Abstract
Hot hardness was measured on the primary carbides, (Fe, Cr)3C and (Fe, Cr)7C3, in unidirectionally solidified iron-carbon-chromium hypereutectic alloys with chromium more than 4.8 wt %. The hardness-temperature relation was represented by two Ito-Shishokin formulae,H v =A(— BT), and thus was drawn by two lines on a semilogarithmic graph. The inflection temperature where the two lines intersected was found at 730 to 860 K for (Fe, Cr)3C carbide containing 0 to 14 wt % Cr, increasing with an increase in the chromium concentration in the carbide, and at about 910 K for (Fe, Cr)7C3 carbide containing 36 to 76 wt % Cr. With increasing chromium concentration in each carbide, the hardness of the carbide increased and the thermal softening coefficients decreased. The effect of chromium on the hardness, the inflection temperature and the thermal softening coefficients was more pronounced for (Fe, Cr)3C carbide than for (Fe, Cr)7C3 carbide. Each of the thermal softening coefficients,B 1(T<T t),B 2(T>T t), the inflection temperature,T t, room-temperature hardness,H v(T RT), and the hardness atT t,H v(T t), related linearly to the chromium concentration in the carbides, and hence the hot hardness of the carbides could be expressed as functions of temperature and chromium concentration in the carbides. The relationships betweenH v(T RT) andH v(T t) and between the thermal softening coefficient,B 2, and the activation energy for creep,Q c(kJ mol−1), were represented by the following equations:H v(T t)≃0.7H v(T RT),B 2=1.26/Q c.
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References
J. M. Bereza,Br. Foundrym. 174 (1981) 205.
A. Kagawa andT. Okamoto,J. Mater. Sci. 18 (1983) 225.
“ASM Metals Handbook” 8th edn Vol. 8 (American Society for Metals, Cleveland, Ohio, 1973) p. 402.
J. Dodd andJ. L. Parks,AFS Int. Cast. Met. J. 5 (3) (1980) 47.
A. Kagawa andT. Okamoto,Trans. Jpn. Inst. Met. 20 (1979) 659.
E. J. Janitzky andM. Baeyertz, “Metals Handbook” (American Society for Metals, Cleveland, Ohio, 1939) p. 515.
D. Tabor,Proc. Roy. Soc. Lond. A192 (1948) 247.
F. P. Bens,Trans. ASM 38 (1947) 505.
J. H. Westbrook andH. Conrad, “The Science of Hardness Testing and Its Research Applications” (American Society for Metals, Cleveland, Ohio, 1973) p. 60.
E. R. Petty andH. O'neill,Metallurgia 63 (1961) 25.
C. Barus,Phys. Rev. 30 (1910) 347.
S. R. Williams,Trans. Amer. Soc. Steel Treating 5 (1924) 562.
A. Kurth,Z. Verein deutsch. Ing. 53 (1909) 85.
P. Ludwik,Z. physikal. Chem. 91 (1916) 232.
F. Waizenegger,Z. Verein. deutsch. Ing. 65 (1921) 824.
K. Ito,Tohoku Sci. Rep. 12 (1923) 137.
V. P. Shishokin,Z. Anorg. Chemie 189 (1930) 263.
G. M. Schwab,Trans. Faraday Soc. 45 (1949) 385.
J. H. Westbrook,Trans. ASM 45 (1953) 221.
O. Kubaschewski andC. B. Alcock, “Metallurgical Thermochemistry” 5th edn (Pergamon Press, Oxford, 1979) p. 328.
M. G. Lozinskii, “High Temperature Metallography” (Pergamon, Oxford, 1961) p. 319.
E. R. Petty,Metallurgia 56 (1957) 231.
K. Kumagai andT. Kayaba, private communication (1976).
F. Garofalo, “Fundamentals of Creep and Creep-Rupture in Metals” (Macmillan, New York, 1965) p. 6.
A. G. Atkins andD. Tabor,J. Amer. Ceram. Soc. 50 (1967) 195.
C. J. Smithells, “Metals Reference Book” Vol. 2 (Butterworths, London, 1967) p. 645.
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Kagawa, A., Okamoto, T., Saito, K. et al. Hot hardness of (Fe, Cr)3C and (Fe, Cr)7C3 carbides. J Mater Sci 19, 2546–2554 (1984). https://doi.org/10.1007/BF00550808
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DOI: https://doi.org/10.1007/BF00550808