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Great Designs in Steel is Sponsored by
:
AK Steel Corporation, ArcelorMittal Dofasco, ArcelorMittal USA,
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LIGHTWEIGHTING AUTOMOTIVE BODY – ENABLERS
AND MANUFACTURING CHALLENGES
Daniel J. Grieshaber
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Outline
• Drivers
• Enablers
• Manufacturing Challenges
• Summary
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Drivers for Lightweighting
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Balance
Competitive Pressures
Manufacturability
Cost, Quality, Performance
Government Regulations
CAFE/CO
2Crash Performance
Emissions
Consumer Requirements
Cost
Quality
Performance + Features
Fuel Economy
Fuel Economy
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U.S. CAFE Standards
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Enablers
Product Design Optimization
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Integration of Efficient Load Paths
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Efficient Size and Shape
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‐ Based on strain maps, “unloaded metal” at the lower portion of thebracket was removed in final design.
‐ Removed metal was beyond original weld pattern. ‐ Tighter and fewer welds needed.
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Design Iteration of Geometry
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Local Reinforcement Strategy
(including Laser Welded Blanks and inserts)
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0
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Lightening Holes and Scalloping
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Thinnest Possible Part Gauges
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Best practice gauge and grade templates are used to drive designs.w w w . a u t o s t e e l . o r g
Increased Usage
of AHSS
Material & Design Impact on Lightweighting
Improved Design
through Efficient:
•Load Path
•Joint Design
•Part Size/Geometry
•Material Gauge
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Enablers
Light weight Materials
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4
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Body and Closure Metallic Material Content by TypeMild Steel
850 Pounds Advanced
HSS
2007 2015
800 Pounds with an Equal Footprint to 2007
North American Body Material Trends
Aluminum & Magnesium
Mild Steel Advanced
HSS
Bake Hardenable & Medium HSS Conventional
HSS
Aluminum & Magnesium
Source: Ducker Worldwide
Bake Hardenable & Medium HSS
Conventional HSS
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Dual Phase Steel Part Applications
Vehicle Components
• Front Structure
• Passenger Compartment & Side Structure
• Upper Structure
• Rear Structure
Underbody Applications M DP DP DP Mild HSLAw w w . a u t o s t e e l . o r g
Manufacturing Challenges
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Springback Management
Why:
• Still re-cutting dies – getting better, but
not there yet
• Dimensional requirements getting tighter
Topics:
• Springback reduction and management
through part and process design
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Effect of Beads on Springback
• Beads can
significantly reduce
sidewall springback
-5 0 5 10 15 20 340LA DP600 DP750 TRIP800 DP980 Material Wal l Openi ng Angle (d egrees) With Beads Without Beadsw w w . a u t o s t e e l . o r g
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Effect of 4-break Lock Flange on Sidewall Curl
• Springback
and sidewall
curl can be
reduced
through wall
stretching
enabled by
4-break lock
flange
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Effect of 4-break Lock Flange on Springback
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 340LA 590R DP600 DP750 TRIP800 DP980 Material Wal l Openi ng Angl e ( D egrees)
4 Break Lock Flange Short Blank
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Rocker Example – Material Change
Advantages Disadvantages
• Greatly Improved Shape Control
• Significantly Improved Part Dimensional Tolerances
• Improved Global Availability
• Higher Cost Compared to CR
Martensite
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Dimensional Control
Requirement
= +/- 0.5mm
Design /
Geometry:
•Panel thickness
•Radii
•Depth of draw
•Product features
Material
Properties:
•Yield Strength
•Tensile Strength
•Accurate Models
•Variability
Other:
•Shear Fracture
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A/SP Tribology Project
•High loads require stronger
materials
- Cast steel displacing cast iron
- Increased use of tool steel inserts and details
- Advanced coatings displacing chrome plating
Plasma nitride CVD, PVD, TD VC
•Guidelines under development
– Form, flange, trim, and pierce
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Die Materials & Surface Treatments
Under Evaluation
Substrates
• S7, D2
• Vanadis ® 4E
• Carmo®
• Caldie™
• M2
• M4
Surface Treatments
• CVD TiC
• PVD CrN, TiCN, TiAlN
• Ion Nitride with CrN
• Chrome Plating
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Carmo with PVD CrN, 65,000 hits
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Manufacturing
Challenges:
•Springback /
Dimensional Control
•Press Tonnage
•Die Wear, Galling,
Burrs, etc.
•Joining
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Impact of Manufacturing Challenges
Known Manufacturing
Processes (current infrastructure)
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Summary
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• Enablers
− Efficient Designs
− Effective Use of
Advanced High Strength
Steel
• Manufacturing Challenges
− Springback Prediction &
Management
− Tool Design &
Maintenance
Known Manufacturing Processes(current infrastructure) Manufacturing Challenges: •Springback / Dimensional Control •Press Tonnage •Die Wear, Galling,
Burrs, etc.
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Challenges for Suppliers
• Availability of Advanced High Strength Steels
– grades, coatings, gauges, and coil widths
• Accurate Springback Prediction Tools
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Great Designs in Steel is Sponsored by
:
AK Steel Corporation, ArcelorMittal Dofasco, ArcelorMittal USA,
