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The Role of Niobium in Cold Rolled TRIP Steel

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Abstract:

In the recent years several new high strength steel grades have been developed, which exhibit improved cold formability and thus are especially suitable for the car body. These multi-phase steels have to be processed via continuous annealing lines. The best combination of strength and uniform elongation is obtained with ferrite-bainite-retained austenite multiphase steel, which rely on transformation induced plasticity (TRIP effect) during the cold forming operation. The production route for TRIP steel, which relies on two isothermal heat treatments, is explained as well as the role of the major alloying elements. In order to optimize the property combinations, microalloying with niobium is a successful means. Niobium increases the strength of the steel with 15 MPa per 0.01 %Nb and simultaneously provides also a higher amount of stable austenite, thus guaranteeing both, increased strength and formability. The metallurgical background for providing these results is explained. Even though the amount of high strength steel in automobiles is continuously increasing, the application of TRIP steel is still limited. However, the good experience in trials and first successful applications make an increased usage of this steel type also realistic, despite its relatively high production costs and reduced weldability.

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Periodical:

Materials Science Forum (Volumes 473-474)

Pages:

91-102

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.473-474.91

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Online since:

January 2005

Authors:

Klaus Hulka

Keywords:

Microstructure, Niobium Microalloying, Retained Austenite, TRIP Effect

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© 2005 Trans Tech Publications Ltd. All Rights Reserved

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References

[1] G. Hartmann, W. Müschenborn, C. Schneider and R. Simon, Neue Entwicklungen in der Blechumformung, DGM Verlag, Oberursel (Germany), 1996, p.1.

Google Scholar

[2] W. Bleck, A. Frehn and J. Ohlert, Niobium in dual phase and TRIP steel, Proc. of Int. conference Niobium 2001, Orlando (Fl), in print.

Google Scholar

[3] W. Bleck, Using the TRIP effect-the dawn of a promising group of cold formable steels, TRIP aided high strength ferrous alloys, GRIPS, Bad Harzburg (Germany), pp.13-22.

Google Scholar

[4] Y. Sakuma, O. Matsumura and H. Takechi, Met. Trans. A, 22A, 1991, pp.489-498.

Google Scholar

[5] S. Traint, A. Pichler, K. Spiradek-Hahn, K. Hulka and E. Werner, MWSP conference 2003, TMS publication in print.

Google Scholar

[6] L. Meyer, H.E. Bühler and F. Heisterkamp, Thyssenforschung 3, 1971, No 1+2, pp.8-43.

Google Scholar

[7] L. Meyer, Optimisation of material properties in the production of hot and cold rolled steel sheet, Verlag Stahleisen, Düsseldorf (Germany), (1988).

Google Scholar

[8] E.J. Drewes and B. Engl, Stahl und Eisen 108 (1988), p.987.

Google Scholar

[9] K. Hulka, W. Bleck and K. Papamantellos, Relationships between heat treatment conditions, microstructure and properties of niobium microalloyed TRIP steels, Proc. of 41st mechanical working and steel processing conference, ISS, Warrendale (Pa), 1999, pp.67-77.

Google Scholar

[10] J. Ohlert, W. Bleck and K. Hulka, Control of Microstructure in TRIP steel by niobium, TRIP aided High strength ferrous alloys, GRIPS, Bad Harzburg (Germany), pp.199-206.

Google Scholar

[11] www. ulsab. avc. org.

Google Scholar

[12] M. Imagumbai, CBMM Asia, personal information (2001).

Google Scholar