Materials Transactions, Vol.52 No.01 (2011) pp.8-11
© 2011 The Japan Institute of Metals

Dynamic Strain Induced Transformation of Austenite to Ferrite during High Temperature Extrusion of Low Carbon Steel

M. Shaban, S. Gozalzadeh and B. Eghbali

Ultra fine grained materials exhibit superior mechanical properties compared with the conventional coarse grained one. In the present work, the hot extrusion process was conducted on plain low carbon steel to achieve ultra fine ferritic structure. At first, with the aid of 3D finite element simulation an appropriate preheating temperature for the initiation of dynamic strain induced transformation of austenite to ferrite was predicted to be 930°C. After hot extrusion, the results of microstructural analysis by optical microscopy showed that the predicted temperature was suitable. Extruded samples showed ultra fine ferrite structure with average grain size of 1 μm on a plane perpendicular to material flow. Also, the microstructural developments with strain in the extrusion zone confirmed the occurrence of dynamic strain induced transformation of austenite to ferrite during deformation process. Tensile strength of processed steel is two times higher than coarse grained one.

(Received 2010/8/30; Accepted 2010/10/19; Published 2010/12/25)

Keywords: ultra fine ferrite (UFF) steel, dynamic strain induced transformation (DSIT), hot extrusion, finite element method (FEM)

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REFERENCES

1. F. B. Pickering: Physical metallurgy and the design of steels, (Applied Science Publishers, London, UK, 1978).
2. K. F. Al-Hajeri: The Grain Coarsening and Subsequent Transformation of Austenite in the HSLA Steel during High Temperature Thermomechanical Processng, (University of Pittsburgh, 2005) pp.15–16.
3. T. Tanaka: Science and Technology of Hot Rolling Process of Steel, Microalloying `95, Pittsburgh, (ISS, 1995) pp.165–181.
4. D. T. Llewellyn: Steels: Metallurgy and Applications, (Butterworth-Heinemann Reading, 1992) pp.64–122.
5. M. Cohen and S. S. Hansen: On the Fundamentals of HSLA Steels, HSLA Steels: Metallurgy and Applications, Conference Proceeding, (ASM International, Beijing, China, 1986) pp.61–71.
6. J. M. Gray and A. J. DeArdo: Austenite Conditioning Alternatives for Microalloyed Steels Products, HSLA Steels: Metallurgy and Applications, Conference Proceeding, (ASM International, Beijing, China, 1986) pp.83–96.
7. E. J. Palmiere, C. I. Garcia and A. J. DeArdo: Metall. Mater. Trans. A 25 (1994) 277.
8. R. Priestner and P. D. Hodgson: Mater. Sci. Technol. 8 (1992) 849.
9. P. D. Hodgson, M. R. Hickson and R. K. Gibbs: Mater. Sci. Forum 284 (1998) 63.
10. P. J. Hurley, B. C. Muddle and P. D. Hodgson: Metall. Mater. Trans. A 33 (2002) 2985.
11. H. Beladi, G. L. Kelly, A. Shokouhi and P. D. Hodgson: Mater. Sci. Eng. A 371 (2004) 343.
12. R. Priestner and A. K. Ibraheem: Mater. Sci. Technol. 16 (2000) 1267.
13. G. Azevedo, R. Barbosa, E. V. Pereloma and D. B. Santos: Mater. Sci. Eng. A 402 (2005) 98.
14. H. Beladi, G. L. Kelly, A. Shokouhi and P. D. Hodgson: Mater. Sci. Eng. A 367 (2004) 152.
15. H. Yada, C.-M. Li and H. Yamagata: ISIJ Int. 40 (2000) 200.
16. E. Yu Tonkov and E. G. Ponyatovsky: Phase Transformations of Elements Under High Pressure, (CRC press, 2005) pp.253–265.
17. S. J. Xie, P. K. Liaw and H. Choo: J. Mater. Sci. 41 (2006) 6328.

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