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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