Solute Enrichment in the Fusion Zone during Resistance Spot Welding of a Third Generation Advanced High Strength Steel

Abstract:

Resistance spot welding is a critical joining technique in automobile assembly. The load carrying properties of spot welds are generally accepted to correlate with weld diameter, which increases with increasing weld current or duration. The formation of a softened layer, or weld halo, surrounding the fusion zone in a spot-welded third generation (Gen3) advanced high strength steel (AHSS) was recently reported in the literature. To optimize weld performance by schedule design, it is necessary to understand the halo formation characteristics and potential impacts. Accordingly, welding of a Gen3 AHSS was performed using weld times between 130 – 1300 ms. Microhardness mapping characterized weld microhardness and the evolution of the halo during welding. Electron probe microanalysis and timeof-flight secondary ion mass spectrometry enabled measurement of solute distributions through the weld halo, while scanning electron microscopy was used for microstructural characterization. The solidified structure was examined using light-optical microscopy, and with the microhardness and compositional data, used to infer the mechanism by which the halo forms during welding. It was found that the halo develops due to solute rejection from a cellular solidification front that advances towards the center of the fusion zone while weld current is applied. Extended weld times increase the size of the weld halo and the solute content of the inner fusion zone. The decrease in weld halo microhardness and the increase in inner fusion zone microhardness is largely explained by the changes in local carbon content associated with halo formation.

• Periodical: Key Engineering Materials (Volume 966)
• Pages: 55-62
• DOI: https://doi.org/10.4028/p-9fYivE
• Online since: November 2023
• Authors: David Marshall*, Caleb Schenck, Lydia Hines, John G. Speer
• Keywords: Fusion Boundary Migration, Gen3 AHSS, Resistance Spot Welding, Weld Halo

References

[1] C. Lesch, N. Kwiaton, and F. B. Klose, "Advanced High Strength Steels (AHSS) for Automotive Applications − Tailored Properties by Smart Microstructural Adjustments," Steel Research International, vol. 88, no. 10, 2017.

DOI: 10.1002/srin.201700210

[2] J.H. Schmitt and T. Iung, "New Developments of Advanced High-Strength Steels for Automotive Applications," Comptes Rendus Physique, vol. 19, no. 8, p.641–656, 2018.

DOI: 10.1016/j.crhy.2018.11.004

[3] D. C. Ramachandran, B. D. N. Figuerdo, and E. Biro, "The Fusion Boundary, A Potential Failure Path in the Resistance Spot Welding of Q&P Steels," in Sheet Metal Welding Conference XIX, Livonia, MI, Nov. 2021.

[4] A. Mohamadizadeh, E. Biro, and M. Worswick, "Shear Band Formation at the Fusion Boundary and Failure Behaviour of Resistance Spot Welds in Ultra-High-Strength Hot-Stamped Steel," Science and Technology of Welding and Joining, vol. 25, no. 7, p.556–563, 2020.

DOI: 10.1080/13621718.2020.1773057

[5] A. Mohamadizadeh, E. Biro, and M. Worswick, "Novel Double-Half Spot Weld Testing Technique For Damage Progress And Failure Analysis Using Digital Image Correlation Techniques," Exp Mech, vol. 61, no. 9, p.1405–1418, 2021.

DOI: 10.1007/s11340-021-00743-4

[6] O. Sherepenko and S. Jüttner, "Transient Softening at the Fusion Boundary in Resistance Spot Welded Ultra-High Strengths Steel 22MnB5 and its Impact on Fracture Processes," Welding in the World, vol. 63, p.151–159, 2019.

DOI: 10.1007/s40194-018-0633-3

[7] O. Sherepenko, A. Mohamadizadeh, A. Zvorykina, M. Worswick, E. Biro, and S. Jüttner, "Determination of Resistance Spot Weld Failure Path in Ultra-High-Strength Press-Hardened Steel by Control of Fusion Boundary Transient Softening," J Mater Sci, vol. 56, no. 25, 2021.

DOI: 10.1007/s10853-021-06165-w

[8] O. Sherepenko, O. Kazemi, P. Rosemann, M. Wilke, T. Halle, and S. Jüttner, "Transient Softening at the Fusion Boundary of Resistance Spot Welds: A Phase Field Simulation and Experimental Investigations for Al–Si-Coated 22MnB5," Metals (Basel), vol. 10, no. 1, 2020.

DOI: 10.3390/met10010010

[9] S. M. Manladan, Y. J. Jang, and Y. Do Park, "Effect of Paint Baking on the Halo Ring and Mechanical Behavior of 30MnB5 Hot-Stamped Steel Resistance Spot Welding Joints," Journal of Materials Research and Technology, vol. 24, p.4756–4761, 2023.

DOI: 10.1016/j.jmrt.2023.04.144

[10] Y. B. Li, D. L. Li, S. A. David, Y. C. Lim, and Z. Feng, "Microstructures of Magnetically Assisted Dual-Phase Steel Resistance Spot Welds," Science and Technology of Welding and Joining, vol. 21, no. 7, p.555–563, 2016.

DOI: 10.1080/13621718.2016.1141493

[11] I. A. Soomro and S. R. Pedapati, "Application of In Situ Post Weld Heat Treatment Using Double Pulse Technology and its Effect on Microstructure and Mechanical Performance of Resistance Spot Welded HSLA350 Steel," International Journal of Advanced Manufacturing Technology, vol. 105, no. 7–8, p.3249–3260, 2019.

