Nucleation Rate and Number of Precipitates in V and Nb-Microalloyed Steels

Abstract:

Recrystallization-precipitation-time-temperature (RPTT) diagrams were experimentally determined for two microalloyed steels with V and Nb, respectively, at a strain of 0.35 and a strain rate of 3.63 s^-1. From the RPTT diagrams, and applying the classic theory of nucleation, the nucleation rate was calculated for both steels. In order to determine the mentioned magnitudes, several parameters were calculated, such as: the Zeldovich factor (Z), the energy of formation of the nucleus (ΔG), the driving force for precipitation (ΔGv), the critical radius for nucleation (Rc), and the dislocation density at the start of precipitation (ρ), among others. The calculated data has made it possible to clarify the shape of precipitation start and finish curves and to plot the nucleation rate as a function of temperature. The number of precipitates was calculated by integration of the nucleation rate expression. In this way, substantial differences were established between the two types of microalloyed steels, including the final size of the V(C, N) and Nb (C, N) precipitates.

• Periodical: Materials Science Forum (Volumes 783-786)
• Pages: 892-897
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.783-786.892
• Online since: May 2014
• Authors: Sebastián F. Medina*, Manuel Gómez
• Keywords: Microalloyed Steel, Nucleation Rate, Nucleus Size, Precipitate

References

[1] K. Xu, B.G. Thomas, R. O'Malley, Metall. Mater. Trans. A. 42 (2011) 524-539.

[2] C.M. Sellars: Mater. Sci Technol. 6 (1990) 1072-1081.

[3] E. J. Palmiere, C.I. Garcia, A.J. DeArdo, Metall. Mater. Trans. A 25 (1994) 277-286.

[4] W.J. Liu, Metall. Mater. Trans. A 26 (1995) 1641-1657.

[5] B. Dutta, E, Valdes, C.M. Sellars: Acta Metall. Mater. 40 (1992) 653-662.

[6] B. Dutta, E.J. Palmiere, C.M. Sellars, Acta Mater. 49 (2001) 785-794.

[7] K.C. Russel, Adv. Colloid. Interface Sci. 13 (1980) 205-318.

[8] R. Kampmann, R. Wagner: Mater. Sci. Tech. A Comprenhensive Treatment, ed. R.W. Cahn, P. Hassen and E.J. Krammer, VCH Verlagsgesselschaft mbH, Weinheim, 1991, vol. 5, p.213.

[9] E.T. Turkdogan: Iron Steelmaker 3 (1989) 61-75.

[10] A. Faessel: Rev. Métall,. Cah. Inf. Tech. 33 (1976) 875-892.

[11] S.F. Medina and C.A. Hernández: Acta Mater. 44 (1996) 155-163.

[12] M. Gómez, S. F. Medina, A. Quispe, P. Valles: ISIJ Int. 42 (2002) 423-431.

[13] S.F. Medina, A. Quispe, M. Gómez: Mater. Sci. Technol. 19 (2003) 99-108.

[14] M. Perez, M. Dumont, D. Acevedo-Reyes: Acta Mater. 56 (2008) 2119-2132.

[15] N. Fujita, H.K.D.H. Bhadeshia: Mater. Sci. Tecnol. 17 (2001) 403-408.

[16] P. Maugis, M. Gouné: Acta Mater. 53 (2005) 3359-3367.

[17] W.P. Sun, M. Militzer, D.Q. Bai, J.J. Jonas: Acta metal. Mater. 41 (1993) 3595-3604.

[18] B. Dutta, E. Valdes, C.M. Sellars: Acta Metall. Mater. 40(1992) 653-662.

[19] F. Perrard, A. Deschamps, P. Maugis: Acta Mater. 55 (2007) 1255-1266.

[20] E.T. Turkdogan: Iron Steelmaker 16.

[1989] 61-75.

[21] M. Perez, D. Acevedo-Reyes, T. Courtois, E. Epicier, P. Maugis: Phil. Mag. Lett. 87 (2007) 645-656.

[22] S.F. Medina, L. Rancel, M. Gómez, R. Ishak, M. de Sanctis: ISIJ Int. 48 (2008) 1603-1608.

DOI: 10.2355/isijinternational.48.1603

[23] T. Gladman: The physical metallurgy of microalloyed steels, The Institute of Materials, London, (1997).

[24] S. Vervynckt, K. Verbeken, P. Thibaux, Y. Houbaert: Mater. Sci. Eng. A. 528 (2011) 5519-5528.

[25] H. Oikawa: Tetsu-to-hagane 68 (1982) 1489-1497.