Our research and results from the literature all consistently suggest a binding energy of nearest-neighbor carbon-vacancy (C-V) pairs of the order 35 to 40 kJ/mole in austenitic alloys. Results examined include point-defect anelasticity, self-diffusion, high-temperature creep, strain aging, strain-age hardening, radiation damage, and point-defect structure modeling. Increases in the height of carbon-based anelastic peaks by quenching, cold work, and electron irradiation are consistent with a substantial nonexclusive contribution of C-V complexes. Increased carbon content in austenite increases the iron self-diffusivity and the high-temperature creep rate of fcc Fe, implying a C-V binding energy of ϳ40 kJ/mol. Dynamic strain aging of carbon-containing austenites occurs in temperature ranges too low to involve interstitial solute mobility and requires an interpretation of large C-V binding wherein the vacancy is the more mobile component. Strengthening in heavily deformed austenitic stainless steels associated with strain aging or long-term aging near room temperature implies solution hardening by tetragonal-like C-V complexes formed at these temperatures. Results on radiation damage of austenitic steels show effects of carbon on irradiation susceptibility. Finally, we have performed first-principles gradient-corrected density functional calculations to determine the binding energy of nearest-neighbor C-V pairs in fcc iron; a value of ϳ35 kJ/mol is obtained.
A new approach to the analysis of preferred orientation in body centered cubic sheet materials is presented. The technique utilizes normalized extended inverse pole figures (2θ = 16 to 150°) taken in the plane normal, rolling, and transverse directions. Possible texture components are defined to be all unique sets of three mutually orthogonal crystallographic planes included in the diffraction pattern up to 150° 2θ for a total of 56 possible components. A computer program has been developed to calculate the contributions of various texture components relative to the three principal directions by two computer implemented algorithms, probability and successive decrementation. The two methods exhibit an apparent high correlation.The calculated results are compared to monochromated direct pole figures for a highly textured material. The agreement is excellent.
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