Development of an Ultrafine Grained Ferrite in a Low C-Mn Steel Intensely Deformed under Hot Torsion

Abstract:

In the last years, several studies concerning ultra refinement of ferrite grains have been conducted using different experimental techniques (ECAP, ARB, HPT). The aim of all investigations was to provide an optmized relationship between mechanical properties and microstructure of steels. The present work, likewise, deals with strain induced dynamic transformation of ferrite. Samples of low C-Mn steel were intensely deformed in hot torsion aiming at the production of ultrafine grains of ferrite thereby enhancing the mechanical properties when compared to hot rolled products. After soaking during 5min at 900°C, the samples were quenched and then reheated and submitted to hot torsion deformation at temperatures of 700 and 740°C. The torsion schedule consisted of 7 isothermal passes leading to a total strain of ≈1, generating an ultrafine microstructure with grain sizes of the order of 1µm. The shape of stress-strain curves so obtained suggested that ferrite refinement occurred by dynamic recrystallization. The various constituents present in the microstructure as well as ferrite grain size and morphology were examined by optical and scanning electron microscopy. Microhardness tests were performed to evaluate mechanical properties.

• Periodical: Materials Science Forum (Volumes 467-470)
• Pages: 1271-1276
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.467-470.1271
• Online since: October 2004
• Authors: G. Azevedo, Ronaldo Barbosa, Dagoberto Brandão Santos
• Keywords: Strain Induced Transformation, Torsion Testing, Ultra-Fine Ferrite

References

[1] R. Z . Valiev, A.V. Korznikov, R.R. Mulyukov, Mat. Sci. & Eng. A, Vol. A168, n. 2 (August 1993), pp.141-148.

[2] Y. Saito, H. Utsunomiya, N. Tsuji, T. Sakai, Acta Mat., Vol. 47, n. 2, (January 1999), pp.579-583.

[3] R. Ueji, N. Tsuji, Y. Saito, Y. Minamino, ISUGS 2001, pp.222-225.

[4] P. C. M Rodrigues, R. K. Brzuszek, D. B. Santos, ISUGS 2001, pp.138-141.

[5] P.J. Hurley, B.C. Muddle, P.D. Hodgson, Met. and Mat. Trans. A, Vol. 33A, 9 (September 2002), pp.2985-2993.

[6] J.W. Bowden, F.H. Samuel, J.J. Jonas, Met. and Mat. Trans. A, Vol. 22A, (Dec. 1991) pp.947-2957.

[7] L.N. Pussegoda, J.J. Jonas, ISIJ International, Vol. 31, N. 3, (1991), pp.278-288.

[8] L.P. Karjalainen, T.M. Maccagno, J.J. Jonas, ISIJ International, Vol. 35, nº12 (1995) pp.1523-1531.

[9] A.B. Cota, R. Barbosa and D.B. Santos, Journal of Mat. Proc. Techn. Vol. 100, 1-3, (April 2000), pp.156-162.

[10] S.B. Davenport, D.N. Hanlon, S. Van Der Zwaag, Scripta Mat., Vol. 46 (2002), pp.413-417.

[11] K.W. Andrews, JISI, vol. 203, pp.721-727, (1965).

[12] S. Takaki, K. Kawasaki, Y. Kimura, Journal of Mat. Proc. Technology, Vol. 117, 3 (November 2001), pp.359-363.

[13] T. Hayashi, M. Saito, K. Tsuzaki, K. Nagai, 4th International Conference On Recrystallization And Related Phenomena (Rex99). Conference Proceedings. The Japan Institute of Metals (1999), pp.333-338.

[14] N. Tsuji, R. Ueji, Y. Minamino, Y. Saito, Scripta Mat., Vol. 46, 4 (February 2002), pp.305-310.

[15] Y. Adachi, S. Hinotani, Thermec 2000. Las Vegas, USA, (December 2000), pp.77-82.

[16] Y.D. Huang, W.Y. Yang, Z.Q. Sun, Journal of Mat. Proc. Tech. Vol. 134, 1, (March 2003), pp.19-25.

[17] X.D. Liu, J. K. Solberg, R.E. Gjengedal, A.O. Kluken, Journal of Mat. Proc. Techn. Vol. 45, 1-4 (September 1994), pp.497-502.

[18] S.L. Semiatin, G.D. Lahoti, J.J. Jonas, ASM Metals Handbook. Vol. 8 (Mechanical Testing), 9th Edition, American Society For Metals, Metals Park, Ohio (1985), pp.154-184.

[19] G.L. Kelly, P.D. Hodgson, 42nd MWSP Conf. Proceedings, Vol. 38 (2000), pp.515-522.