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Great Designs in Steel is Sponsored by:
ArcelorMittal Dofasco, ArcelorMittal USA, Nucor Corporation,
Severstal North America, Inc. and United States Steel Corporation
A Comparative Study of Joint Efficiency for
Advanced High Strength Steel
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John Bohr
A/SP Joining Technologies Team
Project Description
• Conduct a study on various grades of steel to quantify joint efficiencies of assorted joining and bonding methods.
• Methodology for this project was to produce typical welds/joints/bonds on lap-shear and/or coach peel coupons to generate tensile test (load-displacement)
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coupons to generate tensile test (load-displacement) curves for the varied process and material configurations.
• Project deliverables include the load displacement curve and calculations of joint efficiency, stiffness, and energy for each test configuration.
Joint Efficiency1
A numerical value expressed as the ratio of the strength of a
riveted, welded, or brazed joint to the strength of the parent
metal. In welding, the ratio of the strength of a joint to the
strength of the base metal, expressed in percent.
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strength of the base metal, expressed in percent.
(Coupon dimensions for tensile testing used in this study were derived from the AWS/ANSI D8 Automotive
Welding Standards.)
1 Definition from http://www.answers.com
Joint Efficiency Calculation Example25mm LASER Fillet Weld
Joint Strength = 4997 N
Parent Metal Strength = 8776 N
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joint efficiency η = joint strength / parent strength
joint efficiency η = 4997 / 8776
joint efficiency η = 57%
Joint Strength Metrics
Stiffness = Slope of the best fit
line in the elastic region
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Material Compositions – Phase I
Steel C Mn P S Si Cu Ni Cr Al Mo V Nb Ti N
Mild 0.07 0.049 0.006 0.0037 0.006 0.015 0.006 0.025 0.051 0.005 0.004 0.001 0.053 0.0044
590R 0.136 1.588 0.011 0.0066 0.115 0.024 0.01 0.031 0.033 0.013 0.002 0.041 0.002 0.0068
Chemical Compositions of Tested Steels (wt%)
•0.7mm Mild EG
•1.2 mm 590R GA
•1.2 mm DP600 GI
•1.15 mm DP780 GA
•1.0 mm Trip800 EG
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Steel Location Al(wt%) Fe(wt%) Coating Weight (g/m2) Ave. Al (wt%) Ave. Fe (wt%) Ave. Coating Weight (g/m2)
Mild Top 0.005 0.032 67.0
Bottom 0.005 0.040 66.2
590R Top 0.322 11.500 49.5
Bottom 0.330 11.500 49.0
DP600 Top 0.262 0.921 63.4
Bottom 0.263 0.728 65.4
DP780 Top 0.220 8.890 57.6
Bottom 0.249 9.410 47.5
TRIP800 Top 0.005 0.056 54.8
Bottom 0.004 0.054 59.60.005
0.235
0.263
0.326
64.4
52.5
57.2
0.036
11.500
0.825
9.150
0.055
Coating Analysis of Tested Steels
66.6
49.3
0.005
590R 0.136 1.588 0.011 0.0066 0.115 0.024 0.01 0.031 0.033 0.013 0.002 0.041 0.002 0.0068
DP600 0.101 1.857 0.011 0.0038 0.361 0.034 0.008 0.024 0.053 0.014 0.003 0.004 0.003 0.0118
DP780 0.114 2.09 0.017 0.0028 0.034 0.034 0.013 0.234 0.056 0.184 0.005 0.004 0.002 0.0091
TRIP800 0.194 1.677 0.014 0.002 1.659 0.033 0.016 0.026 0.042 0.013 0.004 0.005 0.004 0.0062
Processes
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Processes
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Methodology
• Five samples were prepared for each welding / joining process.
(45 mm x 105 mm coupons)
• Process setup verifications* were performed prior to tensile
samples being produced in order to ensure quality joints.
• GMAW and LASER welds were cross-sectioned and analyzed
to verify conformance with requirements.
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to verify conformance with requirements.
• For each process, two specimens were tensile tested. If peak
loads were within 5%, the data from the specimen with the
lowest peak load was used.
• If peak loads were greater than 5%, a third specimen was tested,
the data from the specimen with the median peak load was used.
