MICROSTRUCTURAL EVOLUTION AND MECHANICAL PERFORMANCE OF RESISTANCE SPOT WELDED DP1000 STEEL WITH SINGLE AND DOUBLE PULSE WELDING

1 CHABOK Ali
Co-authors:
2 VAN DER AA Ellen 3 DE HOSSON Jeff 1 PEI Yutao
Institutions:
1 Department of Advanced Production Engineering, Engineering and Technology Institute Groningen, University of Groningen, Nijenborgh 4, 9747 AG, the Netherlands
2 Tata Steel, P.O. Box 1000, 1970 CA IJmuiden, the Netherlands
3 Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Conference:
26th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 24th - 26th 2017
Proceedings:
Proceedings 26th International Conference on Metallurgy and Materials
Pages:
678-683
ISBN:
978-80-87294-79-6
ISSN:
2694-9296
Published:
9th January 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
27 views / 4 downloads
Abstract

Two welding schemes of single and double pulse were used for the resistance spot welding of DP1000 dual phase steel. The changes in the mechanical performance and variant pairing of martensite under two different welding conditions were scrutinized. It is demonstrated that, although both welds fail in pull-out failure mode, double pulse welding enhances cross-tension strength and energy absorption capability of the weld compared to single pulse welding process. Double pulse welding effectively changes the microstructure of the fusion zone. While the fusion zone of single pulse welds has a typical microstructure of columnar grains, the initial fusion zone of double pulse welds is subdivided into two zones: the outer recrystallized layer composing of martensitic microstructure formed within the equiaxed prior austenite grains, and the inner part of columnar grains resulted from the rapid solidification process of resistance spot welding. Orientation imaging microscopy results show that the recrystallized layer of double pulse welds exhibits a lower fraction of high-angle grain boundaries and coarse structure of Bain groups.

Keywords: Dual phase steel; Resistance spot welding; Cross-tension test; Orientation imaging microscopy.
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