Post on 16-Apr-2020
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Dual-Phase Steel forDoor Outer Application
Great Designs in SteelFebruary 19, 2003
Azfar QamarFord Motor Company
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• Background• Front Door Outer Study• Summary
Dual Phase Steel for Door Outer Application
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Background
• Drivers for Improved Dent Resistant Steels
• Factors that Influence Dent Resistance• Dual Phase (DP500) as Potential Solution
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BackgroundDrivers for Improved Dent Resistant Steels
• Increase Customer Satisfaction
• Reduce Warranty Claims
• Reduce In-Plant Damage
• Vehicle Weight Savings/Avoidance
• Cost Savings/Avoidance– Beta Patch Removal
– Thickness Reduction
– Allow Displacement of Aluminum Applications
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BackgroundFactors That Influence Dent Resistance
• Material Yield Strength – After Forming and Paint Bake
• Panel Thickness • Stiffness
– Elastic Modulus
– Geometry (Curvature)
– Support and Reinforcement
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BackgroundDP500 Steel as Potential Solution
• Good / Excellent Formability– Superior Formability for Given Strength Level
•Low YS/TS Ratio •High N-value
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BackgroundDP500 Steel as Potential Solution
X 1500
15% Martensite, Ferrite Grains
X 200
DP500 Microstructure
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BackgroundDP500 Steel as Potential Solution
• High Final Panel Strength– Rapid Strain Hardening
– High Bake Hardenability
• Exposed Surface Quality Capability
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BackgroundDP500 Steel as Potential Solution
True Stress - True Strain CurvesAs Shipped
0
100
200
300
400
500
600
700
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
True Strain
True
Str
ess
(ksi
)
BH300
BH250BH280
DP500
BH210BH180
DS
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BackgroundDP500 Steel as Potential Solution
True Stress - True Strain CurvesPaint Baked after 2% Prestrain
0
100
200
300
400
500
600
700
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
True Strain
True
Str
ess
(ksi
)
BH210BH250
BH280
DP500
BH300
DS
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Front Door Outer Study
Ford Front Door Outer (Test Case Study)
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Front Door Outer Study
• Steel Products Analyzed• Manufacturability
– Without any changes to tooling and/or process
• Dent Resistance Performance
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Front Door Outer StudySteel Products Analyzed
Product YS (Min)
Part YS* (Min)
UTS (Min) n-bar
BH210 EG (0.8 , 0.9 mm) 210 260 N/A 0.20
DP500 EG (0.8 mm)
270-350 370 500 0.20
* YS after 2% Strain and Paint Bake
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Front Door StudyDP500 Manufacturability
• Stamping– Draw Die Formability– Flanging– Dimensional Control
• Assembly– Welding– Hemming
• Surface Quality
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DP500 ManufacturabilityStamping - Draw Die Formability
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DP500 ManufacturabilityStamping - Draw Die Formability (FLD)
FRONT DOOR OUTER - BH210t = 0.80mm
•0
•20
•40
•60
•80
•100
•120
•140
•-60 •-40 •-20 •0 •20 •40 •60
FRONT DOOR OUTER - DP500t = 0.80mm
•0
•20
•40
•60
•80
•100
•120
•140
•-60 •-40 •-20 •0 •20 •40 •60
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DP500 ManufacturabilityStamping - Draw Die Formability (Panel Strain)
0.00.51.01.52.02.53.03.5
A B C D E F G H I J K L M N O
Location
Maj
or S
trai
n, %
BH210 DP500
0.00.20.40.60.81.01.21.41.6
A B C D E F G H I J K L M N O
Location
Min
or S
trai
n, %
BH210 DP500
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DP500 ManufacturabilityStamping - Flanging
Split/TearEdge-Burr
Minor trim and flange die modifications have since been made to alleviate issues
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DP500 ManufacturabilityStamping - Dimensional Control
Passed Dimensional Control Requirements
12
345
678
910
11
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DP500 ManufacturabilityAssembly - Welding
Successful Welding With No Process Changes
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DP500 ManufacturabilityAssembly - Hemming
BH210
DP500HEM
Successful Hemming With No Process Changes
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DP500 ManufacturabilitySurface Quality
• Panel Surface Inspection– Passed Ford Product Audit (FPA) Criteria
• Paintability – High Quality Rating
•“Wave Scan” Analysis
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Front Door Outer StudyDent Resistance Performance
1 2 3 4
5 6 7 8
Dent Locations
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Dent Resistance PerformanceA/SP Static Dent Test
050
100150200250300
1 2 3 4 5 6 7 8
Location
0.10
mm
Den
t Loa
d, N
0.80mm BH210 (w / Patch) 0.90mm BH210 (w / Patch)0.80mm DP500 (w / Patch) 0.80mm DP500 (No Patch)
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Dent Resistance PerformanceA/SP Dynamic Dent Test
1 2 3 4 5 6 7 8
0.0000
0.0025
0.0050
0.0075
0.0100
0.0125
0.0150
0.0175
0.0200
0.0225
Location
Mea
n of
Den
t Dep
th
D ynamic Dent Test .9mm BH210 vs .8mm BH210 vs .8mm DP500
.8mm BH210
.9mmBH210
.8mm DP500
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Front Door Outer StudyResults/Conclusions
• No significant manufacturability issues • Good surface quality• CMM study - comparable to production
doors• Dent Resistance Performance:
– .8 mm DP500 better than 0.9 mm BH210 (w/patch)
• Application of DP500 appears feasible
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Dual Phase Steel for Exposed Body Outer Applications - Summary
• Dual Phase Steel (DP500) indicates performance attributes that result in improved dent resistance
• The application of DP500 for door outer applications appears feasible
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Acknowledgements
• Ford would like to acknowledge Ispat Inland for their dedication to this effort
• Product Development, Trial Materials and Support
• Ford personnel deserving special recognition:
Scott Blaser Dave ChaoGreg Dobieralski Carrie GordanPaul Nagle Mike NagrantChuck Myers Bill RileyJim Robin Gary Rocheleau