Laser Joining of Aluminum with Filler Wire
Steffen Mueller
Craig Bratt, Christian Gebhardt, Thomas Kretzschmar
Fraunhofer USA
Center for Coatings and Laser Applications
Plymouth, Michigan.
© Fraunhofer USA
Outline
 Purpose of Using Filler Wire
 Aluminum Alloys and Types of Filler Wire
 Weld Setup and Equipment
 Laser Welding Processes
 Application Examples
 Conclusions
© Fraunhofer USA
Need For Mass Reduction in Cars
 Federal economy regulations require significant improvement in fuel efficiency,
in order to:
•
•
•
Save fuel costs for car owner
Save oil/energy
Reduce carbon dioxide pollution
2025
54.5 MPG
Sept.2012
29.3 MPG
2017
36.6 MPG
(fleet wide average)
(fleet wide average)
 One solution:
Reduce vehicle weight as much
as possible!
“Around 400lb weight loss for an
Average car is required to achieve
54.5 mpg”
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Germany
USA
(fleet wide average)
Benefits of Using Aluminum for Automotive Applications
 Aluminum and it’s Alloys
•
Light – 2.7g/cm3  1/3 mass of Steel
•
High strength-to-weight ratio – depending on
alloy and heat treatment, up to 300 MPa
•
Corrosion resistant
•
Easy to fabricate
•
In some cases difficult to weld
 Typical Aluminum Alloy Series for Automotive Applications
•
5000er series – Al-Mg alloy (e.g. Al5083, Al5754)
•
6000er series – Al-Mg-Si alloy (e.g. Al6061, Al6083)
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Purpose of Using Filler Wire
 Metallurgical Requirements
 Dimensional Requirements
 Post-Weld Requirements
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Purpose of Using Filler Wire
 Metallurgical Requirements
•
Susceptibility to solidification cracks
Relative Crack Sensitivity
Solidification Cracking Curve
Percentage of Alloying Addition
Source: Maxal [3]
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Purpose of Using Filler Wire
 Metallurgical Requirements
•
Loss of alloying elements
Source: M.Pastor et al.[1]
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Source: J.Weston, et al. [2]
Purpose of Using Filler Wire
 Dimensional Requirements
•
Different weld specification, depending on application
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Purpose of Using Filler Wire
 Dimensional Requirements
•
Increase of cross-sectional area with Filler wire
Increase of cross-sectional area
Avoid of undercut/notches
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Purpose of Using Filler Wire
 Post Weld Requirements
•
•
Tensile Strength and Elongation requirements close to parent material
Forming of welded sheets
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Aluminum Alloys and Types of Filler Wire
 2xxx Aluminum Alloys
•
Suitable filler wire for weldable alloys: Al2319, Al4145 filler wire
 5xxx Aluminum Alloys
•
•
•
Alloys with low Mg content: Al5183, Al5356, Al4047 filler wire
Alloys with high Mg content: Al5183, Al5356, Al5556 filler wire
For increased ductility and toughness: Al5356 and
Al5554 filler wire
 6xxx Aluminum Alloys
•
•
Best filler wire for reducing crack sensitivity:
Al 4047 and Al4043 filler wire
For increased strength and ductility:
Al 5183 and Al5356 filler wire
Welding of dissimilar Al-alloys requires different filler wire!