DOI: 10.1007/s00170-019-04569-2

[12] B. Figueredo, D. C. Ramachandran, A. Macwan, and E. Biro, "Failure Behavior and Mechanical Properties in the Resistance Spot Welding of Quenched and Partitioned (Q&P) Steels," Welding in the World, vol. 65, no. 12, p.2359–2369, (2021)

DOI: 10.1007/s40194-021-01179-z

[13] X. D. Liu, Y. B. Xu, R. D. K. Misra, F. Peng, Y. Wang, and Y. B. Du, "Mechanical Properties in Double Pulse Resistance Spot Welding of Q&P 980 Steel," J Mater Process Technol, vol. 263, p.186–197, 2019.

DOI: 10.1016/j.jmatprotec.2018.08.018

[14] A. Chabok, H. Cao, E. van der Aa, and Y. Pei, "New Insights into the Fracture Behavior of Advanced High Strength Steel Resistance Spot Welds," J Mater Process Technol, vol. 301, 2022.

DOI: 10.1016/j.jmatprotec.2021.117433

[15] I. Hajiannia, M. Shamanian, M. Atapour, and R. Ashiri, "Evaluation of Weldability and Mechanical Properties in Resistance Spot Welding of Ultrahigh-Strength TRIP1100 Steel," SAE International Journal of Materials and Manufacturing, vol. 12, no. 1, p.5–18, 2018.

DOI: 10.4271/05-12-01-0001

[16] G. Park, K. Kim, S. Uhm, and C. Lee, "A Comparison of Cross-Tension Properties and Fracture Behavior Between Similar and Dissimilar Resistance Spot-Weldments in Medium-Mn TRIP Steel," Materials Science and Engineering A, vol. 752, p.206–216, 2019.

DOI: 10.1016/j.msea.2019.03.023

[17] P. Eftekharimilani, E. M. van der Aa, M. J. M. Hermans, and I. M. Richardson, "Microstructural Characterisation of Double Pulse Resistance Spot Welded Advanced High Strength Steel," Science and Technology of Welding and Joining, vol. 22, no. 7, p.545–554, 2017.

DOI: 10.1080/13621718.2016.1274848

[18] Y. Zhang, W. Xu, G. Zhang, W. Tao, and S. Yang, "Mechanical Behavior and Failure Mechanism of Q&P980 Steel During In Situ Post-Weld Heat Treatment (PWHT) Resistance Spot Welding," Metall Mater Trans A Phys Metall Mater Sci, vol. 53, no. 3, p.794–809, 2022.

DOI: 10.1007/s11661-021-06546-5

[19] M. Stadler, R. Schnitzer, M. Gruber, and C. Hofer, "Improving the Mechanical Performance of a Resistance Spot Welded 1200 MPa TBF Steel," International Journal of Materials Research, vol. 112, p.262–270, 2021.

DOI: 10.1515/ijmr-2020-7962

[20] O. Sherepenko, D. Ramachandran, A. Mohamadizadeh, and E. Biro, "Transient Softening at the Fusion Boundary of Spot Welds in Advanced High-Strength Steels: Dark Horse of the Heat-Affected Zone," in Proceedings of the 61st Conference of Metallurgists, COM 2022, 2023.

DOI: 10.1007/978-3-031-17425-4_9

[21] M. Shamsujjoha, C. M. Enloe, A. C. Chuang, J. J. Coryell, and H. Ghassemi-Armaki, "Mechanisms of Paint Bake Response in Resistance Spot-Welded First and Third Generation AHSS," Materialia, vol. 15, 2021.

DOI: 10.1016/j.mtla.2020.100975

[22] R. Ashiri, S. P. H. Marashi, and Y. D. Park, "Weld Processing and Mechanical Responses of 1-GPa TRIP Steel Resistance Spot Welds," Weld J, vol. 97, no. 5, pp. 157S-169S, 2018.

DOI: 10.29391/2018.97.014

[23] E. C. Bain, Functions of the Alloying Elements in Steel. Cleveland: ASM International, 1939.

[24] H. T. Lee and Y. C. Chang, "Effect of Double Pulse Resistance Spot Welding Process on 15B22 Hot Stamped Boron Steel," Metals (Basel), vol. 10, no. 10, p.1–17, 2020.

DOI: 10.3390/met10101279

[25] F. Krajcarz, A. F. Gourgues-Lorenzon, and E. Lucas, "Influence of Carbon Content on the Primary Solidification Mode of High Strength Steels in Resistance Spot Welding Conditions," Scr Mater, vol. 120, p.98–102, 2016.

DOI: 10.1016/j.scriptamat.2016.04.011

[26] F. Rossillon, A. Galtier, J. Robert, M. Duchet, A. Lens, and H. Oikawa, "Effect of Welding Cycle on the Fatigue Behaviour of Resistance Spot Welded Dual Phase Steels," Welding in the World, vol. 52, no. 11, p.30–41, 2008.

DOI: 10.1007/bf03266680

[27] F. Krajcarz, A. F. Gourgues, V. Bochard, E. Lucas, and M. Bobadilla, "Formation et Solidification de la Zone Fondue en Soudage Par Point : Influence des Paramètres de Soudage," in Materiaux 2010, Nantes, France, Oct. 2010.

[28] D. C. Ramachandran, B. Figueredo, O. Sherepenko, W. Jin, Y. Do Park, and E. Biro, "A Study on Improving the Mechanical Performance by Controlling the Halo Ring in the Q&P 980 Steel Resistance Spot Welds," J Manuf Process, vol. 75, p.320–330, 2022.

DOI: 10.1016/j.jmapro.2022.01.019