Tensile–Shear Fracture Behavior Prediction of High-Strength Steel Laser Overlap Welds
Abstract
:1. Introduction
2. Experimental Procedure
3. Results and Discussion
3.1. Laser Weld Characteristics under Various Welding Conditions
3.2. Fracture Mode Definitions for Overlap Welds
3.3. Estimation of Hardness with Carbon Equivalent
3.4. Critical Interface Bead Width (LIF)
4. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
BM | base metal |
WM | metals-08-00365 |
HAZ | weld metal |
IF | interface fracture |
DIC | digital image correlation |
tensile load on BM | |
tensile stress on BM | |
tensile load on HAZ | |
tensile stress on HAZ | |
shear load on the IF | |
shear stress on IF | |
θ | angle of the rotation |
width of the specimen | |
thickness of the specimen | |
measured interface bead width | |
critical bead width to change the fracture mode | |
carbon equivalent proposed in [21] | |
predicted hardness value of WM | |
predicted hardness value of HAZ | |
as received tensile strength of the BM | |
calculated tensile strength of the HAZ | |
calculated tensile strength of the WM | |
calculated shear strength of WM |
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Base Materials | C | Si | Mn | P | S | Cr | B |
---|---|---|---|---|---|---|---|
590 DP (1.2 mm) | 0.078 | 0.363 | 1.808 | 0.011 | 0.001 | - | - |
780 DP (1.2 mm) | 0.070 | 0.977 | 2.264 | 0.010 | 0.015 | - | - |
980 DP (1.2 mm) | 0.170 | 1.340 | 2.000 | 0.016 | 0.001 | - | - |
1180 CP (1.2 mm) | 0.110 | 0.110 | 2.790 | 0.019 | 0.004 | 1.040 | - |
1500 HPF (1.1 mm) | 0.216 | 0.240 | 1.255 | 0.002 | 0.002 | 0.001 | 0.003 |
(a) | ||
Specimen. | Top Plate | Top Plate |
S6/6 | CR 590 DP | CR 590 DP |
S8/8 | CR 780 DP | CR 780 DP |
S10/10 | CR 980 DP | CR 980 DP |
S12/12 | CR 1180 CP | CR 1180 CP |
S15/15 | HPF 1500 | HPF 1500 |
(b) | ||
Specimen. | Top Plate | Bottom Plate |
D6/8 | CR 590 DP | CR 780 DP |
D6/10 | - | CR 980 DP |
D6/12 | - | CR 1180 CP |
D6/15 | - | HPF 1500 |
D8/10 | CR 780 DP | CR 980 DP |
D8/12 | - | CR 1180 CP |
D8/15 | - | HPF 1500 |
D10/12 | CR 980 DP | CR 1180 CP |
D10/15 | - | HPF 1500 |
D12/15 | CR 1180 CP | HPF 1500 |
Parameters | Level 1 | Level 2 | Level 3 | Level 4 | Level 5 | Level 6 |
---|---|---|---|---|---|---|
Focal position (mm) | 0 | 5 | 10 | 10 | 15 | 20 |
Laser spot size (mm) | 0.3 | 0.34 | 0.46 | 0.46 | 0.55 | 0.65 |
Apparent power density (W/mm2) | 13,440 | 10,463 | 5716 | 5716 | 3999 | 2863 |
Welding speed (mm/s) | 70 | 60 | 48 | 37 | 26 | 20 |
Heat input per unit length (J/mm) | 54.3 | 63.3 | 79.2 | 102.7 | 146.2 | 190.0 |
(a) | ||||||||||
Specimen | S6/6 | S8/8 | S10/10 | S12/12 | S15/15 | |||||
Measured hardness (Hv) | 390.0 | 388.8 | 480.0 | 399.9 | 492.7 | |||||
Predicted hardness (Hv) | 391.4 | 407.1 | 475.0 | 431.0 | 499.7 | |||||
CELB | 0.157 | 0.180 | 0.277 | 0.214 | 0.312 | |||||
Error (%) | 0.4 | 4.7 | 1.0 | 7.8 | 1.4 | |||||
(b) | ||||||||||
Specimen | D6/8 | D6/10 | D6/12 | D6/15 | D8/10 | D8/12 | D8/15 | D10/12 | D10/15 | D12/15 |
Measured hardness (Hv) | 386.6 | 432.2 | 390.4 | 434.0 | 429.4 | 396.4 | 445.6 | 446.0 | 478.4 | 442.2 |
Predicted hardness (Hv) | 399.3 | 433.2 | 411.2 | 445.5 | 441.1 | 419.0 | 453.4 | 453.0 | 487.4 | 465.3 |
Error (%) | 3.3 | 0.2 | 5.3 | 2.6 | 2.7 | 5.7 | 1.8 | 1.6 | 1.9 | 5.2 |
(a) | ||||||||||
Phase fraction | Hm | Hb | Hf | Vm | Vb | Vfp | ||||
590 DP | 357.95 | 290.27 | 151.67 | 0.44 | 0.06 | 0.50 | ||||
780 DP | 371.86 | 292.97 | 125.34 | 0.47 | 0.03 | 0.50 | ||||
980 DP | 473.84 | 337.26 | 117.19 | 0.55 | 0.02 | 0.43 | ||||
1180 CP | 383.16 | 321.56 | 201.17 | 0.53 | 0.01 | 0.46 | ||||
1500 HPF | 479.80 | 349.89 | 173.57 | 0.54 | 0.04 | 0.42 | ||||
(b) | ||||||||||
Base metal | 590 DP | 780 DP | 980 DP | 1180 CP | 1500 HPF | |||||
Measured hardness (Hv) | 264.2 | 252.2 | 286.8 | 299.7 | 303.6 | |||||
Predicted hardness (Hv) | 250.2 | 247.2 | 317.7 | 298.2 | 345.8 | |||||
Error (%) | 5.3 | 2.0 | 10.8 | 0.5 | 13.9 |
(a) Similar Material Combination | ||||||||||
Specimen | S6/6 | S8/8 | S10/10 | S12/12 | S15/15 | |||||
609.0 | 816.5 | 1023.3 | 1272.7 | 1545.0 | ||||||
817.4 | 807.4 | 1037.8 | 974.0 | 1129.5 | ||||||
738.2 | 767.8 | 895.9 | 812.9 | 942.4 | ||||||
(b) Dissimilar Material Combinations | ||||||||||
Specimen | D6/8 | D6/10 | D6/12 | D6/15 | D8/10 | D8/12 | D8/15 | D10/12 | D10/15 | D12/15 |
609.0 | 816.5 | 1023.3 | 1272.7 | |||||||
817.4 | 807.4 | 1037.8 | 974.0 | |||||||
753.1 | 817.0 | 775.5 | 840.2 | 831.9 | 790.4 | 855.1 | 854.4 | 919.2 | 877.6 |
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Kang, M.; Jeon, I.-H.; Han, H.N.; Kim, C. Tensile–Shear Fracture Behavior Prediction of High-Strength Steel Laser Overlap Welds. Metals 2018, 8, 365. https://doi.org/10.3390/met8050365
Kang M, Jeon I-H, Han HN, Kim C. Tensile–Shear Fracture Behavior Prediction of High-Strength Steel Laser Overlap Welds. Metals. 2018; 8(5):365. https://doi.org/10.3390/met8050365
Chicago/Turabian StyleKang, Minjung, In-Hwan Jeon, Heung Nam Han, and Cheolhee Kim. 2018. "Tensile–Shear Fracture Behavior Prediction of High-Strength Steel Laser Overlap Welds" Metals 8, no. 5: 365. https://doi.org/10.3390/met8050365