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IMPACT – FABRICATE

GDIS 2004February 18, 2004

Paul Geck, Bill Riley, Arnon WexlerFord Motor Company

Jayanth S. ChintamaniIspat Inland Inc.

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Outline

• Background• Objective• Forming• Welding• Summary

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IMPACT - FABRICATE

• Joint Project sponsored by– Ford– U.S. Army– AISI– University of Louisville

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FABRICATE TEAM

• Ford Motor CompanyMusa Azzouz (Consultant) Greg DobieralskiMike Azzouz (Consultant) Paul GeckPeter Miskech Wen-Sheng Lin John Chiang Bill RileyTim Cummins (Consultant) Arnon Wexler

• AISIKen Shaw, DofascoSean Martin, DofascoJayanth Chintamani, Ispat InlandLiang Huang, Ispat InlandKeith Laurin, Ispat InlandWei Wang, Severstal N.A.Dave Ruhno, USSMike Grimmet, USSPaul McKune, USS

• OthersTroy Design and ManufacturingQuality Metal CraftRoman Engineering ServicesEngineering Quality Solutions

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General Steel Grades

0

10

20

30

40

50

200 400 600 800 1000 1200 1400

Elo

ngat

i on,

%

Tensile Strength, MPa

UHSSUHSS

HSSHSS

Low Medium High Ultra-High

Mild

BH

CP

DP TRIP

FABRICATE

Current Product

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Objective

• Forming– Develop an understanding of formability of

specific Advanced High Strength Steels (AHSS) parts

• Welding– Characterize weldability of AHSS steels

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General Approach - Forming

• Preliminary evaluation of part formability using one-step FEA analysis

• Preliminary draw die development• Reassess product features for robust process• Detailed incremental FEA analysis• FEA results evaluated by the team• Soft tool build

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General Approach - Forming ..

• Form parts and review by the team• Recommend changes• Check surface quality of part• Conduct forming strain analysis• Post forming - Flanging• Conduct dimensional check

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Parts Selected for the Study

Shot GunMid TransverseCross Member

FenderDoor

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Rationale for Selection of Parts

• Fender, Door Outer– Customer appeal and functional performance– Degree of difficulty in tool buy out process– Severity of post forming operations

• Mid-transverse cross member, Reinforcement front fender inner (Shot gun)– Target for improving crash performance– Target for down gauging

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Steels used in the study

• Fender– 0.80mm BH210– 0.65mm DP500

• Mid-transverse X member– 1.50mm HSLA350– 1.50mm DP600– 1.40mm DP600

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Incremental FEA - Results

SPLITS &WRINKLE

SPLITS &WRINKLE

SPLITS

WRINKLE

1

2 4

3

4 Piece Stretch Draw Die

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Typical Panel Review

Areas of concern consistent with FEA predictions

1

24

3

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Final DP500 Panel FLD

Final Panel

L

F

L

K

J

G

F

EDC

A

B

010

2030

4050

60-15 -10 -5 0 5 10 15

Minor Strain (%)

Maj

or S

trai

n (%

)

Failure limit-Actual

Marginal limit-Actual

Failure Zone

Marginal Zone

Safe Zone

Developed production acceptabledraw die process

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Post Forming – Trimming & Flanging

GentlereliefNotcheliminatededge split

More Gradualtransitionof the flange

Hood line flange Reliefnotcheseliminatedcorner splits

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Lessons Learned - Fender

• 0.65mm DP500 product showed good potential for a production application with the following considerations– Clean edge condition after trimming is

important– Avoid notches in the door line flange– Gradual transition of flange length– Stretch flange conditions

• Minimize the trim flange length • Eliminate sharp notches in the flange

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Steels used in the study

• Fender– 0.80mm BH210– 0.65mm DP500

• Mid-transverse X member– 1.50mm HSLA350– 1.50mm DP600– 1.40mm DP600

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Incremental FEA - Strain Map

Radii to be softened

Thickness contourmap (0 to 20%)

SPLITS &WRINKLE

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Wrinkles in the Tunnel Area

In the part, no major forming issue other than wrinkles

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Tunnel Area - Wrinkles at the Bend

1

3

52 4

Varying length of line across the bend

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Modified Tunnel Design

MODIFIED PRODUCT

ORIGINAL DESIGN

Constant length ofline across the bend

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Springback Data

X

Z

Y

TUNNEL

SECTION - A

SECTION - B

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Springback - Tunnel

TUNNEL SECTION - Z

-2

0

2

4

6

8

31 32 33 40 41 42 16 19 20 17 18 21 49 50 51 4 5 6

Locations

Dev

iatio

n, m

m

1.50mm DP600 1.50mm HSLA350 1.40mm DP600

TUNNEL SECTION - X

-6

-4

-2

0

2

4

6

31 32 33 40 41 42 16 19 20 17 18 21 49 50 51 4 5 6

Locations

Dev

iatio

n, m

m

1.50mm DP600 1.50mm HSLA350 1.40mm DP600

1619

20

3132

33

4241

40

X

Z

Y

TUNNEL

4 65

181721

5150

49

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Lessons Learned - Cross Member

