IMPACT – FABRICATE - American Iron and Steel Institute/media/Files/Autosteel/Great Designs in...w...
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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