xxx,4xxx,5xxx)

Easily weldable without cracking in fusion & HAZ

5xxx series successfully welded (12.7mm) - Mg content is

preferentially vaporised

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Pure Titanium and Alpha alloys

Beta-alloys

Dual phase alloys

- easily EB weldable

- good weldability & formability

in annealed & solution treated

condition

- Weldable, 20% or moreamount of beta phase

difficult to weld

Titanium & its alloys

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Aerospace application

HIGH QUALITY

WELDING IS

ACHIEVED

THROUGH EBW

FOR TITANIUM

GAS BOTTLE

MANUFACTURE

TITANIUM PROPELLANT TANK

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Applications of EBW

Precombustion

chamber

Turbo charger

Wheel

Cardiacpacemakers

Gasturbine

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Copper/steel weld Niobium super conductive Cavities

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180

58 3 58 3 58

Connectingpiece

Expansion

strips

Spacer

strips

Schematic diagram of the joint

Cu-Cr-Zr cast connecting piece - OFC expansion strips

Expansion

strips

connecting

Piece

15 20 15

EBweld

Component description

Flexible copper terminal assembly used in 500MW water-cooled generator for

transferring the full stator current (16.2kA) from stator winding bus bars to

terminal bushings. The assembly remains in side the generator with H2

cooling and subjected to continuous vibration

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Connecting pieces

Each assembly con sists of:

four connect ing pieces

twelve expansion str ips

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Connecting pieces

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Each assembly - 4 connecting pieces& 12 expansion strips.

Ag coated connecting pieces - Cu-Cr-

Zr sand casting.

Expansion strip OFC 2 Cu strips of

0.5X58X265mm & 49 Cu strips of

0.3X60X265mm - diffusion welded

together.

Case studyEBW of flexible copper terminal assemblies for 500MW generators..

Half assembly

Connecting

piece

Expansion

strips

Chemical analysis of OFC

Cu Cr Zn Fe Si P S Mn

98.48 1.38 0.024 0.035 0.014 0.0063 0.0254 0.004

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Close-up view of EB welded joint

58mm 58mm 58mm

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Case stud yEBW of flexible copper terminal assemblies for 500MW generators..

EB welding parameters used for jointsJoint No. Accln

voltage, kVBeamcurrent, mA

Focuscurrent, A

Heatingcurrent, A

Weldingspeed,cm/min

1-weld 49.9 344 4.08 3.3 60

1-cosmetic 49.1 147 4.21 3.3 1202-weld 48.2 345 4.04 3.3 60

2-cosmetic 49.2 110 4.19 3.3 603-weld 48.6 320 4.09 3.3 60

3-cosmetic 49.7 105 4.52 3.3 90

4-weld 47.3 324 4.14 3.3 604-cosmetic 52.2 135 4.61 3.3 90

Macrophotograph

of the EB weld joint

Close-up view of EBW joint

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The silver coated connecting pieces are made up of Zr-Cr-Cu sandcasting as per HW 19992 specification

Chemical composition

Cr - 0.70 wt%Zr - 0.07 wt%

Mechanical properties

Ultimate Tensile Strength: 465.87 Mpa

Yield Strength : 324.22 Mpa

Elongation : 14.42%

Properties of Zr-Cr Cu alloy casting

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Cu expansion strips

Oxygen free deoxidised copper with low residualphosphorous content and high electrical

conductivity

Copper : 99.90 wt %

Phosphorus : 0.003 wt %

UTS : 20-25 kP/mm2

Elongation : 32-38 %

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Macrophotograph of EB welded joint

Zr-Cr-Cu alloy

Cu Strips20mm

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Arrangement of Copper strips

200m

Zr-Cr-Cu alloy

Strips

10.3mm

100m

2

3

1

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Microstructure of EB welded joint

200m

WELDStrip

HAZ

200m

Strip

HAZ

Weld

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Micro hardness results (LECO M400-H)

100

120

140

160

180

200

220

240

260280

Strip HAZ Weld Zr-Cr-Cu

Location

Ha

rdness,

HV

500ggg

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Tests conducted

Radiography testSound weld metal

Occasional depression due to oxide expulsion

Electrical conductivity study

Ohmic resistance measured

Zr-Cr-Cu :15 mExpansion strips :17 m

Welded assembly :32 m

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EB welding of AISI 316 Stainless steel

D

I

View from TOP

show smooth surface

without undercut

View from ROOT

show full penetration

Case study

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EB WELDING PARAMETERS FOR AISI 316 STAINLESS STEEL

Weldtype

t,mm

Acceln.volt, kV

Beamcurrent, mA

W-Gmm

Speedmm/min

Remarks

Bead 38 47 300 300 400 25mm penetrationBead 38 47 300 250 400 29mm penetrationBead 38 48 300 200 400 32mm penetration.Bead 38 50 345 200 400 Full back penetrationBead 38 53 345 200 440 Good penetrationJoint 38 53 350 200 400 Insufficient penetrationJoint 38 54 320 200 440 tack failure

Joint 38 54 340 200 440 good back penetrationJoint 38 54 350 200 480 Joint okJoint 38 54 350 200 480 Good joint. OptimalJoint 34 52 320 200 500 Good joint

Tensile test resultsNo. Ultimate load Kgf UTS -Kgf/mm Fracture position25-1 17900 59.7 Weld25-2 18050 60.2 Weld

C t d

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Microstructure of fractured surface of the tensile specimen

Dimple structure

improves the

toughness of the

weld metal in EB

welded AISI 316

stainless steel in

as weldedcondition

Case stud y

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(2) EBW1

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