• DP600 product showed good potential for production of this part with the following considerations– Flange radii and radii along the hat section need

to be optimized for• Safe Formability• Controlling springback

– Engineer stiffeners to optimize springback

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IMPACT – FABRICATEWelding

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Welding Study

• Screening tests with differential material stackups– AC welding– AC versus MFDC (1200 Hertz)

• Stackups– More than 20 different stackups– Up to 3:1 thickness ratio– Up to 2mm gage

• Steels– Mild steel, HSLA and DP

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Screening Study – AC Welding

Potential issues with these grade and gage combinations

No. Material A Material BCurrent Range

(kA)Life Test

1 0.85mm DP EG 1.5mm BH 250 EG 3.6 17502 0.85mm DP EG 1.1mm BH 280 EG 3.8 20003 1.1MM BH 280 EG 0.7MM DP CR 2.9 20004 0.8mm BH 210 EG 0.65MM BH 210 EG 3.2 20005 0.65MM IF HD 0.65MM DP EG 2.4 7506 0.9MM BH 210 EG 1.3MM DP HD 1.4 17507 1.2MM DP HDG 1.3MM DP HD 1.1 7508 1.3MM DP HD 0.65MM BH 210 EG 2.0 10009 1.0MM BH 280 EG 0.65MM BH 210 EG 3.2 2000

10 1.5MM BH 250 HD 0.65MM BH 210 EG 1.4 125011 1.5MM BH 250 HD 0.85 MM BH 210 EG 1.7 200012 1.5MM BH 250 HD 0.7MM DP CR 2.0 200013 1.5MM BH 250 HD 1.0MM BH 280 EG 3.3 200014 0.65MM DP EG 0.65MM DP EG 2.0 200015 0.9MM DQ EG 0.7MM DP EG 1.3 175016 0.85mm DP HDG 0.95 mm DP HDG 2.3 75017 0.65mm DP EG 0.65MM DP EG 1.3 200018 0.65mm DP EG 0.85mm BH 210 EG 1.1 150019 0.7mm DP EG 0.7mm DP EG 2.4 200020 0.65mm DP EG 1.3MM DP EG 2.2 125021 0.85mm DP EG 0.65mm BH 210 EG 3.8 150022 1.3MM DP HD 1.3MM DP HD 1.3 1750

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AC and MFDC (1200 Hz)

AC MFDC

1.80mm DP600 HDG

0.80 Mild Steel HDG

1.80mm DP600 HDG

0.80 Mild Steel HDG

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AC and MFDC (1200 Hz)

0.0

0.5

1.0

1.5

2.0

2.5

3.0W

eld

Cur

rent

Ran

ge, k

AACMFDC

0.9m

m B

H E

G /

1.3m

m D

P H

D

1.2m

m D

P H

D /

1.3m

m D

P H

D

0.65

mm

BH

EG

/1.

3mm

DP

HD

0.65

mm

BH

EG

/1.

5mm

BH

HD

0.9m

m M

ild E

G /

0.70

mm

DP

EG

0.65

mm

DP

EG /

0.85

mm

BH

EG

0.65

mm

DP

EG/

1.3m

m D

P H

D

MFDC Weld current range is as good or better

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Multiple Stackups DP600 - MFDC

1.8 DP600 HD / 1.5 DP600 HD / 1.8 Mild HDMin Button Size = 6.0 mm

8

12

16

20

24

28

32

36

6 8 10 12 14 16 18WELD CURRENT (kA)

WEL

D T

IME

(Cyc

les)

NOK

OK

OK Recommended weld time for

HSLANOK

Increase weld time for DP600

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DP500 EG / Mild Steel – AC Welding

9

10

11

12

13

14

15

16

17

9 11 13 15 17

WELD CURRENT (kA)

WEL

D T

IME

(Cyc

les)

>1500 Amp, OK

>1500 Amp, OK

TYPICAL CASE0.65mm DP - 0.8mm Mild

WORST CASE0.65mm DP- 2.0mm Mild

9

10

11

12

13

14

15

16

17

9 11 13 15 17

WELD CURRENT (kA)

WEL

D T

IME

(Cyc

les)

>1500 Amp,OK

Electrode life: 2000 welds , OK Electrode life: 1250 welds, NOK

AC Welding OK for thin gage DP500Thickness mismatch has stronger effect than material/grade

Thickness Ratio < 2 Thickness Ratio > 2

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Summary

• AHSS require better integration between product and manufacturing engineering

• FABRICATE project supported the development of AHSS guidelines for– Forming– Welding– Product design