Skip to main content
SpringerLink
Log in

Transient softening at the fusion boundary in resistance spot welded ultra-high strengths steel 22MnB5 and its impact on fracture processes

  • Research Paper
  • Published:
Welding in the World Aims and scope Submit manuscript

Abstract

This work gives an insight in the transient softening at the fusion boundary of resistance spot welds of hot stamped steel 22MnB5. The development of the softened region was investigated for three different energy input concepts with short, middle, and long welding times; thereby, an experimental technique of interrupted spot welds combined with metallographic investigations and hardness measurements was employed. The observed softening can be explained with the effect of carbon segregation, supported by the diffusional γ → δ phase transformation or delta-ferrite nucleation from the liquid L → δ, which may lead to formation of δ-Fe at the fusion boundary. Subsequent quenching at cooling speeds of about 2500 °C/s after the welding process prevents carbon redistribution and decomposition of δ-Fe. This assumption is in good agreement with the results of carbon measurement at the fusion boundary and metallographic observations. The influence of the softened region on fracture of resistance spot welds was investigated, using cross-tension test and metallographic analysis. The transition of the fracture mode from fracture through the weld nugget for short welding time to fracture along the fusion boundary for long and middle welding times is observed. Marginally higher maximal force and energy absorption by welded joints with long welding times was observed.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14
Fig. 15

Similar content being viewed by others

References

  1. Specification for automotive weld quality—resistance spot welding of steel D8.1M: 2007. Miami, FL

  2. Saha DC, Ji CW, Park YD (2015) Coating behaviour and nugget formation during resistance welding of hot forming steels. Sci Technol Weld Join 20(8):708–720

    Article  Google Scholar 

  3. Rosner M. Kleben von verzinktem presshärtenden Stahl. In: DVS Media GmbH (Hrsg.): DVS Congress 2015. Grosse Schweisstechnische Tagung: DVS-Studentenkongress: Fügen von faserverstärkten Kunststoffen, anwendungsnahe Schweisssimulation, Schulung und Prüfung im DVS: IBESS - Forschungscluster "Bruchmechanik" : Vorträge der gleichnamigen Tagung im Rahmen von DVS Congress und DVS Expo in Nürnberg vom 15. bis 17. September 2015. Düsseldorf 2015

  4. Cho YJ, Chang IS, Lee HB (2008) Advanced resistance spot welding technologies. New machine, adaptive control and fem simulation. Mater Sci Forum 580–582:367–370

    Article  Google Scholar 

  5. Baryliszyn P (2015) Widerstandspunktschweißen für große Bauteiltoleranzen: TUDpress. Dresden

  6. Schuster, L.; Sommer, S.: Characterization and modelling of soft zones around spot welds in high strength steels: proceedings of the 5th international conference on steels in cars and trucks steels in cars and trucks 2017 2017

    Google Scholar 

  7. Jong Y-S, Lee Y-K, Kim D-C, Kang M-J, Hwang I-S, Lee W-B (2011) Microstructural evolution and mechanical properties of resistance spot welded ultra high strength steel containing boron. Mater Trans 52(6):1330–1333

    Article  Google Scholar 

  8. Eller TK (2016) Modeling of tailor hardened boron steel for crash simulation: University of Twente. Enschede

  9. Li YB, Li DL, David SA, Lim YC, Feng Z (2016) Microstructures of magnetically assisted dual-phase steel resistance spot welds. Sci Technol Weld Join 21(7):555–563

    Article  Google Scholar 

  10. Sherepenko O, Jüttner S. Schweißtechnische Verarbeitung höchstfester Stähle. Widerstandspunktschweißen unter Berücksichtigung fertigungs-bedingter Spalte: 34. Assistentenseminar Füge- und Schweißtechnik. Vorträge der gleichnamigen Veranstaltung in Lichtenwalde vom 26. bis 28. September 2013. Düsseldorf 2014

  11. Karbasian H, Tekkaya AE (2010) A review on hot stamping. J Mater Process Technol 210(15):2103–2118

    Article  Google Scholar 

  12. Wink H-J, Krätschmer M (2012) Charakterisierung und Modellierung des Bruchverhaltens von Punktschweißverbindungen in pressgehärteten Stählen. Teil II - Simulation des Schweißens. Ulm

  13. Harlin N, Jones TB, Parker JD (2002) Weld growth mechanisms during resistance spot welding of two and three thickness lap joints. Sci Technol Weld Join 7(1):35–41

    Article  Google Scholar 

  14. Geslain E, Rogeon P, Pierre T, Pouvreau C, Cretteur L (2018) Coating effects on contact conditions in resistance spot weldability. J Mater Process Technol 253:160–167

    Article  Google Scholar 

  15. Brandes EA, Brook GB, Smithells CJ (1998) Smithells metals reference book, 7th ed / edited by E.A. Brandes and G.B. Brook: Butterworth-Heinemann. Oxford, Boston

Download references

Funding

The authors would like to acknowledge the province Saxony-Anhalt for financial support of the study in the framework of the postgraduates funding and thank all the students and colleagues, who have contributed their effort to the investigations.

Author information

Authors and Affiliations

  1. Institute of Materials and Joining Technology, Otto von Guericke University Magdeburg, Magdeburg, Germany

    Oleksii Sherepenko & Sven Jüttner

Authors
  1. Oleksii Sherepenko
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Sven Jüttner
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Oleksii Sherepenko.

Additional information

Recommended for publication by Commission III - Resistance Welding, Solid State Welding, and Allied Joining Process

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Sherepenko, O., Jüttner, S. Transient softening at the fusion boundary in resistance spot welded ultra-high strengths steel 22MnB5 and its impact on fracture processes. Weld World 63, 151–159 (2019). https://doi.org/10.1007/s40194-018-0633-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s40194-018-0633-3

Keywords

Search

Navigation