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

The following relation given in the previous report is also in the neighbourhood of 4 K for iron and BCC iron alloys:(This article is not displayable. Please see full text pdf.) \ oindentwhere 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.