Abstract
The effect of the grain-boundary microstructures on the creep-rupture properties and the initiation and growth of the grain-boundary cracks was investigated using four kinds of specimen of various grain-boundary microstructures in the cobalt-base HS-21 alloy at 1089 K in air. Both the rupture strength and the creep ductility increased with increasing mean value of the fractal dimension of the grain boundaries, Dgb. The strain to crack initiation was largest in the specimen of the highest value (1.241), while the strain was much the same in the specimens of the Dgb value less than 1.162. This was explained by the local variation in the grain-boundary microstructures in these specimens. The mean value of the fractal dimension of the grain-boundary fracture, Df, was close to the value of Dgb, although the value of Df was a little higher than that of Dgb in the specimens of the lower Dgb values. The fracture appearance changed from a brittle grain-boundary fracture to a ductile one with increasing values of Dgb and Df. The crack-growth rate is the surface-notched specimens decreased with increasing value of Dgb. The threshold stress intensity factor for crack growth was higher in the specimens with the higher Dgb values.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
W. BETTERIDGE and A. W. FRANKLIN, J. Inst. Metals 85 (1956—57) 473.
M. YAMAZAKI, J. Jpn Inst. Metals 30 (1966) 1032.
V. LUPINC, “High Temperature Alloys for Gas Turbines 1982” (Reidel, Dordrecht, 1982) p. 395.
M. KOBAYASHI, O. MIYAGAWA, T. SAGA and D. FUJISHIRO, J. Iron Steel Inst. Jpn 58 (1972) 79.
M. YAMAMOTO, O. MIYAGAWA, M. KOBAYASHI and D. FUJISHIRO, ibid. 63 (1977) 1848.
M. TANAKA, O. MIYAGAWA, T. SAKAKI and D. FUJISHIRO, ibid. 65 (1979) 939.
M. TANAKA, O. MIYAGAWA, T. SAKAKI, H. IIZUKA, F. ASHIHARA and D. FUJISHIRO, J. Mater. Sci. 23 (1988) 621.
M. TANAKA, H. IIZUKA and F. ASHIHARA, ibid. 24 (1989) 1623.
M. F. ASHBY, R. RAJ and R. C. GIFKINS, Scripta Metall. 4 (1970) 737.
R. RAJ and M. F. ASHBY, Metall. Trans. 2 (1971) 1113.
F. W. CROSSMAN and M. F. ASHBY, Acta Metall. 23 (1975) 425.
B. B. MANDELBROT, D. E. PASSOJA and A. J. PAULLAY, Nature 308 (1984) 721.
V. Y. MILMAN, N. A. STELMASHENKO and R. BLUMENFELD, Progr. Mater. Sci. 38 (1994) 425.
B. B. MANDELBROT, “The Fractal Geometry of Nature,” translated by H. Hironaka (Nikkei Science, Tokyo, 1985) p. 25.
M. TANAKA, J. Mater. Sci. 27 (1992) 4717.
Idem, ibid. 28 (1993) 5753.
M. TANAKA and H. IIZUKA, Z. Metallkde. 82 (1991) 442.
A. M. GOKHALE, W. J. DRURY and S. MISHRA, ASTM STP 1203, edited by J. E. Masters and L. N. Gilbertson (American Society for Testing and Materials, Philadelphia, PA, 1993) p. 3.
W. J. DRURY and A. M. GOKHALE, ibid., p. 58.
H. TAKAYASU, “Fractals in the Physical Sciences,” (Manchester University Press, Manchester, New York, 1990 p. 11.
S. ISHIMURA and S. ISHIMURA, “Fractal Mathematics,” (Tokyo Tosho, Tokyo, 1990) p. 246.
M. TANAKA, H. IIZUKA and F. ASHIHARA, J. Mater. Sci. 23 (1988) 3827.
R. H. DAUSKARDT, F. HAUBENSAK and R. O. RITCHIE, Acta Metall. 38 (1990) 142.
A. KIUCHI, M. AOKI, M. KOBAYASHI and K. IKEDA, J. Iron Steel Inst. Jpn 68 (1982) 1830.
H. KITAGAWA and R. YUUKI, Trans. Jpn. Soc. Mech. Eng. 41-346 (1975) 1641.
M. ISHIDA, Trans. Jpn. Soc. Mech. Eng. 45-392 (1979) 306.
S. SURESH, Metall. Trans. 14A (1983) 2375.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
TANAKA, M. The creep-rupture properties and the initiation and growth of the grain-boundary cracks in the cobalt-base HS-21 alloy. Journal of Materials Science 32, 1781–1788 (1997). https://doi.org/10.1023/A:1018536319231
Issue Date:
DOI: https://doi.org/10.1023/A:1018536319231