*Note: Except for the A/SP Starting Weld Schedules
MethodologySchematics for Test Specimens
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Mild Steel - Sample Results
YMMV
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YMMV
0.7 EG - Population Results
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Sample Load/Displacement Curves for 0.7 mm
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0.7mm Mild ResultsMild
Joining Process Energy (J) Joint Efficiency Peak Load (N) Stiffness (N/mm)
Parent Metal UTS (45X105) 151.90 100% 8776.0 45222.7
Arc Braze - Double fillet in a slot (13X25) 122.48 93% 8143.3 19675.2
GMAW Double fillet weld in a slot (13X25) 103.30 90% 7870.6 24766.5
Arc Braze - Single fillet weld in a slot (10X25) 61.72 82% 7222.8 22642.5
Arc Braze (25mm lap fillet) 37.79 76% 6678.3 32536.9
GMAW (AWS D8.8M) 33.94 74% 6488.4 27084.1
GMAW (manual - Operator A) 28.86 73% 6442.0 29041.6
GMAW (Optimized geometry) 26.41 73% 6379.1 24311.7
GMAW (OTC DL) 24.29 72% 6287.7 21192.6
GMAW (OTC DP-400) 23.81 70% 6182.9 23199.5
Laser (staple geometry) 33.01 70% 6172.6 22108.4
GMAW Lincoln STT 21.16 69% 6065.9 26812.3
Lincoln Power Mode 18.14 68% 5943.3 23394.7
GMAW (manual - Operator B) 20.07 67% 5904.7 25540.5
GMAW single fillet weld in a slot (10X25) 22.10 67% 5849.2 25629.1
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GMAW single fillet weld in a slot (10X25) 22.10 67% 5849.2 25629.1
GMA Cold Metal Transfer (Fronius) 15.46 63% 5529.7 29138.9
Laser (25mm lap) 17.35 62% 5400.4 21483.0
Arc Braze - Plug Weld (8mm hole) 29.35 61% 5386.6 21505.4
Laser MIG (25mm lap fillet) 10.90 61% 5375.6 24866.5
Arc Braze - Plug Weld (10mm hole) 22.85 59% 5162.3 15627.1
Laser (25mm lap fillet) 11.10 57% 4997.2 22916.4
GMAW - Plug Weld (10mm hole) 18.60 56% 4881.8 18099.1
Laser Braze (25mm lap fillet) 4.25 49% 4320.0 22892.7
GMAW - Plug Weld (8mm hole) 9.38 47% 4127.1 17724.3
Resistance Spot Welding (ProSpot i4) 6.75 39% 3384.3 14138.9
GMAW - Arc Spot 5.54 38% 3337.6 16535.4
Fronius Delta Spot 4.49 37% 3268.3 20558.5
A/SP RSW Starting Schedule (DC) 5.73 36% 3193.7 17480.0
Resistance Spot Welding (AWS D8.1M) 4.55 34% 2996.4 16386.0
A/SP RSW Starting Schedule (AC) 3.23 29% 2581.3 16091.2
Hemlok Rivet 1/4" 15.97 27% 2346.2 4170.5
Self Pierce Rivet (Henrob) 4.56 26% 2291.5 10889.8
Mechanical Clinch Tog-L-Loc (BTM) 1.72 26% 2272.4 15710.9
590R - Sample Results
YMMV
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YMMV
1.2mm 590R
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1.2mm 590R Results590R
Joining Process Energy (J) Joint Efficiency Peak Load (N) Stiffness (N/mm)
Parent Metal UTS (45X105) 426.31 100% 30081.5 61333.3
GMAW Double fillet weld in a slot (13X25) 17.50 76% 22907.8 37485.6
Laser (staple geometry) 46.94 73% 21860.9 35152.1
GMAW single fillet weld in a slot (10X25) 21.26 69% 20691.1 35505.8
GMAW (manual - Operator A) 21.33 68% 20348.1 37763.8
GMAW (OTC DL) 19.11 67% 20119.7 38983.8
Laser (25mm lap) 30.51 67% 20195.9 35723.1
GMAW Lincoln STT 26.46 66% 19808.4 37260.8
GMAW (Lincoln Rapid Arc) 15.49 66% 19873.3 35359.8
GMAW (Optimized geometry) 36.70 66% 19903.1 39715.2
Laser (25mm lap fillet) 28.46 65% 19527.3 35251.3
GMAW Lincoln Powermode 23.70 65% 19559.7 36065.2
GMAW - Plug Weld (10mm hole) 27.71 63% 18925.8 35408.9
Arc Braze - Double fillet in a slot (13X25) 9.01 62% 18551.2 39894.9
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Arc Braze - Double fillet in a slot (13X25) 9.01 62% 18551.2 39894.9
