IMPACT FABRICATE GDIS 2004 February 18, 2004 Paul Geck, Bill Riley, Arnon Wexler Ford Motor Company Jayanth S. Chintamani Ispat Inland Inc.
Outline Background Objective Forming Welding Summary
Joint Project sponsored by Ford U.S. Army AISI University of Louisville IMPACT - FABRICATE
FABRICATE TEAM Ford Motor Company Musa Azzouz (Consultant) Mike Azzouz (Consultant) Peter Miskech John Chiang Tim Cummins (Consultant) AISI Ken Shaw, Dofasco Sean Martin, Dofasco Jayanth Chintamani, Ispat Inland Liang Huang, Ispat Inland Keith Laurin, Ispat Inland Wei Wang, Severstal N.A. Dave Ruhno, USS Mike Grimmet, USS Paul McKune, USS Greg Dobieralski Paul Geck Wen-Sheng Lin Bill Riley Arnon Wexler Others Troy Design and Manufacturing Quality Metal Craft Roman Engineering Services Engineering Quality Solutions
General Steel Grades 50 Low Medium High Ultra-High Current Product 40 Mild FABRICATE Elongation, % 30 20 10 BH HSS DP CP TRIP UHSS 0 200 400 600 800 1000 1200 1400 Tensile Strength, MPa
Objective Forming Develop an understanding of formability of specific Advanced High Strength Steels (AHSS) parts Welding Characterize weldability of AHSS steels
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
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
Parts Selected for the Study Fender Door Mid Transverse Cross Member Shot Gun
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
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
WRINKLE Incremental FEA - Results 2 3 4 SPLITS 1 SPLITS & WRINKLE SPLITS & WRINKLE 4 Piece Stretch Draw Die
Typical Panel Review 3 2 4 1 Areas of concern consistent with FEA predictions
Final DP500 Panel FLD L Final Panel Developed production acceptable draw die process F Major Strain (%) 0 10 20 30 40 50 60 Safe Zone G Failure limit-actual Marginal limit-actual Failure Zone C E D L B J A -15-10 -5 0 5 10 15 Minor Strain (%) K F Marginal Zone
Post Forming Trimming & Flanging Hood line flange Relief notches eliminated corner splits More Gradual transition of the flange Gentle relief Notch eliminated edge split
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
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
Incremental FEA - Strain Map Radii to be softened Thickness contour map (0 to 20%) SPLITS & WRINKLE
Wrinkles in the Tunnel Area In the part, no major forming issue other than wrinkles
Tunnel Area - Wrinkles at the Bend 1 2 4 3 5 Varying length of line across the bend
Modified Tunnel Design ORIGINAL DESIGN Constant length of line across the bend MODIFIED PRODUCT
Springback Data X Y SECTION - A Z TUNNEL SECTION - B
Springback - Tunnel TUNNEL SECTION - X 1.50mm DP600 1.50mm HSLA350 1.40mm DP600 TUNNEL SECTION - Z 1.50mm DP600 1.50mm HSLA350 1.40mm DP600 6 8 Deviation, mm 4 2 0-2 -4-6 31 32 33 40 41 42 16 19 20 17 18 21 49 50 51 4 5 6 Deviation, mm 6 4 2 0-2 31 32 33 40 41 42 16 19 20 17 18 21 49 50 51 4 5 6 Locations Locations 20 33 42 32 19 41 16 31 40 X Z Y TUNNEL 21 51 18 17 50 4 6 5 49
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
IMPACT FABRICATE Welding
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
Screening Study AC Welding No. Material A Material B Current Range Life Test (ka) 1 0.85mm DP EG 1.5mm BH 250 EG 3.6 1750 2 0.85mm DP EG 1.1mm BH 280 EG 3.8 2000 3 1.1MM BH 280 EG 0.7MM DP CR 2.9 2000 4 0.8mm BH 210 EG 0.65MM BH 210 EG 3.2 2000 5 0.65MM IF HD 0.65MM DP EG 2.4 750 6 0.9MM BH 210 EG 1.3MM DP HD 1.4 1750 7 1.2MM DP HDG 1.3MM DP HD 1.1 750 8 1.3MM DP HD 0.65MM BH 210 EG 2.0 1000 9 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 1250 11 1.5MM BH 250 HD 0.85 MM BH 210 EG 1.7 2000 12 1.5MM BH 250 HD 0.7MM DP CR 2.0 2000 13 1.5MM BH 250 HD 1.0MM BH 280 EG 3.3 2000 14 0.65MM DP EG 0.65MM DP EG 2.0 2000 15 0.9MM DQ EG 0.7MM DP EG 1.3 1750 16 0.85mm DP HDG 0.95 mm DP HDG 2.3 750 17 0.65mm DP EG 0.65MM DP EG 1.3 2000 18 0.65mm DP EG 0.85mm BH 210 EG 1.1 1500 19 0.7mm DP EG 0.7mm DP EG 2.4 2000 20 0.65mm DP EG 1.3MM DP EG 2.2 1250 21 0.85mm DP EG 0.65mm BH 210 EG 3.8 1500 22 1.3MM DP HD 1.3MM DP HD 1.3 1750 Potential issues with these grade and gage combinations
AC and MFDC (1200 Hz) 1.80mm DP600 HDG 1.80mm DP600 HDG 0.80 Mild Steel HDG 0.80 Mild Steel HDG AC MFDC
3.0 2.5 2.0 1.5 1.0 0.5 0.0 AC and MFDC (1200 Hz) AC MFDC Weld Current Range, ka 0.9mm BH EG / 1.3mm DP HD 1.2mm DP HD / 1.3mm DP HD 0.65mm BH EG / 1.3mm DP HD 0.65mm BH EG / 1.5mm BH HD 0.9mm Mild EG / 0.70mm DP EG 0.65mm DP EG / 0.85mm BH EG 0.65mm DP EG/ 1.3mm DP HD MFDC Weld current range is as good or better
Multiple Stackups DP600 - MFDC 36 1.8 DP600 HD / 1.5 DP600 HD / 1.8 Mild HD Min Button Size = 6.0 mm WELD TIME (Cycles) 32 28 24 20 16 12 NOK NOK OK OK Recommended weld time for HSLA 8 6 8 10 12 14 16 18 WELD CURRENT (ka) Increase weld time for DP600
DP500 EG / Mild Steel AC Welding TYPICAL CASE 0.65mm DP - 0.8mm Mild WORST CASE 0.65mm DP- 2.0mm Mild WELD TIME (Cycles) 17 16 15 14 13 12 11 10 Thickness Ratio < 2 Thickness Ratio > 2 >1500 Amp, OK 9 9 11 13 15 17 WELD CURRENT (ka) >1500 Amp, OK WELD TIME (Cycles) 17 16 15 14 13 12 11 10 9 9 11 13 15 17 WELD CURRENT (ka) >1500 Amp, OK Electrode life: 2000 welds, OK Electrode life: 1250 welds, NOK AC Welding OK for thin gage DP500 Thickness mismatch has stronger effect than material/grade
Summary AHSS require better integration between product and manufacturing engineering FABRICATE project supported the development of AHSS guidelines for Forming Welding Product design