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Licensed Unlicensed Requires Authentication Published by De Gruyter May 28, 2019

Mechanical properties characterization of resistance spot welded DP1000 steel under uniaxial tensile tests

Ehsan Javaheri, Andreas Pittner, Benjamin Graf and Michael Rethmeier
From the journal Materials Testing

Abstract

Resistance spot welding (RSW) is widely used in the automotive industry as the main joining method. Generally, an automotive body contains around 2000 to 5000 spot welds. Therefore, it is of decisive importance to characterize the mechanical properties of these areas for the further optimization and improvement of an automotive body structure. The present paper aims to introduce a novel method to investigate the mechanical properties and microstructure of the resistance spot weldment of DP1000 sheet steel. In this method, the microstructure of RSW of two sheets was reproduced on one sheet and on a bigger area by changing of the welding parameters, e. g. welding current, welding time, electrode force and type. Then, tensile tests in combination with digital image correlation (DIC) measurement were performed on the notched tensile specimens to determine the mechanical properties of the weld metal. The notch must be made on the welded tensile specimen to force the fracture and elongation on the weld metal, enabling the characterization of its properties. Additionally, the parameters of a nonlinear isotropic material model can be obtained and verified by the simulation of the tensile specimens. The parameters obtained show that the strength of DP1000 steel and the velocity of dislocations for reaching the maximum value of strain hardening, are significantly increased after RSW. The effect of sample geometry and microstructural inhomogeneity of the welded joint on the constitutive property of the weld metal are presented and discussed.


*Correspondence Address, M.Sc. Ehsan Javaheri, Füge- und Beschichtungstechnik, Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK, Pascalstraße 8-9, 10587 Berlin, Germany, E-mail:

Ehsan Javaheri studied Computational Sciences in Engineering at the Technische University in Braunschweig, Germany, and now works as a Scientific Assistant at the Fraunhofer IPK in Berlin, Germany.

Dr.-Ing. Andreas Pittner studied Computational Engineering in 2007 at the Stralsund University of Applied Sciences in Stralsund, Germany and has been the Head of the “Arc Welding and Simulation Department” at the Federal Institute for Materials Research and Testing (BAM) in Berlin, Germany since 2011.

Dr.-Ing. Benjamin Graf studied Mechanical Engineering at the Technical University Berlin, with a focus on power engines and machines. After his studies, he started working at the Fraunhofer IPK, Berlin in 2010. His technological field of interest comprises laser metal deposition and its applications in wear protection, repair and additive manufacturing. He is Head of the Department of “Joining Technology” at the Fraunhofer IPKin Berlin, Germany.

Prof. Dr.-Ing. Michael Rethmeier, born 1972, studied Mechanical Engineering at the Technical University in Braunschweig, Germany. Afterwards, he worked at the same university where he received his Ph.D. in 2003. He became Project Manager for production engineering and concepts at the Volkswagen AG group research. In 2007 he received his Full Professorship at the Technical University of Berlin in combination with being Head of the Division “Safety of Joined Components” at the Federal Institute for Materials Research and Testing (BAM) in Berlin. Additionally, he is the Division Director of “Joining and Coating Technology” at the Fraunhofer Institute for Production Systems and Design Technology IPK in Berlin, Germany.


References

1 A.Ramazani, K.Mukherjee, A.Abdurakhmanov, M.Abbasi and U.Prahl: Characterization of Microstructure and Mechanical Properties of Resistance Spot Welded DP600 Steel, Metals5 (2015), No. 3, pp. 1704171610.3390/met5031704Search in Google Scholar

2 D.Cornette, T.Hourman, O.Hudin, J.Laurent and A.Reynaert: High Strength Steels for Automotive Safety Parts, SAE Transactions Journal of Materials & Manufacturing (2001) 10.4271/2001-01-0078Search in Google Scholar

3 E.Javaheri, K.Hemmesi, P.Tempel and M.Farajian: Fatigue assessment of the welded joints containing process relevant imperfections, Welding in the world (2018)10.1007/s40194-018-00676-ySearch in Google Scholar

4 F.Nikoosohbat, S.Kheirandish, M.Goodarzi and P.Marashi: Microstructure and failure behaviour of resistance spot welded DP980 dual phase steel, Materials Science and Technology26 (2010), No. 6, pp. 73874410.1179/174328409X414995Search in Google Scholar

5 G.Weber, S.Brauser, H.Gaul and M.Rethmeier: Study of Fatigue Behavior for Spot Welded Tensile Shear Specimens of Advanced High Strength Steels, Steel research international83 (2012), No. 10, pp. 98899410.1002/srin.201100286Search in Google Scholar

6 M.Pouranvari and S. P. H.Marashi: Key factors influencing mechanical performance of dual phase steel resistance spot welds, Science and Technology of Welding and Joining15 (2010), No. 2, pp. 14915510.1179/136217109X12590746472535Search in Google Scholar