GMA Cold Metal Transfer (Fronius) 15.33 61% 18337.4 40065.0
GMAW (OTC DP-400) 17.28 61% 18455.9 39788.1
GMAW (AWS D8.8M) 15.63 60% 18120.3 38962.9
GMAW (manual - Operator B) 14.66 60% 18145.9 40815.6
Fronius Delta Spot 22.00 53% 15826.7 34213.2
Laser MIG (25mm lap fillet) 8.19 53% 16055.5 37795.1
A/SP RSW Starting Schedule (DC) 21.66 51% 15440.3 34573.6
Resistance Spot Welding (ProSpot i4) 14.85 47% 14025.0 35366.1
A/SP RSW Starting Schedule (AC) 11.43 47% 14041.2 33088.4
Arc Braze - Single fillet weld in a slot (10X25) 5.09 47% 14208.1 37632.8
GMAW - Plug Weld (8mm hole) 8.60 43% 12936.6 30863.0
Resistance Spot Welding (AWS D8.1M) 14.19 43% 13079.6 28805.4
Arc Braze - Plug Weld (10mm hole) 13.24 42% 12602.0 32137.1
Arc Braze - Plug Weld (8mm hole) 7.55 36% 10683.8 30066.0
Arc Braze (25mm lap fillet) 2.77 36% 10748.9 37576.9
Hemlok Rivet 1/4" 22.39 29% 8820.7 27237.9
Laser Braze (25mm lap fillet) 1.93 24% 7156.6 31123.7
Self Pierce Rivet (Henrob) 7.37 24% 7218.6 14438.3
GMAW - Arc Spot 1.94 22% 6627.4 29388.4
DP600 - Sample Results
YMMV
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YMMV
1.2mm DP600
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1.2mm DP600 ResultsDP600
Joining Process Energy (J) Joint Efficiency Peak Load (N) Stiffness (N/mm)
Parent Metal UTS (45X105) 339.94 100% 32527.0 60614.0
Laser (staple geometry) 79.70 73% 23806.7 36988.8
GMAW Double fillet weld in a slot (13X25) 44.63 71% 23174.3 39198.8
SPR/Adhesive (Rivbond Henkel 5087) 14.63 66% 21330.8 47963.7
Laser (25mm lap) 38.68 63% 20503.1 35155.6
GMAW (manual - Operator A) 34.57 63% 20649.8 39573.8
GMAW Lincoln Power Mode 26.71 62% 20072.9 36898.0
Laser (25mm lap fillet) 43.09 62% 20235.4 35649.5
GMAW (OTC DL) 20.59 59% 19133.1 37736.7
GMAW (Optimized geometry) 18.78 59% 19344.4 39437.2
GMAW (OTC DP-400) 16.24 58% 18885.0 39229.8
GMAW (Lincoln Rapid Arc) 21.93 57% 18653.6 37260.3
Arc Braze - Double fillet in a slot (13X25) 12.80 57% 18684.2 41656.7
GMAW (AWS D8.8M) 12.85 56% 18276.2 37494.2
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GMAW - Plug Weld (10mm hole) 23.99 55% 17784.0 34541.2
A/SP RSW Starting Schedule (DC) 29.96 54% 17434.5 36786.8
GMA Cold Metal Transfer (Fronius) 15.74 53% 17159.7 38739.5
GMAW (manual - Operator B) 13.71 52% 16763.3 38268.9
Fronius Delta Spot 34.99 52% 16840.9 35551.2
Laser MIG (25mm lap fillet) 8.37 50% 16142.6 39145.3
GMAW - Plug Weld (8mm hole) 20.11 50% 16272.8 31926.0
GMAW single fillet weld in a slot (10X25) 16.69 49% 15965.2 34786.5
Resistance Spot Welding (ProSpot i4) 23.61 48% 15460.0 35783.0
A/SP RSW Starting Schedule (AC) 20.47 47% 15234.6 34126.6
Arc Braze (25mm lap fillet) 3.60 42% 13565.7 36855.7
Arc Braze - Single fillet weld in a slot (10X25) 3.53 37% 12077.9 37637.2
GMAW Lincoln STT 3.11 37% 12125.5 38448.7
GMAW - Arc Spot 5.21 35% 11279.5 32101.7
Arc Braze - Plug Weld (8mm hole) 8.00 34% 11149.2 31972.5
Resistance Spot Welding (AWS D8.1M) 5.84 33% 10805.4 31327.3
Arc Braze - Plug Weld (10mm hole) 6.75 33% 10852.0 33263.3
Hemlok Rivet 1/4" 22.97 28% 8987.9 25990.6
Self Pierce Rivet (Henrob) 6.45 21% 6729.7 15351.8
Laser Braze (25mm lap fillet) 1.46 20% 6413.1 31789.9
TRIP800 - Sample Results
YMMV
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YMMV
1.0mm TRIP800
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1.0mm TRIP800 ResultsTRIP800
Joining Process Energy (J) Joint Efficiency Peak Load (N) Stiffness (N/mm)