© Fraunhofer USA
Weld Setup and Equipment
 Laser for Welding of Aluminum
•
Absorption of Laser beam depending on wavelength
- CO2 Laser
- Diode Laser
- Nd:YAG/Disk/Fiber Laser
Diode Laser
900-1030 nm
•
High beam quality
•
Back reflection protection
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Disk/Fiber/
Nd:YAG Laser
CO2 Laser
10.6 μm
Weld Setup and Equipment
 CNC-machines and Robots
•
•
Flexibility
Accuracy
Multi-Axis CNC-machine for large structural aircraft
components
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Industrial Robot for sheet
metal welding
Weld Setup and Equipment
 Welding Optics for Aluminum Welding and Filler Wire Feeding
•
•
Laser beam spot size
Single Spot and Twin Spot Optics
 Filler Wire Feeding Equipment
•
•
•
Push-pull system
Wire Feed Torch
Roller groove
Twin-spot weld head with filler
wire torch for robotic applications
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Push-pull wire feed system with
enclosed wire spool cabinet
Weld head with filler wire torch
and integrated clamp tool
Laser Welding Processes with Filler Wire
 Aluminum Sheet Laser welding with filler wire
 Thick Section Aluminum Laser welding with filler wire
 Laser Hybrid welding
 Laser Remote Welding
Aluminum Sheet Welding
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GMAW-Laser Hybrid Welding
Laser Remote Welding
Laser Welding Processes with Filler Wire
 Aluminum Sheet Laser welding with filler wire
•
Al5083 sheet in overlap configuration, Al5183 filler wire
•
Al6061 sheet in butt joint configuration, Al4047 filler wire
•
Al5754 sheet in step joint configuration, Al5554 filler wire
Al5083 sheet and Al 5183 wire
Al6013 sheet and Al4047 wire
Al5754 sheet and Al5554 wire
Laser Power:
5 kW
Travel Speed
4.5 m/min
Wire Feed Rate: 4.5 m/min
Laser Power:
6 kW
Travel Speed
2.0 m/min
Wire Feed Rate: 6.8 m/min
Laser Power:
5 kW
Travel Speed
6.0 m/min
Wire Feed Rate: 6.0 m/min
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Laser Welding Processes with Filler Wire
 Thick Section Aluminum Laser welding with filler wire
•
High power, single pass weld – insufficient distribution of filler material
•
Low power, multi pass welds – consistent distribution of filler material
Si-content
8,5 %
Si-content
top
approx. 1,7 %
7,9 %
middle
3,9 %
bottom
Inconsistent filler material
distribution for plates above
5 mm
30 KW laser power and insufficient
filler wire in lower part of weld
© Fraunhofer USA
22 mm
middle
Narrow gap, multi pass welds with
more even filler wire distribution
Laser Welding Processes with Filler Wire
 Thick Section Aluminum Laser welding with filler wire
•
Narrow gap, multi pass welds
- 25 mm thick Al 6061 plates, Al4047 filler wire
Comparison between conventional weld (top)
and narrow gap, multi pass weld (bottom)
Narrow gap, multi pass
welds
Laser Power:
2.5 kW
Travel Speed:
1.0 m/min
Wire Feed Rate: 1.0 m/min
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Laser Welding Processes with Filler Wire
 Laser Hybrid welding
•
GMAW-Laser Hybrid welding
- Al 6061 sheets in lap fillet configuration, Al4047 filler wire
- Less dependent on work piece tolerances
Al6061 sheet and Al4047 wire
Laser- GMAW Hybrid Welding
process
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Laser Power:
3 kW
Travel Speed
3.0 m/min
Wire Feed Rate: 8.0 m/min
Application Examples
 Aluminum Hood Welding
•
•
•
Overlap joints
Al6111 to Al6111 and Al6111 to Al5754 material combinations
Stitch welds
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Application Examples
 Aluminum Airframe Components
•
Fully welded metallic integral structure
- Loading tolerant stringer-skin- joints
- Load adapted clip-skin-joints
- Damage tolerant skin-skin joints
Clip-Skin Joint
Skin-Skin Joint
Stringer-Skin Joint
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Conclusions
Increased use of Aluminum continuing for both automotive and aerospace
applications. In addition to advanced high strength steels, Aluminum will enable
future vehicle mass reduction and enable fuel efficiency improvements.
 Laser Welding is fast, flexible and automated and provides minimal heat input
and distortion compared to conventional welding technology.
 Laser Welding with filler material can reduce crack susceptibility and loss of
alloying elements, and can generate welds with strength properties close to the
parent material
 Laser welding process applications development for Aluminum is ongoing at
Fraunhofer as the Automotive and Aerospace industries continue to move towards
lighter more fuel efficient vehicles.
© Fraunhofer USA
Thank you for your
attention!
For additional information please contact:
Steffen Mueller
Fraunhofer USA – Center for Coatings and Laser
Applications
Plymouth Michigan USA.
Email: smueller@fraunhofer.org
Website: www.ccl-laser.fraunhofer.org
Telephone: 734 738 0551
© Fraunhofer USA