7 C.Sawanishi, T.Ogura, K.Taniguchi, R.Ikeda, K.Oi, K.Yasuda and A.Hirose: Mechanical properties and microstructures of resistance spot welded DP980 steel joints using pulsed current pattern, Science and Technology of Welding and Joining19 (2014), No. 1, pp. 525910.1179/1362171813Y.0000000165Search in Google Scholar

8 K. W.Ewing, M.Cheresh, R.Thompson and P.Kukuchek: Static and Impact Strengths of Spot-Welded HSLA and Low Carbon Steel Joints, SAE Technical Paper 820281 (1982) 10.4271/820281Search in Google Scholar

9 S.Dancette, V.Massardier-Jourdan, D.Fabregue, J.Merlin, T.Dupuy and M.Bouzerkri: HAZ Microstructures and Local Mechanical Properties of High Strength Steels Resistance Spot Welds, ISIJ International51 (2011), No. 1, pp. 9910710.2355/isijinternational.51.99Search in Google Scholar

10 X.Kong, Q.Yang, B.Li, G.Rothwell, R.English and X. J.Ren: Numerical study of strengths of spot-welded joints of steel, Materials and Design29 (2008), No. 8, pp. 1554156110.1016/j.matdes.2007.12.001Search in Google Scholar

11 F.Orth, W.Peterson, S. S.Babu and Y. P.Yang: Integrated computational model to predict mechanical behaviour of spot weld, Science and Technology of Welding and Joining13 (2008), No. 3, pp. 23223910.1179/174329308X283901Search in Google Scholar

12 V.Hernandez, S. KumarPand, Y.Okita and N. Y.Zhou: A study on heat affected zone softening in resistance spot welded dual phase steel by nanoindentation, Journal of Materials Science45 (2010), No. 6, pp. 1638164710.1007/s10853-009-4141-0Search in Google Scholar

13 SEP 1220-2:2011-08: Prüf- und Dokumentationsrichtlinie für die Fügeeignung von Feinblechen aus Stahl – Teil 2: Widerstandspunktschweißen, Beuth Verlag, Berlin (2011)Search in Google Scholar

14 A. P.Reynolds and F.Duvall: Digital Image Correlation for Determination of Weld and Base Metal Constitutive Behavior, Welding Research Supplement (1999), pp. 355360Search in Google Scholar

15 DIN EN ISO 5821:2010–04: Widerstandsschweißen – Punktschweiß-Elektrodenkappen, Beuth Verlag, Berlin (2010)Search in Google Scholar

16 DIN 50125:2009–07: Testing of metallic materials – Tensile test pieces, Beuth Verlag, Berlin (2009)Search in Google Scholar

17 Z.Zhang, M.Hauge, C.Thaulow and J.Degard: A notched cross weld tensile testing method for determining true stress–strain curves for weldments, Engineering Fracture Mechanics69 (2002), No. 3, p. 35336610.1016/S0013-7944(01)00075-3Search in Google Scholar

18 M.Biegler, B.Graf and M.Rethmeier: In-situ distortions in LMD additive manufacturing walls can be measured with digital image correlation and predicted using numerical simulations, Additive Manufacturing20 (2018), pp. 10111010.1016/j.addma.2017.12.007Search in Google Scholar

19 J.Lemaitre and J. L.Chaboche: Mechanics of solid materials, Cambridge university press Cambridge, United Kingdom (1990)10.1017/CBO9781139167970Search in Google Scholar

20 N.Zhong, X.Liao, M.Wang, Y.Wu and Y.Rong: Improvement of microstructures and mechanical properites of resistance spot welded DP600 steel by double pulse technology, materials transactions52 (2011), No. 12, pp. 2143215010.2320/matertrans.M2011135Search in Google Scholar

21 D.Zhao, Y.Wang, L.Zhang and P.Zhang: Effects of Electrode Force on Microstructure and Mechanical Behavior of the Resistance Spot Welded DP600 Joint, Materials and Design50 (2013), pp. 727710.1016/j.matdes.2013.02.016Search in Google Scholar

22 DIN EN ISO 6507-1:2018-07: Metallische Werkstoffe – Härteprüfung nach Vickers – Teil 1: Prüfverfahren (ISO 6507-1:2018), Beuth Verlag, Berlin (2018)Search in Google Scholar

23 M.Naderi, M.Ketabchi, M.Abbasi and W.Bleck: Analysis of microstructure and mechanical properties of different high strength carbon steels after hot stamping, Journal of Materials Processing Technology211 (2011), No. 6, pp. 1117112510.1016/j.jmatprotec.2011.01.015.Search in Google Scholar

Published Online: 2019-05-28
Published in Print: 2019-06-01

© 2019, Carl Hanser Verlag, München