Evaluation of Grain Boundary Effect on the Strength of Fe-C Martensitic Steels through Nanoindentation Technique

Abstract:

Nanoindentation measurements were performed for Fe-C based martensitic steels, and then the strengthening factors such as grain boundary effect were evaluated. Nanohardness of the matrix of the martensite is lower than that expected from macroscopic hardness, indicating that the grain boundary effect is significant for the macroscopic strength of the Fe-C martensite. A remarkable decrease of the grain boundary effect was found at the tempering temperature of 673 K, which is due to a disappearance of film-like carbides on grain boundaries. These results will be discussed in light of the interpretations of grain boundary strengthening.

• Periodical: Materials Science Forum (Volumes 475-479)
• Pages: 4113-4116
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.475-479.4113
• Online since: January 2005
• Authors: Takahito Ohmura, Kaneaki Tsuzaki
• Keywords: Fe-C Martensite, Grain Boundary Effect, Hardness, Mechanical Property, Nanoindentation

References

[1] A.R. Marder and G. Krauss: Trans. ASM Vol. 60 (1967), p.651.

[2] J.M. Marder and A.R. Marder: Trans. ASM Vol. 62 (1969), p.1.

[3] A.R. Marder and G. Krauss, Trans. ASM Vol. 62 (1969), p.957.

[4] T. Maki K. Tsuzaki and I. Tamura: Trans ISIJ Vol. 20 (1980), p.207.

[5] W.C. Leslie and R.J. Sober: Trans. ASM Vol. 60 (1967), p.459.

[6] L. -A. Norstrom: Scand. J. Metall. Vol. 5 (1976), p.159.

[7] F.B. Pickering: Hardenability Concepts with Applications to Steel (AIME, USA, 1978).

[8] G. Krauss: Hardenability Concepts with Applications to Steel (AIME, USA, 1978).

[9] G. Krauss: Mater. Sci. Eng. Vol. A273-275 (1999), p.40.

[10] P.M. Kelly and M. Kehoe: Suppl. Trans. JIM Vol. 17 (1976), p.399.

[11] T. Furuhara, S. Morito and T. Maki: J. Phys. IV Vol. 112 (2003), p.255.

[12] T. Ohmura, K. Tsuzaki and S. Matsuoka: Scripta Mater. Vol. 45 (2001), p.889.

[13] T. Ohmura, K. Tsuzaki and S. Matsuoka: Phil. Mag. A Vol. 82 (2002), p. (1903).

[14] T. Ohmura, T. Hara and K. Tsuzaki: J. Mater. Res. Vol. 18 (2003), p.1465.

[15] T. Ohmura, T. Hara and K. Tsuzaki: Scripta Mater. Vol. 49 (2003), p.1157.

[16] W.C. Oliver and G.M. Pharr: J. Mater. Res. Vol. 7 (1992), p.1564.

[17] J. D. Eshelby, F.C. Frank and F.R.N. Nabaro: Phil. Mag. Vol. 42 (1951), 351.

[18] A.N. Stroh: Proc. Roy. Soc. Vol. 223 (1954), 404. Fig. 4 Schematic representation of a Hall-Petch plot for the tempered martensitic steels d -1/2 σ (Hn~σ0 )573K (Hn~σ0 )723K (Hv~σf )573K (Hv~σf )723K k723K k573K 0 0.