日本金属学会誌

J. Japan Inst. Metals, Vol. 57, No. 11 (1993),
pp. 1275-1280

Influence of N and Ni on Temperature Dependence of Fracture Toughness of Low Alloy Steel at Low Temperatures

Hisaki Okabayashi

Nuclear Power Division, Isikawajima-Harima Heavy Indus. Co. Ltd., Yokohama

Abstract:

The following relation given in the previous report is also in the neighbourhood of 4 K for iron and BCC iron alloys:
\begin{equation*}
Gic=G0\exp(T/T0),1/T0=(1/T0.1)(d/0.1)-1/7
\end{equation*}

where Gic is the critical strain-energy release rate, T the testing temperature, and d is the grain size (mm).

The results obtained in the present study indicate that (1) Gic extrapolated to 0 K, i.e. G0, depends upon solute nitrogen and carbon contents as a fuction of ([C]+4[N])at.%; (2) G0 values are 1.1 kJ/m2 when the nitrogen and carbon contents are zero or under the tempered condition, and (3) the temperature dependence of Gic, i.e. 1/T0, increases with increasing nickel content, while it decreases with increasing nitrogen content.


(Received May 31, 1993)

Keywords:

fracture toughness, iron, steel, nitrogen, nickel, liquid helium


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