The Activation Energy of Superplastic Flow above the Critical Temperature for Steel CrWMn

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Abstract:

By means of superplastic tensile test above the Ac1 temperature (γ→α transformation temperature), superplastic deformation activation energy of ultrafine-grained commercial die steel CrWMn is investigated on the basis of the Arrhenius theory equation, exp( / ) 1 ε& = Aσ m −Q RT , which indicates the resistance of the superplastic deformation. According to the Arrhenius equation, the activation energy is estimated from the log σt vs 1/T relationship at a constant of sensitivity index of strain rate. The results show that the strain rate sensitivity index is a constant and rather high at the conditions of superplastic deformation for the CrWMn steel, the activation energy for superplastic deformation of steel CrWMn above the critical temperature is 187KJ/mol, and the superplastic deformation activation energy is approached to the grain boundary diffusion activation energy of γ-Fe. This indicates that the grain boundary sliding (GBS) in superplastic deformation of CrWMn steel is controlled by grain boundary diffusion. The characters of superplastic deformation of the steel above the critical temperature, on the other hand, are also analyzed in this paper.

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Materials Science Forum (Volumes 551-552)

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341-345

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July 2007

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© 2007 Trans Tech Publications Ltd. All Rights Reserved

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[1] O. D. Sherby, T. G. Nieh and J. Wadsworth: Mater. Sci. Forum Vol. 170-172(1994), p.13.

Google Scholar

[2] B. P. Kasshyap, A. Arieli and A. k. Mukher jee: J. Mater. Sci. Vol. 20(1985), p.2661.

Google Scholar

[3] Y. Komizo and Y. Maehara: Transactions of the Japan Welding Society Vol. 19(1988), p.3.

Google Scholar

[4] Jiuba Wen and Jukui Xi: Journal of Materials Science Letters Vol. 12(1993), p.584.

Google Scholar

[5] Jiuba Wen and Xi Jukui: Acta Metallurgica Sinica(in Chinese) Vol. 29(1993), p. B474.

Google Scholar

[6] C.H. Xu, J.K. Xi, and W. Gao: Journal of Materials Processing Technology (in Chinese) Vol. 65(1997) pp.94-98.

Google Scholar

[7] Jiuba Wen: Researches on superplastic thermo-mechanical-treatment of die steels[D], Luoyang, Luoyang Institute of Technology, Master Thesis, (1992).

Google Scholar

[8] K. A. Padmanabhan, G. J. Davies: Superplasticity, Springer-Verlag Berlin Heidelberg New York, (1980).

Google Scholar

[9] Jingsu He and Yanwen Wang: The Superplasticity of Metals(Science Press, China 1986).

Google Scholar

[10] C. Gandhi, R. Raj: Acta Metall. Mater. Vol. 39(1991), p.679.

Google Scholar

[11] M. Mabuchi: Acta Mater. Vol. 47(1999), p. (1915).

Google Scholar

[12] T. Sakuma: Materials Science Forum Vol. 243-245(1997), p.327.

Google Scholar

[13] J.B. Wen and Y.S. Yang: Journal of Materials Science and Technology Vol. 17 (2001), p.175.

Google Scholar