Parent Metal UTS (45X105) 384.15 100% 35715.5 52837.4
GMAW Double fillet weld in a slot (13X25) 27.64 72% 25600.1 34420.7
Laser (staple geometry) 34.99 67% 23890.3 32813.2
GMAW (OTC DL) 19.57 66% 23561.4 34599.4
GMAW (Optimized geometry) 22.38 66% 23456.5 35267.8
GMAW (AWS D8.8M) 20.11 63% 22373.9 34302.4
GMAW (manual - Operator A) 16.43 62% 22142.8 34727.5
GMAW (manual - Operator B) 16.49 62% 22034.6 35323.6
Laser (25mm lap) 22.69 62% 21978.5 31916.5
GMAW (OTC DP-400) 15.10 61% 21957.5 34744.1
GMAW Lincoln GMAW Powermode 17.42 60% 21593.9 32191.8
GMAW single fillet weld in a slot (10X25) 15.46 59% 21163.6 32367.5
GMAW Lincoln STT 12.17 58% 20764.1 33297.0
GMA Cold Metal Transfer (Fronius) 10.19 57% 20502.0 37166.7
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GMA Cold Metal Transfer (Fronius) 10.19 57% 20502.0 37166.7
GMAW (Lincoln Rapid Arc) 12.23 57% 20370.6 35319.1
Laser (25mm lap fillet) 18.03 55% 19663.3 32573.1
Fronius Delta Spot 22.74 52% 18548.1 32200.9
Laser MIG (25mm lap fillet) 7.54 49% 17605.8 33484.0
GMAW - Plug Weld (10mm hole) 7.86 48% 17000.5 32185.2
Arc Braze - Double fillet in a slot (13X25) 6.48 47% 16943.0 37583.8
A/SP RSW Starting Schedule (DC) 8.55 45% 16037.4 31681.8
Arc Braze (25mm lap fillet) 4.23 42% 15099.7 32981.4
Resistance Spot Welding (ProSpot i4) 9.09 41% 14602.4 31065.2
GMAW - Plug Weld (8mm hole) 6.10 41% 14587.0 29084.6
Resistance Spot Welding (AWS D8.1M) 11.23 40% 14188.1 28554.1
Arc Braze - Single fillet weld in a slot (10X25) 3.57 36% 12709.0 34689.6
Arc Braze - Plug Weld (10mm hole) 7.63 36% 12685.3 31164.8
A/SP RSW Starting Schedule (AC) 6.47 34% 12289.7 30896.2
Arc Braze - Plug Weld (8mm hole) 3.20 28% 10024.1 32495.0
GMAW - Arc Spot 5.02 28% 9959.8 26786.2
Hemlok Rivet 1/4" 14.27 23% 8248.3 29282.6
Self Pierce Rivet (Henrob) 7.44 18% 6339.9 12328.2
Laser Braze (25mm lap fillet) 1.04 17% 6170.1 31757.7
DP780 - Sample Results
YMMV
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YMMV
1.15mm DP780
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1.15mm DP780 ResultsDP780
Joining Process Energy (J) Joint Efficiency Peak Load (N) Stiffness (N/mm)
Parent Metal UTS (45X105) 391.95 100% 44201.3 60796.6
Laser (staple geometry) 39.48 61% 26913.3 36232.9
GMAW Double fillet weld in a slot (13 x 25) 24.75 61% 27121.2 37375.6
GMAW Lincoln Powermode 25.37 58% 25461.4 36749.7
GMAW (OTC DL) 18.19 54% 23799.8 38030.1
GMAW (manual - Operator A) 18.18 53% 23502.1 38729.2
Laser (25mm lap) 21.56 52% 22768.6 34096.6
Laser (25mm lap fillet) 22.53 52% 23134.7 36825.7
GMA Cold Metal Transfer (Fronius) 15.85 51% 22706.1 37682.7
GMAW single fillet weld in a slot (10x25) 12.87 49% 21548.1 38417.8
GMAW (AWS D8.8M) 11.79 49% 21752.3 37141.1
GMAW (Optimized geometry) 15.79 49% 21866.2 39259.3
Arc Braze - Double fillet in a slot (13X25) 10.49 48% 21122.2 40994.9
Fronius Delta Spot 22.66 46% 20237.6 35381.4
GMAW (manual - Operator B) 9.94 45% 19952.0 37109.9
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GMAW (manual - Operator B) 9.94 45% 19952.0 37109.9
Laser MIG (25mm lap fillet) 10.51 44% 19242.8 38884.3
A/SP RSW Starting Schedule (DC) 18.75 44% 19338.2 35390.8
GMAW (Lincoln Rapid Arc) 6.81 42% 18430.8 37705.6
GMAW - Plug Weld (10mm hole) 10.36 41% 18210.7 34080.0
GMAW (OTC DP-400) 7.10 38% 16584.1 38241.1
A/SP RSW Starting Schedule (AC) 10.10 38% 16654.8 33129.9
Resistance Spot Welding (ProSpot i4) 13.45 38% 16697.8 33593.7
