Transcript Friction Stir Welding Applications for Military Vehicles

Military Systems Group
Friction Stir Welding Applications for Military Vehicles
Keith Lunkenheimer – Richard Teruya – Thomas Pearson – William Segale – John Vollmer
Project Goal
Materials Tested
Feasibility Results
Magnesium (AZ31B) to Magnesium (AZ31B)
Magnesium (AZ31B) to Aluminum (6061-T6)
Aluminum Lithium (2090) to Aluminum (6061-T6)
To perform feasibility tests of friction stir
welding (FSW) using different metals for weight
reduction of weapon mounting brackets
Motivation: Within the Special Forces:
1lb≈$100,000 operating costs/year
Results for Mg to Mg
Mg is 34.5% lighter than Al but 13.4% weaker
Al-Li is 4% lighter than Al and 45.3% stronger
Percent of Parent Sample Tensile Strength
Friction Stir Welding
Tensile Strength (1500 RPM)
Process
31.00%
30.00%
29.00%
28.00%
27.00%
26.00%
25.00%
24.00%
23.00%
3
9
12
Traverse Rate (inches per minute)
Parent Sample
Sample
6
Tool Bit
Tool
Tool
Bit Bit
Results for Mg to Al
Sample
Sample
Average Peak Stress (MPa)
80
Clamping
Device
Clamping
Clamping
Device
Device
50%
Percent of Parent Sample Tensile
Strength
70
MPa
60
During a weld, a rotating cylindrical tool is driven through
the material to be welded
Friction Stir Welding Machine
Tensile Strength (1000 RPM)
Close-up of FSW machine
50
40
30
20
10
0
This heats the material to a plasticized state and literally
stirs the two pieces together
3
6
9
12
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
3
Traverse Rate (inches per minute)
6
9
12
Traverse Rate (inches per minute)
Results for Al-Li to Al
Parameters: Plunge Depth, Traverse Rate, Tilt angle,
Rotation Speed, Applied Force
Parameters for Optimization
Mounting Bracket
• Tool Geometry
• Machine Improvement
Test Sample Preparation Before FSW
Test Sample Preparation After FSW
- Force control - Auto Zero - Strength - More axes
Weight Savings
Original 6061 design weighted 23.96 lbs
With Al-Li: 20.35 lbs, a savings of ~3.5 lbs
Original Design
provided by MSG
Modified Design
employing FSW
Cost Savings
~$350,000 savings/year if used by special forces