Elevated temperature creep crack growth: State-of-the-art review and recommendations

Abstract Presented in this paper is a detailed literature review of the emerging technology of creep crack growth. The application of this technology is directed at components which must withstand thermo-mechanical loads in high temperature range. Examples are components of breeder reactor systems and turbine disk alloys for aerospace applications. Component failures due to creep crack growth have been reported to occur in heat-affected zones and in defective welds. However, current design codes (such as ASME) do not permit crack-like defects in creep range. The essential feature of creep is that it is a thermally activated process involving significant time-dependent plastic and creep deformations. Much effort in the past decade has been directed toward experimentally identifying the parameters that would govern crack growth under creep conditions. However, no completely successful single parameter has emerged. The review is divided into a discussion of the basic creep deformation mechanisms, experimental crack growth correlations, analytical predictions, and numerical computations. Greater emphasis is given to describing the developments in the past five years. Finally, a combined numerical and experimental program is recommended for further research in this area. An alternate strategy to select pertinent experimental data from the published literature and to use them to conduct numerical/analytical work is also suggested, which would be much more economical to pursue.