GMAW - Plug Weld (8mm hole) 12.12 37% 16329.3 31478.6
GMAW Lincoln STT 6.19 36% 16112.2 37671.9
Resistance Spot Welding (AWS D8.1M) 13.04 35% 15479.6 30528.6
Arc Braze - Single fillet weld in a slot (10X25) 5.40 33% 14374.5 37387.0
Arc Braze - Plug Weld (10mm hole) 9.64 29% 13026.6 31767.4
Arc Braze (25mm lap fillet) 3.94 28% 12484.5 35944.2
Structural Adhesive (Henkel 5087) 3.93 28% 12582.1 36984.2
Arc Braze - Plug Weld (8mm hole) 8.47 25% 10888.6 29473.1
Hemlok Rivet 1/4" 14.40 20% 9030.0 27964.6
Self Pierce Rivet (Henrob) 7.74 19% 8233.1 16065.9
GMAW - Arc Spot 3.15 19% 8610.4 31873.6
Laser Braze (25mm lap fillet) 2.05 16% 7081.2 35570.1
Joint Efficiency
Process Comparisons
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Spot Weld and Rivet Comparison
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Spot Weld and ProSpot Comparison
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General Observations
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Observations
• AHSS can be successfully welded/joined/bonded by many processes
• Various joining processes result in different strength metrics.
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strength metrics.
• Joints with similar tensile peak loads can have different Energy (J) values.
• Joints with similar Energy (J) values can have different tensile peak loads.
Observations
• GMAW and LASER processes with steel filler
have higher joint efficiency in AHSS material
than Arc Braze or LASER Braze
• RSW and SPR in combination with structural
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• RSW and SPR in combination with structural
adhesive produced specimens with the highest
joint efficiencies.
• The joint efficiency trend line generally
decreases as material strength increases.
Acknowledgements
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Additional Information – Phase I
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What’s Next
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Phase I - Learnings
• Include HSLA and Martensitic materials for
additional Joint Efficiency and strength
calculations in Phase II
• Reduce coupon overlap to 15mm
• Expand the conditions studied to include a
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• Expand the conditions studied to include a
15mm, 20mm and 25mm lengths for
continuous joining processes
• Include fatigue samples
• Include coach peel tests
FOR MORE INFORMATION
• CONTACT: John Bohr, ASP070 Co-Chair
810-602-8276
Ted Coon, ASP070 Co-Chair
313-594-2849
Cindy Jiang, Principal Consultant
248-668-3891
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Mike Bzdok, ASP070 Project Manager
248-945-4778
"This material is based upon work supported by the Department of Energy National Energy Technology Laboratory under Award Number DE-FC26-
02OR22910.
This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any
agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy,
completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned
rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily
constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of
authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof."
Questions and Answers
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Great Designs in Steel is Sponsored by:
ArcelorMittal Dofasco, ArcelorMittal USA, Nucor Corporation,
Severstal North America, Inc. and United States Steel Corporation